{"id":1410,"date":"2019-02-18T13:30:16","date_gmt":"2019-02-18T04:30:16","guid":{"rendered":"https:\/\/www.bold.ne.jp\/engineer-club\/?p=1410"},"modified":"2025-10-06T17:09:35","modified_gmt":"2025-10-06T08:09:35","slug":"java-map","status":"publish","type":"post","link":"https:\/\/www.bold.ne.jp\/engineer-club\/java-map","title":{"rendered":"Java\u306eMap\u3068\u306f\uff1f\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u3066\u4fdd\u5b58\u3059\u308b\u305f\u3081\u306eMap\u306e\u4f7f\u3044\u65b9"},"content":{"rendered":"<p><strong>Map\u306f\u3001Java\u3067\u30ad\u30fc\u3068\u5024\u3092\u30bb\u30c3\u30c8\u306b\u3057\u3066\u6271\u3044\u305f\u3044\u6642\u306b\u4f7f\u3046\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u3059\u3002<\/strong><br \/>\n\u4ed6\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u3067\u3001\u30cf\u30c3\u30b7\u30e5\u30c6\u30fc\u30d6\u30eb\u30fb\u30c7\u30a3\u30af\u30b7\u30e7\u30ca\u30ea\u30fb\u9023\u60f3\u914d\u5217\u306a\u3069\u3068\u547c\u3070\u308c\u308b\u3082\u306e\u306b\u8fd1\u3044\u4f7f\u3044\u65b9\u304c\u3067\u304d\u308b\u3082\u306e\u3067\u3059\u3002<\/p>\n<p>Map\u306e\u6a5f\u80fd\u306f\u30b7\u30f3\u30d7\u30eb\u3067\u3059\u304c\u3001\u5fdc\u7528\u7bc4\u56f2\u306f\u3068\u3066\u3082\u5e83\u304f\u3001<span>Java<\/span>\u3067\u5b9f\u7528\u7684\u306a\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u308b\u6642\u306f\u5927\u4f53\u304a\u4e16\u8a71\u306b\u306a\u308b\u3082\u306e\u3067\u3059\u3002<br \/>\n\u3060\u304b\u3089\u3053\u305d\u3001<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u3092\u3088\u304f\u77e5\u3063\u3066\u3044\u308c\u3070\u3001\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3092\u3068\u3066\u3082\u697d\u306b\u3001\u52b9\u7387\u7684\u306b\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u9006\u306b\u8a00\u3048\u3070\u3001<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u3092\u8aa4\u308c\u3070\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u3068\u3066\u3082\u8aad\u307f\u306b\u304f\u3044\u3001\u4f7f\u3044\u306b\u304f\u3044\u3082\u306e\u306b\u306a\u3063\u3066\u3057\u307e\u3044\u304b\u306d\u307e\u305b\u3093\u3002<br \/>\n\u3067\u3082\u3001\u3044\u304f\u3064\u304b\u306e\u57fa\u790e\u7684\u306a\u77e5\u8b58\u3084\u30dd\u30a4\u30f3\u30c8\u3092\u62bc\u3055\u3048\u308b\u3060\u3051\u3067\u3001<span>Map<\/span>\u306e\u529b\u3092\u751f\u304b\u3057\u305f\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306f\u5341\u5206\u306b\u884c\u3048\u308b\u306e\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001<span>Map<\/span>\u306e\u7279\u5fb4\u3092\u7406\u89e3\u3059\u308b\u3068\u3053\u308d\u304b\u3089\u59cb\u3081\u3066\u3001<span>Map<\/span>\u306e\u57fa\u672c\u7684\u306a\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u3068\u5b9f\u7528\u7684\u306a\u6d3b\u7528\u306e\u4ed5\u65b9\u3001\u77e5\u3063\u3066\u304a\u3051\u3070\u3061\u3087\u3063\u3068\u5f97\u3059\u308b\u30ef\u30f3\u30dd\u30a4\u30f3\u30c8\u7684\u306a\u3053\u3068\u307e\u3067\u3001\u5e45\u5e83\u304f\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002<\/p>\n<p>\u203b\u3053\u306e\u8a18\u4e8b\u306e\u30b5\u30f3\u30d7\u30eb\u306f\u3001<span>Java 11<\/span>\u306e\u74b0\u5883\u3067\u52d5\u4f5c\u78ba\u8a8d\u3057\u3066\u3044\u307e\u3059<\/p>\n<div id=\"toc_container\" class=\"no_bullets\"><p class=\"toc_title\">\u76ee\u6b21<\/p><ul class=\"toc_list\"><li><a href=\"#JavaMap\">\uff11\uff0e\u3010Java\u3011Map\u3068\u306f\u3069\u3093\u306a\u3082\u306e\u304b<\/a><ul><li><a href=\"#-Map\">\uff11-\uff11\uff0eMap\u306f\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u3066\u4fdd\u5b58\u3059\u308b\u30e2\u30ce<\/a><\/li><li><a href=\"#-Map-2\">\uff11-\uff12\uff0eMap\u306f\u3067\u304d\u308b\u3053\u3068\u304c\u6c7a\u307e\u3063\u3066\u3044\u308b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9<\/a><\/li><li><a href=\"#-Map-3\">\uff11-\uff13\uff0eMap\u304c\u3067\u304d\u308b\u3053\u3068\u3001\u4ed6\u306e\u30c7\u30fc\u30bf\u69cb\u9020\u3068\u306e\u9055\u3044<\/a><\/li><\/ul><\/li><li><a href=\"#MapJava_7\">\uff12\uff0e\u3010\u57fa\u672c\u3011Map\u306e\u4f7f\u3044\u65b9(\uff5eJava 7)<\/a><ul><li><a href=\"#-Map-4\">\uff12-\uff11\uff0e\u3010\u91cd\u8981\u3011Map\u3067\u306f\u578b\u5f15\u6570\u3067\u30ad\u30fc\u3068\u5024\u3092\u6307\u5b9a\u3057\u3088\u3046!!<\/a><\/li><li><a href=\"#-put\">\uff12-\uff12\uff0eput\u3067\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u308b<\/a><\/li><li><a href=\"#-get\">\uff12-\uff13\uff0eget\u3067\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u5024\u3092\u53d6\u308a\u51fa\u3059<\/a><\/li><li><a href=\"#-remove\">\uff12-\uff14\uff0eremove\u3067\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b<\/a><\/li><li><a href=\"#-clear\">\uff12-\uff15\uff0eclear\u3067\u3059\u3079\u3066\u306e\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b<\/a><\/li><li><a href=\"#i\">\uff12-\uff16\uff0e\u30ad\u30fc\u3084\u5024\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<\/a><\/li><li><a href=\"#-SetCollection\">\uff12-\uff17\uff0e\u30ad\u30fc\u3084\u5024\u3092Set\u3084Collection\u3067\u53d6\u308a\u51fa\u3059<\/a><\/li><\/ul><\/li><li><a href=\"#Map\">\uff13\uff0e\u3010\u5fdc\u7528\u3011Map\u306e\u6d3b\u7528\u65b9\u6cd5\u3044\u308d\u3044\u308d<\/a><ul><li><a href=\"#i-2\">\uff13-\uff11\uff0e\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u30fb\u5206\u985e\u30fb\u52a0\u5de5\u306b\u4f7f\u3046<\/a><\/li><li><a href=\"#i-3\">\uff13-\uff12\uff0e\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u7c21\u6613\u7684\u306a\u8868\u73fe\u306b\u4f7f\u3046<\/a><\/li><li><a href=\"#i-4\">\uff13-\uff13\uff0e\u30c7\u30fc\u30bf\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u4f7f\u3046<\/a><\/li><li><a href=\"#-Map-5\">\uff13-\uff14\uff0e\u3010\u53c2\u8003\u3011Map\u3092\u30d5\u30a1\u30a4\u30eb\u3078\u8aad\u307f\u66f8\u304d\u3059\u308b<\/a><\/li><\/ul><\/li><li><a href=\"#Map-2\">\uff14\uff0e\u3010\u91cd\u8981\u3011Map\u3092\u4f7f\u3046\u306e\u306b\u6b20\u304b\u305b\u306a\u3044\u3082\u306e<\/a><ul><li><a href=\"#-Objectequals\">\uff14-\uff11\uff0e\u3010\u5fc5\u9808\u3011Object.equals\u306f\u30ad\u30fc\u304c\u540c\u3058\u304b\u306e\u5224\u65ad\u306b\u4f7f\u3046<\/a><\/li><li><a href=\"#-ObjecthashCodeMap\">\uff14-\uff12\uff0eObject.hashCode\u306f\u4e00\u90e8\u306eMap\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3067\u306f\u5fc5\u9808<\/a><\/li><li><a href=\"#-Comparable\">\uff14-\uff13\uff0eComparable\u306f\u305c\u3072\u610f\u8b58\u3057\u305f\u3044\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9<\/a><\/li><\/ul><\/li><li><a href=\"#MapJava_8\">\uff15\uff0e\u3010\u767a\u5c55\u3011Map\u306bJava 8\u4ee5\u964d\u3067\u8ffd\u52a0\u3055\u308c\u305f\u6a5f\u80fd<\/a><ul><li><a href=\"#-putIfAbsentJava_8\">\uff15-\uff11\uff0eputIfAbsent\u3067\u3001\u5bfe\u5fdc\u4ed8\u3051\u304c\u306a\u3044\u6642\u306e\u5024\u3092\u6307\u5b9a\u3059\u308b\u3010Java 8\uff5e\u3011<\/a><\/li><li><a href=\"#-replaceJava_8\">\uff15-\uff12\uff0ereplace\u3067\u30ad\u30fc\u304c\u3042\u308b\u306a\u3089\u5024\u3092\u5165\u308c\u66ff\u3048\u308b\u3010Java 8\uff5e\u3011<\/a><\/li><li><a href=\"#-computemergeJava_8\">\uff15-\uff13\uff0ecompute\/merge\u3067\u5024\u306e\u52a0\u5de5\u3092\u3059\u308b\u3010Java 8\uff5e\u3011<\/a><\/li><li><a href=\"#-ofcopyOfMap\">\uff15-\uff14\uff0eof\/copyOf\u3067\u5909\u66f4\u3067\u304d\u306a\u3044Map\u3092\u7c21\u5358\u306b\u4f5c\u308b<\/a><\/li><\/ul><\/li><li><a href=\"#Map-3\">\uff16\uff0e\u3010\u767a\u5c55\u3011Map\u306b\u307e\u3064\u308f\u308b\u3042\u308c\u3053\u308c<\/a><ul><li><a href=\"#-MapJavaAPI\">\uff16-\uff11\uff0eMap\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u7279\u5fb4(Java\u6a19\u6e96API)<\/a><\/li><li><a href=\"#-Map-6\">\uff16-\uff12\uff0eMap\u306e\u30ad\u30fc\u3068\u5024\u3092\u578b\u5f15\u6570\u3067\u7d5e\u308a\u8fbc\u3093\u3067\u3001\u5206\u304b\u308a\u3084\u3059\u304f\u3059\u308b<\/a><\/li><li><a href=\"#-Map-7\">\uff16-\uff13\uff0eMap\u304c\u5b58\u5728\u3059\u308b\u9650\u308a\u3001\u30ad\u30fc\u3068\u5024\u306f\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3055\u308c\u306a\u3044<\/a><\/li><li><a href=\"#-keySetvaluesentrySetMap\">\uff16-\uff14\uff0ekeySet\/values\/entrySet\u306f\u5143\u306eMap\u3068\u9023\u52d5\u3059\u308b<\/a><\/li><li><a href=\"#-Map-8\">\uff16-\uff15\uff0e\u5909\u66f4\u3067\u304d\u308bMap\u306f\u30af\u30e9\u30b9\u306e\u5916\u90e8\u306b\u516c\u958b\u3057\u306a\u3044<\/a><\/li><li><a href=\"#-IFMap\">\uff16-\uff16\uff0e\u30af\u30e9\u30b9\u5916\u90e8\u3068\u306eIF\u3067\u306f\u3001\u7d20\u306eMap\u3092\u306a\u308b\u3079\u304f\u4f7f\u308f\u306a\u3044<\/a><\/li><li><a href=\"#-Map-9\">\uff16-\uff17\uff0e\u5909\u6570\u306e\u578b\u3092Map\u3068\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u3069\u3061\u3089\u3067\u5ba3\u8a00\u3059\u3079\u304d\u304b<\/a><\/li><\/ul><\/li><li><a href=\"#i-5\">\uff17\uff0e\u307e\u3068\u3081<\/a><\/li><\/ul><\/div>\n<h2><span id=\"JavaMap\">\uff11\uff0e\u3010Java\u3011Map\u3068\u306f\u3069\u3093\u306a\u3082\u306e\u304b<\/span><\/h2>\n<h3><span id=\"-Map\">\uff11-\uff11\uff0eMap\u306f\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u3066\u4fdd\u5b58\u3059\u308b\u30e2\u30ce<\/span><\/h3>\n<p>\u30de\u30c3\u30d7<span>(map)<\/span>\u3068\u3044\u3046\u8a00\u8449\u3067\u6700\u521d\u306b\u9023\u60f3\u3059\u308b\u306e\u306f\u3001\u666e\u901a\u306f\u300c\u5730\u56f3\u300d\u3067\u3057\u3087\u3046\u304b\u3002\u3067\u3082\u3001\u30de\u30c3\u30d4\u30f3\u30b0\u3059\u308b\u3068\u3044\u3046\u8a00\u3044\u56de\u3057\u3082\u3057\u307e\u3059\u3088\u306d\u3002\u3053\u3061\u3089\u306f\u300c\u5bfe\u5fdc\u4ed8\u3051\u308b\u300d\u3068\u3044\u3046\u610f\u5473\u3067\u3059\u3002<\/p>\n<p>Java\u306e<span>java.util.Map<\/span>\u306f\u3001\u305d\u306e\u300c\u5bfe\u5fdc\u4ed8\u3051\u308b\u300d\u65b9\u306e<span>map<\/span>\u3092<span>Java<\/span>\u3067\u5b9f\u73fe\u3057\u305f\u3082\u306e\u3067\u3059\u3002\u3064\u307e\u308a\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u4e0a\u3067\u300c\u4f55\u304b\u3092\u4f55\u304b\u306b\u5bfe\u5fdc\u4ed8\u3051\u300d\u3066\u3001\u305d\u308c\u3092\u4e00\u3064\u306e<span>Map<\/span>\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3067\u3072\u3068\u307e\u3068\u3081\u306b\u3057\u3066\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u4e2d\u3067\u81ea\u7531\u306b\u6301\u3061\u904b\u3073\u304c\u3067\u304d\u308b\u306e\u3067\u3059\u3002<\/p>\n<p>Map\u306e\u767b\u5834\u4eba\u7269\u306f\u3001<span>Map<\/span>\u305d\u306e\u3082\u306e\u306e\u4ed6\u306b\u3001\u300c\u30ad\u30fc\u300d\u3068\u306a\u308b\u4f55\u304b\u306e\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3068\u3001\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u308b\u300c\u5024\u300d\u306e\u4e8c\u3064\u3067\u3059\u3002<span>Map<\/span>\u306f\u30ad\u30fc\u3068\u5024\u3092\u30bb\u30c3\u30c8\u306b\u3057\u3066\u899a\u3048\u308b\u306e\u3067\u3001\u540c\u3058\u30ad\u30fc\u306a\u3089\u5e38\u306b\u540c\u3058\u5024\u304c\u5f97\u3089\u308c\u307e\u3059\u3002\u305d\u3057\u3066\u3001\u4e00\u3064\u306e<span>Map<\/span>\u306b\u306f\u305f\u304f\u3055\u3093\u306e\u30ad\u30fc\u3092\u4e00\u5ea6\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u308b\u306e\u3067\u3059\u3002<\/p>\n<h3><span id=\"-Map-2\">\uff11-\uff12\uff0eMap\u306f\u3067\u304d\u308b\u3053\u3068\u304c\u6c7a\u307e\u3063\u3066\u3044\u308b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9<\/span><\/h3>\n<p>java.util.Map\u306f\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3067\u3059\u3002\u3064\u307e\u308a\u3001<span>Map<\/span>\u3068\u3044\u3046\u30e2\u30ce\u304c\u3067\u304d\u308b\u632f\u308b\u821e\u3044<span>(=<\/span>\u30e1\u30bd\u30c3\u30c9<span>)<\/span>\u3092\u6c7a\u3081\u305f\u3082\u306e\u3067\u3059\u3002\u305d\u3057\u3066\u3001<span>Map<\/span>\u306e\u5b9f\u4f53\u3068\u306a\u308b\u3001<span>Map<\/span>\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3092\u5b9f\u88c5\u3057\u305f\u30af\u30e9\u30b9\u304c\u7528\u9014\u5225\u306b\u4f5c\u3089\u308c\u3066\u3044\u308b\u306e\u3067\u3001\u3057\u3063\u304b\u308a\u3068\u4f7f\u3044\u5206\u3051\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044<span>\u2026<\/span>\u3068\u3044\u3046\u3053\u3068\u3067\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>Map\u304c\u3067\u304d\u308b\u4ee3\u8868\u7684\u306a\u632f\u308b\u821e\u3044\u306f\u4ee5\u4e0b\u306e\u3082\u306e\u3067\u3059\u3002<\/p>\n<ul>\n<li>\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u3066\u4fdd\u5b58\u3059\u308b<span>(put)<\/span><\/li>\n<li>\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u305f\u5024\u3092\u53d6\u5f97\u3059\u308b<span>(get)<\/span><\/li>\n<li>\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b<span>(remove)<\/span><\/li>\n<li>\u30ad\u30fc\u3092\u3059\u3079\u3066\u524a\u9664\u3059\u308b<span>(clear)<\/span><\/li>\n<li>\u30ad\u30fc\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<span>(containsKey)<\/span><\/li>\n<li>\u5024\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<span>(containsValue)<\/span><\/li>\n<li>\u30ad\u30fc\u3092\u5168\u90e8\u53d6\u5f97\u3059\u308b<span>(keySet)<\/span><\/li>\n<li>\u5024\u3092\u5168\u90e8\u53d6\u5f97\u3059\u308b<span>(values)<\/span><\/li>\n<li>\u5bfe\u5fdc\u4ed8\u3051\u305f\u30ad\u30fc\u3068\u5024\u3092\u5168\u90e8\u53d6\u5f97\u3059\u308b<span>(entrySet)<\/span><\/li>\n<\/ul>\n<h3><span id=\"-Map-3\">\uff11-\uff13\uff0eMap\u304c\u3067\u304d\u308b\u3053\u3068\u3001\u4ed6\u306e\u30c7\u30fc\u30bf\u69cb\u9020\u3068\u306e\u9055\u3044<\/span><\/h3>\n<p>Java\u3067\u306f\u3001<span>Map<\/span>\u306e\u4ed6\u306b\u3082\u3044\u308d\u3044\u308d\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u304c\u4f7f\u3048\u307e\u3059\u3002\u305d\u308c\u3089\u3068<span>Map<\/span>\u306e\u9055\u3044\u306f\u4ee5\u4e0b\u306e\u3068\u304a\u308a\u3067\u3059\u3002<span>Map<\/span>\u306e\u7279\u5fb4\u306f\u3001\u30ad\u30fc\u3092\u4f7f\u3063\u305f\u30c7\u30fc\u30bf\u306e\u9593\u63a5\u7684\u30fb\u69cb\u9020\u7684\u306a\u7ba1\u7406\u304c\u3067\u304d\u308b\u3053\u3068\u306a\u306e\u3067\u3001\u305d\u306e\u7279\u5fb4\u3092\u6d3b\u304b\u3057\u3066\u4f7f\u3044\u305f\u3044\u3067\u3059\u306d\u3002<\/p>\n<table border=\"1\" style=\"width: 100%; border-collapse: collapse; background-color: #000000;\">\n<tbody>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">\u30c7\u30fc\u30bf\u69cb\u9020<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u3067\u304d\u308b\u3053\u3068<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u5f97\u610f<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u82e6\u624b<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">Map<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u305f\u4fdd\u6301\u3001\u30ad\u30fc\u3092\u4e2d\u5fc3\u306b\u3057\u305f\u64cd\u4f5c<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u7279\u5b9a\u306e\u30ad\u30fc\u306e\u6709\u7121\u3092\u9ad8\u901f\u306b\u8abf\u3079\u308b\u3001\u30ad\u30fc\u306b\u5bfe\u3059\u308b\u5024\u3078\u306e\u9ad8\u901f\u306a\u30a2\u30af\u30bb\u30b9<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u5024\u3092\u4e2d\u5fc3\u3068\u3057\u305f\u64cd\u4f5c\u3001\u7279\u5b9a\u306e\u5024\u306e\u6709\u7121\u3092\u9ad8\u901f\u306b\u8abf\u3079\u308b<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">List<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u78ba\u4fdd\u9818\u57df\u306e\u30b5\u30a4\u30ba\u3092\u610f\u8b58\u305b\u305a\u306b\u5024\u3092\u6e9c\u3081\u308b\u3001\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u4e2d\u5fc3\u3068\u3057\u305f\u64cd\u4f5c<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30c7\u30fc\u30bf\u306e\u5358\u7d14\u8ffd\u52a0\u3001\u6e9c\u3081\u305f\u9806\u756a\u3069\u304a\u308a\u306e\u5024\u306e\u53d6\u51fa\u3057\u3001\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u4f7f\u3063\u305f\u9ad8\u901f\u306a\u30e9\u30f3\u30c0\u30e0\u30a2\u30af\u30bb\u30b9<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u7279\u5b9a\u306e\u5024\u306e\u6709\u7121\u3084\u5b58\u5728\u5148\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u9ad8\u901f\u306b\u8abf\u3079\u308b\u3001\u5024\u3092\u9014\u4e2d\u3078\u633f\u5165\u3059\u308b<span>(<\/span>\u5f97\u610f\u306a\u5b9f\u88c5\u30af\u30e9\u30b9\u3082\u3042\u308b<span>)<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">Set<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u5024\u3092\u91cd\u8907\u3055\u305b\u305a\u306b\u6e9c\u3081\u308b\u3001\u5024\u3092\u4e2d\u5fc3\u306b\u3057\u305f\u64cd\u4f5c<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u7279\u5b9a\u306e\u5024\u306e\u6709\u7121\u3092\u9ad8\u901f\u306b\u8abf\u3079\u308b\u3001\u5024\u306e\u91cd\u8907\u30c1\u30a7\u30c3\u30af<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u4f7f\u3063\u305f\u64cd\u4f5c<span>(<\/span>\u3067\u304d\u306a\u3044<span>)<\/span>\u3001\u6e9c\u3081\u308b\u9806\u756a\u3069\u304a\u308a\u306e\u51e6\u7406<span>(<\/span>\u5f97\u610f\u306a\u5b9f\u88c5\u30af\u30e9\u30b9\u3082\u3042\u308b<span>)<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">Queue<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u30eb\u30fc\u30eb\u306b\u5f93\u3063\u305f\u5024\u306e\u51fa\u3057\u5165\u308c\u3092\u30ed\u30b8\u30c3\u30af\u3092\u610f\u8b58\u305b\u305a\u306b\u3067\u304d\u308b<span>(<\/span>\u5148\u5165\u308c\u5148\u51fa\u3057\u3001\u5f8c\u5165\u308c\u5148\u51fa\u3057\u306a\u3069<span>)<\/span><\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30eb\u30fc\u30eb\u306b\u5f93\u3063\u305f\u5024\u306e\u51fa\u3057\u5165\u308c<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u4f7f\u3063\u305f\u64cd\u4f5c<span>(<\/span>\u3067\u304d\u306a\u3044<span>)<\/span>\u3001\u5024\u3092\u9014\u4e2d\u3078\u633f\u5165\u3059\u308b<span>(<\/span>\u3067\u304d\u306a\u3044<span>)<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">\u914d\u5217<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u4e8b\u524d\u306b\u78ba\u4fdd\u3057\u305f\u56fa\u5b9a\u9577\u9818\u57df\u3078\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306b\u3088\u308b\u30a2\u30af\u30bb\u30b9<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u4f7f\u3063\u305f\u9ad8\u901f\u306a\u30e9\u30f3\u30c0\u30e0\u30a2\u30af\u30bb\u30b9\u3001\u591a\u6b21\u5143\u69cb\u9020\u306e\u5bb9\u6613\u306a\u8868\u73fe<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u53ef\u5909\u9577\u9818\u57df\u3092\u6271\u3046\u3001\u5024\u3092\u9014\u4e2d\u306b\u633f\u5165\u3059\u308b<span>(<\/span>\u79fb\u3057\u66ff\u3048\u304c\u5fc5\u8981<span>)<\/span>\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u6700\u9069\u5316<span>(<\/span>\u6271\u3046\u578b\u3084\u30b5\u30a4\u30ba\u3001\u72b6\u6cc1\u306b\u3082\u3088\u308b<span>)<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 15.2204%; border-color: #000000;\">\u30af\u30e9\u30b9\uff08\u81ea\u4f5c\uff09<\/td>\n<td style=\"width: 34.7796%; border-color: #000000;\">\u30af\u30e9\u30b9\u3092\u4f5c\u3063\u305f\u30d7\u30ed\u30b0\u30e9\u30de\u306e\u610f\u56f3\u3069\u304a\u308a\u306b\u4f55\u3067\u3082\u3067\u304d\u308b<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u30e1\u30bd\u30c3\u30c9\u306b\u3088\u308b\u64cd\u4f5c\u3078\u306e\u610f\u5473\u4ed8\u3051\u3001\u51e6\u7406\u5185\u5bb9\u306e\u6700\u9069\u5316\u3001\u8981\u4ef6\u306b\u5fdc\u3058\u305f\u5024\u306e\u81ea\u7531\u306a\u4fdd\u6301\u30fb\u52a0\u5de5<\/td>\n<td style=\"width: 25%; border-color: #000000;\">\u4f5c\u308b\u4e0a\u3067\u306e\u304a\u624b\u8efd\u3055\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u6700\u9069\u5316\u3001\u5404\u7a2e\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0<span>(<\/span>\u30d7\u30ed\u30b0\u30e9\u30de\u304c\u5168\u3066\u81ea\u5206\u3067\u884c\u3046<span>)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><span id=\"MapJava_7\">\uff12\uff0e\u3010\u57fa\u672c\u3011<span>Map<\/span>\u306e\u4f7f\u3044\u65b9<span>(<\/span>\uff5e<span>Java 7)<\/span><\/span><\/h2>\n<p>\u3053\u306e\u7ae0\u3067\u306f<span>Map<\/span>\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3068\u3057\u3066<span>HashMap<\/span>\u3092\u4f7f\u3044\u307e\u3059\u304c\u3001\u4ed6\u306e<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3067\u3082\u4f7f\u3044\u65b9\u306f\u539f\u5247\u540c\u3058\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u7ae0\u3067\u7d39\u4ecb\u3059\u308b<span>Map<\/span>\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001<span>Java 7<\/span>\u307e\u3067\u306e<span>Map<\/span>\u3067\u540c\u3058\u3088\u3046\u306b\u4f7f\u3048\u307e\u3059\u3002<span>Java<\/span>\u306f<span>Java 8<\/span>\u3067\u5927\u304d\u304f\u6a5f\u80fd\u304c\u5f37\u5316\u3055\u308c\u3001<span>Map<\/span>\u3082\u4f8b\u5916\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3067\u3082\u3001\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u73fe\u5834\u3067\u306f\u307e\u3060<span>Java 7<\/span>\u4ee5\u524d\u3092\u4f7f\u3046\u3053\u3068\u3082\u3042\u308a\u307e\u3059\u3057\u3001<span>Java 7<\/span>\u307e\u3067\u306e<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u306f\u57fa\u790e\u3067\u3082\u3042\u308a\u307e\u3059\u306e\u3067\u3001\u305c\u3072\u30de\u30b9\u30bf\u30fc\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>Java 8\u4ee5\u964d\u3067<span>Map<\/span>\u306b\u8ffd\u52a0\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u306f\u5225\u306e\u7ae0\u306b\u8a18\u8f09\u3057\u307e\u3057\u305f\u306e\u3067\u3001\u305c\u3072\u304a\u8aad\u307f\u304f\u3060\u3055\u3044\u3002\u8272\u3005\u306a\u3053\u3068\u304c\u7c21\u5358\u306b\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3088\u3002<\/p>\n<h3><span id=\"-Map-4\">\uff12-\uff11\uff0e\u3010\u91cd\u8981\u3011<span>Map<\/span>\u3067\u306f\u578b\u5f15\u6570\u3067\u30ad\u30fc\u3068\u5024\u3092\u6307\u5b9a\u3057\u3088\u3046<span>!!<\/span><\/span><\/h3>\n<p>\u3053\u306e\u8a18\u4e8b\u306e\u4f8b\u3067\u306f\u3001<span>Map<\/span>\u3078\u306e\u578b\u5f15\u6570\u3092\u4f7f\u3044\u307e\u3059\u3002\u578b\u5f15\u6570\u306b\u3064\u3044\u3066\u3054\u5b58\u3058\u3067\u306a\u3044\u65b9\u5411\u3051\u306b\u3001\u7c21\u5358\u306b\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n<p>\u578b\u5f15\u6570\u3068\u306f\u3001<span>Map<\/span>\u306e<span>API<\/span>\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8<span>(Javadoc)<\/span>\u3067<span>K<\/span>\u3084<span>V<\/span>\u3068\u66f8\u304b\u308c\u3066\u3044\u308b\u3082\u306e\u3067\u3059\u3002<span>K<\/span>\u304c\u30ad\u30fc\u3068\u306a\u308b\u30af\u30e9\u30b9<span>(Key<\/span>\u306e<span>K)<\/span>\u3001<span>V<\/span>\u304c\u5024\u3068\u306a\u308b\u30af\u30e9\u30b9<span>(Value<\/span>\u306e<span>V)<\/span>\u306e\u3053\u3068\u3067\u3059\u3002\u4f55\u3082\u6307\u5b9a\u3057\u306a\u3044\u3068\u3001<span>K<\/span>\u3082<span>V<\/span>\u3082\u3069\u3093\u306a\u30af\u30e9\u30b9\u3067\u3082\u3042\u3066\u306f\u307e\u308b<span>Object<\/span>\u306b\u306a\u308a\u307e\u3059\u304c\u3001\u3053\u308c\u3092\u30d7\u30ed\u30b0\u30e9\u30de\u304c\u81ea\u7531\u306b\u6307\u5b9a\u3067\u304d\u308b\u306e\u3067\u3059\u3002<\/p>\n<h4>\uff12-\uff11-\uff11\uff0eMap\u3067\u306e\u578b\u5f15\u6570\u306e\u4f7f\u3044\u65b9<\/h4>\n<p>Map\u306e\u5909\u6570\u5ba3\u8a00\u306e<span>&lt;&gt;<\/span>\u3067\u304f\u304f\u3089\u308c\u305f\u90e8\u5206\u3092\u4f7f\u3063\u3066\u3001\u305d\u306e<span>Map<\/span>\u306e<span>K<\/span>\u3084<span>V<\/span>\u304c\u5b9f\u969b\u306b\u4f55\u304b\u3092\u6307\u5b9a\u3057\u307e\u3059\u3002\u578b\u5f15\u6570\u3092\u4f7f\u3063\u3066<span>Map<\/span>\u306e\u5909\u6570\u3092\u5ba3\u8a00\u3059\u308b\u3068\u3001\u30ad\u30fc\u3068\u5024\u306b\u306f\u6307\u5b9a\u3057\u305f\u30af\u30e9\u30b9\u3057\u304b\u4f7f\u3048\u306a\u3044\u3088\u3046\u306b\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u30c1\u30a7\u30c3\u30af\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u300cMap&lt;String, Integer&gt;\u300d\u306a\u3089\u3001\u6700\u521d\u306eString\u306f\u30ad\u30fc\u306e\u30af\u30e9\u30b9\u3067\u3001\u6b21\u306eInteger\u306f\u5024\u306e\u30af\u30e9\u30b9\u3067\u3059\u3002\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3001\u8272\u3005\u306a\u30d1\u30bf\u30fc\u30f3\u3067\u6307\u5b9a\u304c\u3067\u304d\u307e\u3059\u3002\u305d\u308c\u306b\u5c11\u3005\u3084\u3084\u3053\u3057\u3044\u3067\u3059\u304c\u3001\u578b\u5f15\u6570\u306e\u4e2d\u306b\u578b\u5f15\u6570\u3092\u6301\u3064\u30af\u30e9\u30b9\u3092\u6307\u5b9a\u3059\u308b<span>\u2026<\/span>\u3068\u3044\u3046\u3088\u3046\u306a\u3001\u30cd\u30b9\u30c8\u3057\u305f\u578b\u5f15\u6570\u3082\u4f7f\u3048\u308b\u306e\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u5909\u6570\u3092\u5ba3\u8a00\u3059\u308b\u6642\u3001Map&lt;K, V&gt;\u306eK\u3068V\u306b\u4f55\u3092\u66f8\u304f\u304b\u3067\u3001Map\u3067\u6271\u3048\u308b\u30ad\u30fc\u3068\u5024\u3092\u6307\u5b9a\u3067\u304d\u308b\r\nMap map0; \/\/ \u2192 \u30ad\u30fc\u306fObject\u3001\u5024\u3082Object(Java 1.4\u307e\u3067\u306e\u66f8\u304d\u65b9)\r\nMap&lt;Object, Object&gt; map1; \/\/ \u2192 \u30ad\u30fc\u306fObject\u3001\u5024\u3082Object\r\nMap&lt;String, Integer&gt; map2; \/\/ \u2192 \u30ad\u30fc\u306fString\u3001\u5024\u306fInteger\r\nMap&lt;Integer, String&gt; map3; \/\/ \u2192 \u30ad\u30fc\u306fInteger\u3001\u5024\u306fString\r\nMap&lt;String, List&lt;String&gt;&gt; map4; \/\/ \u2192 \u30ad\u30fc\u306fString\u3001\u5024\u306fString\u3092\u6301\u3064List\r\nMap&lt;String, Map&lt;Integer, Object&gt;&gt; map5; \/\/ \u2192 \u30ad\u30fc\u306fString\u3001\u5024\u306f\u30ad\u30fc\u306bInteger\u30fb\u5024\u306bObject\u3092\u6301\u3064Map\r\nMap&lt;?, ?&gt; map6; \/\/ \u2192 \u30ad\u30fc\u306f\u306a\u3093\u3067\u3082\u3044\u3044\u3001\u5024\u3082\u306a\u3093\u3067\u3082\u3044\u3044<\/pre>\n<h4>\uff12-\uff11-\uff12\uff0e\u578b\u5f15\u6570\u3092\u4f7f\u3063\u305f<span>Map<\/span>\u306f\u4f7f\u3044\u3084\u3059\u3044<\/h4>\n<p>\u578b\u5f15\u6570\u3092\u6307\u5b9a\u3059\u308c\u3070\u3001<span>Map<\/span>\u304c\u30ad\u30fc\u3084\u5024\u3068\u3057\u3066\u4f55\u3092\u6271\u3046\u306e\u304b\u3001\u898b\u308c\u3070\u3059\u3050\u306b\u308f\u304b\u308a\u307e\u3059\u3002\u305d\u308c\u306b\u3001\u5024\u3092<span>get<\/span>\u3059\u308b\u6642\u306b\u30ad\u30e3\u30b9\u30c8\u304c\u3044\u308a\u307e\u305b\u3093\u3057\u3001\u578b\u5f15\u6570\u3067\u6307\u5b9a\u3057\u305f\u4ee5\u5916\u306e\u30af\u30e9\u30b9\u3092\u30ad\u30fc\u30fb\u5024\u3068\u3057\u3066<span>put<\/span>\u3057\u3088\u3046\u3068\u3059\u308b\u3068\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u30a8\u30e9\u30fc\u306b\u3057\u3066\u304f\u308c\u307e\u3059\u3002\u3067\u3059\u304b\u3089\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u54c1\u8cea\u5411\u4e0a\u306b\u3082\u5927\u304d\u304f\u7e4b\u304c\u308b\u306e\u3067\u3059<span>!!<\/span><\/p>\n<pre class=\"prettyprint lang:default decode:true\">Map map0 = new HashMap(); \/\/ \u2192 \u30ad\u30fc\u306fObject\u3001\u5024\u3082Object(Java 1.4\u307e\u3067\u306e\u66f8\u304d\u65b9)\r\nMap&lt;Object, Object&gt; map1 = new HashMap(); \/\/ \u2192 \u30ad\u30fc\u306fObject\u3001\u5024\u3082Object\r\nMap&lt;String, Integer&gt; map2 = new HashMap(); \/\/ \u2192 \u30ad\u30fc\u306fString\u3001\u5024\u306fInteger\r\n\r\nList value0 = (List) map0.get(\"\u30ad\u30fc\"); \/\/ \u672c\u5f53\u306b\u5024\u304cList\u304b\u306f\u3001\u52d5\u304b\u3055\u306a\u3044\u3068\u308f\u304b\u3089\u306a\u3044!!\r\nString value1 = (String) map1.get(\"\u30ad\u30fc\"); \/\/ \u5024\u304cObject\u3060\u3068\u3001\u5b9f\u969b\u306b\u5165\u3063\u3066\u3044\u308b\u30af\u30e9\u30b9\u3078\u306e\u30ad\u30e3\u30b9\u30c8\u304c\u5fc5\u8981\r\nInteger value2 = map2.get(\"\u30ad\u30fc\"); \/\/ \u578b\u5f15\u6570\u3067\u5024\u306e\u30af\u30e9\u30b9\u304c\u6307\u5b9a\u3067\u304d\u3066\u3044\u308c\u3070\u3001\u30ad\u30e3\u30b9\u30c8\u304c\u3044\u3089\u306a\u3044!!\r\nmap2.put(\"\u30ad\u30fc\", \"\u5024\"); \/\/ \u2192 \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u3001\u5024\u306bInteger\u3067\u306f\u306a\u3044String\u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u308b\u305f\u3081<\/pre>\n<h3><span id=\"-put\">\uff12-\uff12\uff0eput\u3067\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u308b<\/span><\/h3>\n<p>Map.put\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u3078\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u307e\u3059\u3002\u65e2\u306b\u30ad\u30fc\u304c<span>Map<\/span>\u306b\u3042\u308b\u5834\u5408\u306f\u3001\u65b0\u3057\u3044\u5bfe\u5fdc\u4ed8\u3051\u3067\u4e0a\u66f8\u304d\u3055\u308c\u307e\u3059\u3002\u30ad\u30fc\u3084\u5024\u3068\u3057\u3066<span>null<\/span>\u304c\u4f7f\u3048\u308b\u304b\u306f\u3001<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u6b21\u7b2c\u3067\u3059\u306e\u3067\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>put\u3067\u30ad\u30fc\u3068\u3059\u308b\u30af\u30e9\u30b9\u306f\u3001\u5c11\u306a\u304f\u3068\u3082<span>equals<\/span>\u304c\u304d\u3061\u3093\u3068\u52d5\u4f5c\u3059\u308b\u3088\u3046\u306b\u4f5c\u3089\u308c\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002\u305d\u3046\u3067\u306a\u3051\u308c\u3070\u3001\u30ad\u30fc\u304c\u540c\u3058\u304b\u3069\u3046\u304b\u3092<span>Map<\/span>\u304c\u5224\u65ad\u3067\u304d\u305a\u3001<span>get<\/span>\u306a\u3069<span>Map<\/span>\u5168\u4f53\u306e\u52d5\u4f5c\u306b\u5f71\u97ff\u3057\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nV put(K key, V value)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u6307\u5b9a\u3055\u308c\u305f\u5024\u304c\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u30ad\u30fc\r\n\tvalue - \u6307\u5b9a\u3055\u308c\u305f\u9375\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u5024\r\n\u623b\u308a\u5024:\r\n\tkey\u306b\u4ee5\u524d\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u3066\u3044\u305f\u5024\u3002key\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u304c\u5b58\u5728\u3057\u306a\u304b\u3063\u305f\u5834\u5408\u306fnull\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\"); \/\/ \u2192 \"\u732b\" \u306b \"\u30de\u30a4\u30b1\u30eb\" \u3092\u5bfe\u5fdc\u4ed8\u3051\u308b\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\"); \/\/ \u2192 \"\u72ac\" \u306b \"\u4f38\u4e4b\u52a9\" \u3092\u5bfe\u5fdc\u4ed8\u3051\u308b\r\n\r\nString name = map.put(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\"); \/\/ \u2192 \u3053\u306eMap\u306e\"\u732b\"\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u3082\u306e\u3092\"\u30cb\u30e3\u30b8\u30e9\"\u306b\u5909\u3048\u308b\r\nSystem.out.println(name); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\u3001\u5165\u308c\u66ff\u3048\u308b\u524d\u306e\u5024<\/pre>\n<h3><span id=\"-get\">\uff12-\uff13\uff0eget\u3067\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u5024\u3092\u53d6\u308a\u51fa\u3059<\/span><\/h3>\n<p>Map.get\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u306b<span>put<\/span>\u3055\u308c\u3066\u3044\u308b\u30ad\u30fc\u30fb\u5024\u306e\u5bfe\u5fdc\u4ed8\u3051\u306e\u4e2d\u304b\u3089\u3001\u30ad\u30fc\u306b\u5bfe\u5fdc\u3059\u308b\u5024\u3092\u53d6\u308a\u51fa\u305b\u307e\u3059\u3002\u30ad\u30fc\u304c<span>put<\/span>\u3055\u308c\u3066\u3044\u306a\u3044\u5834\u5408\u306f<span>null<\/span>\u304c\u623b\u308a\u307e\u3059\u3002<\/p>\n<p>\u3053\u3053\u3067\u300c\u53d6\u308a\u51fa\u3059\u300d\u3068\u3044\u3046\u8868\u73fe\u3092\u3057\u307e\u3057\u305f\u304c\u3001<span>get<\/span>\u3057\u3066\u3082<span>Map<\/span>\u306e\u30ad\u30fc\u3068\u5024\u306e\u5bfe\u5fdc\u4ed8\u3051\u306f\u305d\u306e\u307e\u307e\u3067\u3059\u3002\u306a\u305c\u304b\u3068\u8a00\u3046\u3068\u3001<span>get<\/span>\u3067\u623b\u3063\u3066\u304f\u308b\u306e\u306f<span>Map<\/span>\u304c\u5024\u3068\u3057\u3066\u6301\u3064\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3078\u306e\u53c2\u7167\u3060\u304b\u3089\u3067\u3059\u3002\u3064\u307e\u308a\u3001<span>get<\/span>\u306f<span>Map<\/span>\u3078\u300c\u30ad\u30fc\u306b\u5bfe\u5fdc\u3059\u308b\u5024\u3092\u3061\u3087\u3063\u3068\u898b\u305b\u3066\u3088\u300d\u3068\u304a\u9858\u3044\u3059\u308b\u3088\u3046\u306a\u30cb\u30e5\u30a2\u30f3\u30b9\u306e\u64cd\u4f5c\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nV get(Object key)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u95a2\u9023\u4ed8\u3051\u3089\u308c\u305f\u5024\u304c\u8fd4\u3055\u308c\u308b\u9375\r\n\u623b\u308a\u5024:\r\n\t\u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u304c\u30de\u30c3\u30d7\u3055\u308c\u3066\u3044\u308b\u5024\u3002\u305d\u306e\u30ad\u30fc\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u304c\u3053\u306e\u30de\u30c3\u30d7\u306b\u542b\u307e\u308c\u3066\u3044\u306a\u3044\u5834\u5408\u306fnull<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nString name1 = map.get(\"\u732b\");\r\nSystem.out.println(name1); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\r\n\r\nString name2 = map.get(\"\u72f8\"); \/\/ \"\u72f8\" \u3068\u3044\u3046\u30ad\u30fc\u306fmap\u306b\u5b58\u5728\u3057\u306a\u3044\u304c\u3001\u30a8\u30e9\u30fc\u306b\u306f\u306a\u3089\u306a\u3044\r\nSystem.out.println(name2); \/\/ \u2192 null<\/pre>\n<h3><span id=\"-remove\">\uff12-\uff14\uff0eremove\u3067\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b<\/span><\/h3>\n<p>Map.remove\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u306b<span>put<\/span>\u3055\u308c\u3066\u3044\u308b\u30ad\u30fc\u3092\u524a\u9664\u3057\u307e\u3059\u3002\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b\u6642\u3001\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u5024\u304c\u3082\u3057\u3042\u308c\u3070\u3001<span>Map<\/span>\u304b\u3089\u3044\u3063\u3057\u3087\u306b\u524a\u9664\u3055\u308c\u307e\u3059\u3002\u30ad\u30fc\u304c<span>put<\/span>\u3055\u308c\u3066\u3044\u306a\u304f\u3066\u3082\u30a8\u30e9\u30fc\u306b\u306f\u306a\u308a\u307e\u305b\u3093\u3002<span>put<\/span>\u3055\u308c\u3066\u3044\u305f\u304b\u306f\u3001\u623b\u308a\u5024\u3067\u5206\u304b\u308a\u307e\u3059\u3002<\/p>\n<p>\u30ad\u30fc\u306f<span>Map<\/span>\u306b\u3042\u308b\u307e\u307e\u3068\u3057\u3066\u3001\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u3066\u3044\u308b\u5024\u3060\u3051\u3092\u524a\u9664\u3057\u305f\u3044\u306e\u306a\u3089\u3001\u540c\u3058\u30ad\u30fc\u3092\u4f7f\u3063\u3066<span>null<\/span>\u3067<span>put<\/span>\u3057\u76f4\u3057\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u5024\u306b<span>null<\/span>\u304c\u4f7f\u3048\u308b\u304b\u306f<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u6b21\u7b2c\u3067\u3059\u306e\u3067\u3001\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nV remove(Object key)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u30de\u30c3\u30d4\u30f3\u30b0\u304c\u30de\u30c3\u30d7\u304b\u3089\u524a\u9664\u3055\u308c\u308b\u30ad\u30fc\r\n\u623b\u308a\u5024:\r\n\tkey\u306b\u4ee5\u524d\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u3066\u3044\u305f\u5024\u3002key\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u304c\u5b58\u5728\u3057\u306a\u304b\u3063\u305f\u5834\u5408\u306fnull\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nString name1 = map.remove(\"\u732b\"); \/\/ map\u304b\u3089\"\u732b\"\u3092\u524a\u9664\u3059\u308b\r\nSystem.out.println(name1); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\u3001\u524a\u9664\u6642\u306b\u306f\"\u30de\u30a4\u30b1\u30eb\"\u304c\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u3066\u3044\u305f\r\n\r\nString name2 = map.get(\"\u732b\");\r\nSystem.out.println(name2); \/\/ \u2192 null\u3001\u30ad\u30fc\u304cremove\u3055\u308c\u3066\u3044\u308b\u306e\u3067get\u3057\u3066\u3082null\u306b\u306a\u308b\r\n\r\nString name3 = map.remove(\"\u72f8\"); \/\/ \"\u72f8\" \u3068\u3044\u3046\u30ad\u30fc\u306fmap\u306b\u5b58\u5728\u3057\u306a\u3044\u304c\u3001\u30a8\u30e9\u30fc\u306b\u306f\u306a\u3089\u306a\u3044\r\nSystem.out.println(name3); \/\/ \u2192 null<\/pre>\n<h3><span id=\"-clear\">\uff12-\uff15\uff0eclear\u3067\u3059\u3079\u3066\u306e\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b<\/span><\/h3>\n<p>Map.clear\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u306b<span>put<\/span>\u3055\u308c\u3066\u3044\u308b\u30ad\u30fc\u3092\u3059\u3079\u3066\u524a\u9664\u3057\u307e\u3059\u3002<span>Map<\/span>\u3092\u7a7a\u306b\u3057\u305f\u3044\u6642\u306b\u3001\u30ad\u30fc\u3092\u4e00\u3064\u4e00\u3064<span>remove<\/span>\u3057\u3066\u306f\u6642\u9593\u3082\u304b\u304b\u308a\u307e\u3059\u3057\u3001\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3082\u5927\u5909\u3067\u3059\u3002<span>clear<\/span>\u3092\u4f7f\u3063\u3066\u697d\u3092\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nvoid clear()\r\n\u30de\u30c3\u30d7\u304b\u3089\u30de\u30c3\u30d4\u30f3\u30b0\u3092\u3059\u3079\u3066\u524a\u9664\u3057\u307e\u3059(\u30aa\u30d7\u30b7\u30e7\u30f3\u306e\u64cd\u4f5c)\u3002\u3053\u306e\u547c\u51fa\u3057\u304c\u623b\u308b\u3068\u3001\u30de\u30c3\u30d7\u306f\u7a7a\u306b\u306a\u308a\u307e\u3059\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nmap.clear(); \/\/ map\u304b\u3089\u3059\u3079\u3066\u306e\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b\r\n\r\nString name1 = map.get(\"\u732b\");\r\nSystem.out.println(name1); \/\/ \u2192 null\u3001map\u304b\u3089\u30ad\u30fc\u304c\u524a\u9664\u3055\u308c\u305f\r\n\r\nString name2 = map.get(\"\u72ac\");\r\nSystem.out.println(name2); \/\/ \u2192 null\u3001\u540c\u4e0a<\/pre>\n<h3><span id=\"i\">\uff12-\uff16\uff0e\u30ad\u30fc\u3084\u5024\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<\/span><\/h3>\n<h4>\uff12-\uff16-\uff11\uff0eisEmpty\u3067\u7a7a\u3063\u307d\u304b\u78ba\u8a8d\u3059\u308b<\/h4>\n<p>Map.isEmpty\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u306b\u30ad\u30fc\u304c\u3042\u308b\u304b<span>boolean<\/span>\u3067\u5206\u304b\u308a\u307e\u3059\u3002\u30ad\u30fc\u3068\u5024\u306e\u5bfe\u5fdc\u4ed8\u3051\u304c\u4e00\u3064\u3067\u3082\u3042\u308b\u306a\u3089<span>true<\/span>\u3001\u306a\u3044\u306a\u3089<span>false<\/span>\u3067\u3059\u3002<span>keySet<\/span>\u3067\u623b\u3063\u3066\u304f\u308b<span>Set<\/span>\u306e<span>size<\/span>\u3067\u3082\u3044\u3044\u306e\u3067\u3059\u304c\u3001\u3053\u3061\u3089\u306e\u65b9\u304c\u884c\u3063\u3066\u3044\u308b\u3053\u3068\u306e\u610f\u5473\u304c\u660e\u78ba\u306b\u306a\u308a\u307e\u3059\u306e\u3067\u304a\u52e7\u3081\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nboolean isEmpty()\r\n\u623b\u308a\u5024:\r\n\t\u3053\u306e\u30de\u30c3\u30d7\u304c\u30ad\u30fc\u3068\u5024\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u3092\u4fdd\u6301\u3057\u306a\u3044\u5834\u5408\u306ftrue<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\n\r\nboolean isEmpty = map.isEmpty();\r\nSystem.out.println(isEmpty); \/\/ \u2192 true\r\n\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\"); \/\/ map\u306b\u30ad\u30fc\u3092\u8ffd\u52a0\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\nisEmpty = map.isEmpty();\r\nSystem.out.println(isEmpty); \/\/ \u2192 false\r\n\r\nmap.clear(); \/\/ map\u304b\u3089\u3059\u3079\u3066\u306e\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b\r\nisEmpty = map.isEmpty();\r\nSystem.out.println(isEmpty); \/\/ \u2192 true<\/pre>\n<h4>\uff12-\uff16-\uff12\uff0econtainsKey\u3067\u30ad\u30fc\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<\/h4>\n<p>Map.containsKey\u3067\u3001<span>Map<\/span>\u306b\u30ad\u30fc\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002<span>get<\/span>\u3057\u3066\u5024\u304c<span>null<\/span>\u304b\u78ba\u8a8d\u3059\u308b\u3084\u308a\u65b9\u3067\u3082\u3044\u3044\u306e\u3067\u3059\u304c\u3001\u5024\u304c<span>null<\/span>\u3060\u3063\u305f\u5834\u5408\u306b\u30ad\u30fc\u306e\u6709\u7121\u306e\u533a\u5225\u304c\u3064\u304d\u307e\u305b\u3093\u3002<span>Map<\/span>\u304c\u30ad\u30fc\u3092\u6301\u3063\u3066\u3044\u308b\u304b\u3092\u300c\u78ba\u5b9f\u306b\u300d\u5224\u65ad\u3057\u305f\u3044\u306e\u306a\u3089\u3001<span>containsKey<\/span>\u3092\u4f7f\u3044\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nboolean containsKey(Object key)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u3053\u306e\u30de\u30c3\u30d7\u5185\u306b\u3042\u308b\u304b\u3069\u3046\u304b\u304c\u5224\u5b9a\u3055\u308c\u308b\u30ad\u30fc\r\n\u623b\u308a\u5024:\r\n\t\u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u304c\u3053\u306e\u30de\u30c3\u30d7\u306b\u542b\u307e\u308c\u3066\u3044\u308b\u5834\u5408\u306ftrue<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nboolean contains1 = map.containsKey(\"\u732b\");\r\nSystem.out.println(cotnains1); \/\/ \u2192 true\u3001\u30ad\u30fc\"\u732b\"\u306fmap\u306b\u3042\u308b\r\n\r\nboolean contains2 = map.containsKey(\"\u72ac\");\r\nSystem.out.println(cotnains2); \/\/ \u2192 true\u3001\u30ad\u30fc\"\u72ac\"\u306fmap\u306b\u3042\u308b\r\n\r\nboolean contains3 = map.containsKey(\"\u72f8\");\r\nSystem.out.println(cotnains3); \/\/ \u2192 false\u3001\u30ad\u30fc\"\u72f8\"\u306fmap\u306b\u306a\u3044<\/pre>\n<h4>\uff12-\uff16-\uff13\uff0econtainsValue\u3067\u5024\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b<\/h4>\n<p>Map.containsValue\u3067\u3001<span>Map<\/span>\u306b\u5024\u304c\u3042\u308b\u304b\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002<span>containsValue<\/span>\u306e\u5f15\u6570\u3067\u6e21\u3057\u305f\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3068\u3001<span>equals<\/span>\u3067<span>true<\/span>\u306b\u306a\u308b\u5024\u304c\u5c11\u306a\u304f\u3068\u3082\u4e00\u3064\u3042\u308b\u304b\u3092\u8abf\u3079\u307e\u3059\u3002\u3067\u3059\u304b\u3089\u3001\u5024\u306b\u4f7f\u3046\u30af\u30e9\u30b9\u304c<span>equals<\/span>\u3092\u304d\u3061\u3093\u3068\u4f5c\u3063\u3066\u3042\u308b\u304b\u304c\u3068\u3066\u3082\u5927\u4e8b\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nboolean containsValue(Object value)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tvalue - \u3053\u306e\u30de\u30c3\u30d7\u306b\u3042\u308b\u304b\u3069\u3046\u304b\u304c\u5224\u5b9a\u3055\u308c\u308b\u5024\r\n\u623b\u308a\u5024:\r\n\t\u3053\u306e\u30de\u30c3\u30d7\u304c1\u3064\u307e\u305f\u306f\u8907\u6570\u306e\u30ad\u30fc\u3092\u6307\u5b9a\u3055\u308c\u305f\u5024\u306b\u30de\u30c3\u30d4\u30f3\u30b0\u3057\u3066\u3044\u308b\u5834\u5408\u306ftrue<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\nmap.put(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\", \"\u30de\u30a4\u30b1\u30eb\");\r\n\r\nboolean contains1 = map.containsValue(\"\u30de\u30a4\u30b1\u30eb\");\r\nSystem.out.println(cotnains1); \/\/ \u2192 true\u3001\u5024\"\u30de\u30a4\u30b1\u30eb\"\u306fmap\u306b\u3042\u308b\r\n\r\nboolean contains2 = map.containsValue(\"\u4f38\u4e4b\u52a9\");\r\nSystem.out.println(cotnains2); \/\/ \u2192 true\u3001\u5024\"\u4f38\u4e4b\u52a9\"\u306fmap\u306b\u3042\u308b\r\n\r\nboolean contains3 = map.containsValue(\"\u30cb\u30e3\u30b8\u30e9\");\r\nSystem.out.println(cotnains3); \/\/ \u2192 false\u3001\u5024\"\u30cb\u30e3\u30b8\u30e9\"\u306fmap\u306b\u306a\u3044<\/pre>\n<h3><span id=\"-SetCollection\">\uff12-\uff17\uff0e\u30ad\u30fc\u3084\u5024\u3092<span>Set<\/span>\u3084<span>Collection<\/span>\u3067\u53d6\u308a\u51fa\u3059<\/span><\/h3>\n<p>Map\u306e\u5916\u90e8\u304b\u3089\u3001\u6301\u3063\u3066\u3044\u308b\u30ad\u30fc\u3084\u5024\u306e\u4e00\u89a7\u3092\u81ea\u7531\u306b\u53d6\u308a\u51fa\u305b\u307e\u3059\u3002\u305d\u3046\u3057\u3066\u53d6\u308a\u51fa\u3057\u305f\u7d50\u679c\u306f<span>Set<\/span>\u3084<span>Collection<\/span>\u3068\u306a\u308b\u306e\u3067\u3059\u304c\u3001\u53d6\u308a\u51fa\u3057\u305f\u5143\u306e<span>Map<\/span>\u3068\u9023\u52d5\u3057\u3066\u3044\u308b\u306e\u3067\u64cd\u4f5c\u3059\u308b\u6642\u306f\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002\u3069\u3093\u306a\u611f\u3058\u3067\u9023\u52d5\u3057\u3066\u3044\u308b\u304b\u306f\u3001\u5225\u306e\u7ae0\u3067\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002<\/p>\n<h4>\uff12-\uff17-\uff11\uff0ekeySet\u3067\u30ad\u30fc\u3092\u3059\u3079\u3066\u53d6\u5f97\u3059\u308b<\/h4>\n<p>Map.keySet\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u304c\u6301\u3063\u3066\u3044\u308b\u30ad\u30fc\u3092\u3059\u3079\u3066\u5024\u3068\u3057\u3066\u542b\u3080<span>Set<\/span>\u3092\u5f97\u3089\u308c\u307e\u3059\u3002\u30ad\u30fc\u3067\u30eb\u30fc\u30d7\u3092\u3057\u305f\u3044\u5834\u5408\u306a\u3069\u306b\u4f7f\u3044\u307e\u3059\u3002\u30ad\u30fc\u306e\u6570\u3092\u77e5\u308a\u305f\u3044\u306a\u3089\u3001\u7d50\u679c\u306e<span>Set<\/span>\u306e\u30e1\u30bd\u30c3\u30c9<span>size<\/span>\u3092\u4f7f\u3046\u3068\u3044\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nSet&lt;K&gt; keySet()\r\n\u623b\u308a\u5024:\r\n\t\u30de\u30c3\u30d7\u306b\u542b\u307e\u308c\u3066\u3044\u308b\u30ad\u30fc\u306e\u30bb\u30c3\u30c8\u30fb\u30d3\u30e5\u30fc<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nSet&lt;String&gt; keys = map.keySet();\r\nSystem.out.println(keys.size()); \/\/ \u2192 2\u3001map\u306b\u306f\u30ad\u30fc\u304c2\u3064\u3042\u308b\u305f\u3081\r\nSystem.out.println(keys); \/\/ \u2192 [\u732b, \u72ac]<\/pre>\n<h4>\uff12-\uff17-\uff12\uff0evalues\u3067\u5024\u3092\u3059\u3079\u3066\u53d6\u5f97\u3059\u308b<\/h4>\n<p>Map.values\u3092\u4f7f\u3046\u3068\u3001<span>Map<\/span>\u304c\u6301\u3063\u3066\u3044\u308b\u5024\u3092\u3059\u3079\u3066\u542b\u3080<span>Collection<\/span>\u3092\u5f97\u3089\u308c\u307e\u3059\u3002\u5024\u3060\u3051\u304c\u6b32\u3057\u3044\u5834\u5408\u306a\u3069\u306b\u4f7f\u3044\u307e\u3059\u3002\u30ad\u30fc\u306e\u6570\u3092\u77e5\u308a\u305f\u3044\u306a\u3089\u3001\u7d50\u679c\u306e<span>Collection<\/span>\u306e\u30e1\u30bd\u30c3\u30c9<span>size<\/span>\u3092\u4f7f\u3046\u3068\u3044\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<p>\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u6642\u306b\u610f\u8b58\u3057\u305f\u3044\u306e\u306f\u3001\u623b\u308a\u5024\u306f\u6301\u3063\u3066\u3044\u308b\u8981\u7d20\u304c\u4e00\u610f\u306b\u306a\u308b<span>Set<\/span>\u3067\u306f\u306a\u304f\u3001\u305f\u3060\u306e\u8981\u7d20\u306e\u96c6\u307e\u308a\u3067\u3042\u308b<span>Collection<\/span>\u3060\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002\u3064\u307e\u308a\u3001\u7570\u306a\u308b\u30ad\u30fc\u3067\u540c\u3058\u5024\u3092\u542b\u3093\u3067\u3044\u3066\u3082\u3001\u623b\u308a\u5024\u306e<span>Collection<\/span>\u306b\u306f\u9055\u3046\u8981\u7d20\u3068\u3057\u3066\u542b\u307e\u308c\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nCollection&lt;V&gt; values()\r\n\u623b\u308a\u5024:\r\n\t\u30de\u30c3\u30d7\u5185\u306b\u542b\u307e\u308c\u3066\u3044\u308b\u5024\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u30fb\u30d3\u30e5\u30fc<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\nmap.put(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\", \"\u30de\u30a4\u30b1\u30eb\");\r\n\r\nCollection&lt;String&gt; values = map.values();\r\nSystem.out.println(values.size()); \/\/ \u2192 3\u3001map\u306b\u306f\u5024\u304c\u300c3\u3064\u300d\u3042\u308b\u305f\u3081\r\nSystem.out.println(values); \/\/ \u2192 [\u30de\u30a4\u30b1\u30eb, \u30de\u30a4\u30b1\u30eb, \u4f38\u4e4b\u52a9]<\/pre>\n<h4>\uff12-\uff17-\uff13\uff0eentrySet\u3067<span>Map<\/span>\u304c\u6301\u3064\u30ad\u30fc\u30fb\u5024\u3092\u3059\u3079\u3066\u53d6\u5f97\u3059\u308b<\/h4>\n<p>Map.entrySet\u3092\u4f7f\u3046\u3068\u3001\u30ad\u30fc\u3068\u5024\u3092\u30da\u30a2\u3067\u6301\u3064<span>Map<\/span>\u306e\u5185\u90e8\u30af\u30e9\u30b9<span>Map.Entry<\/span>\u306e<span>Set<\/span>\u3092\u5f97\u3089\u308c\u307e\u3059\u3002<span>keySet<\/span>\u3084<span>values<\/span>\u306f\u30ad\u30fc\u30fb\u5024\u3060\u3051\u3067\u3057\u305f\u304c\u3001\u3053\u3061\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u4e21\u65b9\u4e00\u5ea6\u306b\u5f97\u3089\u308c\u308b\u306e\u304c\u7570\u306a\u308b\u3068\u3053\u308d\u3067\u3059\u3002<\/p>\n<p>Map.Entry\u306f\u3001<span>getKey<\/span>\u3067\u30ad\u30fc\u3092\u3001<span>getValue<\/span>\u3067\u5024\u3092\u53d6\u5f97\u3067\u304d\u307e\u3059\u3002\u3067\u3059\u306e\u3067\u3001\u3053\u306e\u30da\u30a2\u3067<span>Map<\/span>\u306b\u767b\u9332\u3055\u308c\u3066\u3044\u308b\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nSet&lt;Map.Entry&lt;K,V&gt;&gt; entrySet()\r\n\u623b\u308a\u5024:\r\n\t\u30de\u30c3\u30d7\u5185\u306b\u4fdd\u6301\u3055\u308c\u3066\u3044\u308b\u30de\u30c3\u30d4\u30f3\u30b0\u306e\u30bb\u30c3\u30c8\u30fb\u30d3\u30e5\u30fc<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\nmap.put(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\", \"\u30de\u30a4\u30b1\u30eb\");\r\n\r\nSet&lt;Map.Entry&lt;String, String&gt;&gt; entries = map.entrySet();\r\nSystem.out.println(entries.size()); \/\/ \u2192 3\u3001map\u306b\u306f\u30ad\u30fc\u3068\u5024\u306e\u30da\u30a2\u304c3\u3064\u3042\u308b\u305f\u3081\r\nSystem.out.println(entries); \/\/ \u2192 [\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b=\u30de\u30a4\u30b1\u30eb, \u732b=\u30de\u30a4\u30b1\u30eb, \u72ac=\u4f38\u4e4b\u52a9]\r\n\r\nfor (Map.Entry&lt;String, String&gt; entry : entries) {\r\n\tSystem.out.println(\"\u30ad\u30fc\u306f[\" + entry.getKey() + \"]\u3001\u5024\u306f[\" + entry.getValue() + \"]\u3067\u3059\");\r\n}<\/pre>\n<h2><span id=\"Map\">\uff13\uff0e\u3010\u5fdc\u7528\u3011Map\u306e\u6d3b\u7528\u65b9\u6cd5\u3044\u308d\u3044\u308d<\/span><\/h2>\n<p>\u30ad\u30fc\u3068\u5024\u3092\u4f7f\u3063\u3066\u30c7\u30fc\u30bf\u3092<span>Map<\/span>\u306e\u4e2d\u306b\u4fdd\u5b58\u3059\u308b<span>\u2026<\/span>\u3068\u8a00\u308f\u308c\u3066\u3082\u3001\u5177\u4f53\u7684\u306a\u6d3b\u7528\u65b9\u6cd5\u304c\u601d\u3044\u6d6e\u304b\u3070\u306a\u3044\u65b9\u3082\u3044\u3089\u3063\u3057\u3083\u308b\u3067\u3057\u3087\u3046\u3002\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u521d\u5fc3\u8005\u306a\u3089\u3001\u3080\u3057\u308d\u305d\u308c\u304c\u666e\u901a\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u7ae0\u3067\u306f\u3001\u5b9f\u969b\u306e<span>Java<\/span>\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u306e<span>Map<\/span>\u306e\u4f7f\u7528\u4f8b\u3092\u3044\u304f\u3064\u304b\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002<\/p>\n<h3><span id=\"i-2\">\uff13-\uff11\uff0e\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u30fb\u5206\u985e\u30fb\u52a0\u5de5\u306b\u4f7f\u3046<\/span><\/h3>\n<p>Map\u306f\u30c7\u30fc\u30bf\u3092\u30e1\u30e2\u30ea\u4e0a\u3067\u96c6\u8a08\u30fb\u5206\u985e\u30fb\u52a0\u5de5\u3059\u308b\u6642\u306b\u3088\u304f\u4f7f\u3044\u307e\u3059\u3002\u30ad\u30fc\u3092\u96c6\u8a08\u30ad\u30fc\u3068\u3057\u3066\u3001\u5024\u3092\u96c6\u8a08\u7d50\u679c\u306b\u3057\u307e\u3059\u3002<\/p>\n<p>SQL\u3092\u3054\u5b58\u3058\u306a\u3089\u3001<span>GROUP BY<\/span>\u3092\u3059\u308b\u5217\u304c\u30ad\u30fc\u3001<span>SUM<\/span>\u3084<span>AVG<\/span>\u3057\u305f\u7d50\u679c\u304c\u5024\u3068\u306a\u308b\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002\u3082\u3061\u308d\u3093\u3001\u96c6\u8a08\u306e\u65b9\u6cd5\u306f\u81ea\u7531\u306b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u304d\u307e\u3059\u304b\u3089\u3001\u5fdc\u7528\u306e\u65b9\u5411\u6027\u306f\u8272\u3005\u3067\u3059\u3002<\/p>\n<p>\u5b9f\u7528\u4e0a\u3067\u306f\u3001\u30ad\u30fc\u306b\u306f<span>String<\/span>\u304c\u3088\u304f\u4f7f\u308f\u308c\u307e\u3059\u3002\u3082\u3061\u308d\u3093\u3001\u30ad\u30fc\u3068\u306a\u308a\u5f97\u308b\u306a\u3089\u5225\u306e\u30af\u30e9\u30b9\u3067\u3082<span>OK<\/span>\u3067\u3059\u3002\u5024\u3068\u3057\u3066\u306f\u3001\u96c6\u8a08\u7d50\u679c\u306f\u4f55\u304b\u3092\u8db3\u3057\u3053\u3081\u308b\u3088\u3046\u306a\u5024<span>(<\/span>\u6570\u5024\u306e\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u306a\u3069<span>)<\/span>\u3084\u30af\u30e9\u30b9\u306b\u3057\u3066\u304a\u304f\u3068\u3044\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<p>\u96c6\u8a08\u51e6\u7406\u3067\u306f\u3001<span>Map<\/span>\u306b\u30ad\u30fc\u304c\u306a\u3051\u308c\u3070\u65b0\u3057\u304f<span>put<\/span>\u3057\u3001\u3042\u308c\u3070\u5024\u3078\u4f55\u304b\u306e\u51e6\u7406\u3092\u3057\u3066\u66f4\u65b0\u5f8c\u306e\u5024\u3067<span>put<\/span>\u3092\u3057\u307e\u3059\u3002\u3053\u308c\u306f<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u306e\u30a4\u30c7\u30a3\u30aa\u30e0\u3067\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">List&lt;String&gt; data = Arrays.asList(\"A,100\", \"B,50\", \"C,200\", \"A,150\", \"B,1000\"); \/\/ \u30ad\u30fc\u6587\u5b57\u5217\u3001\u5024\u3092\u6301\u3063\u305f\u30c7\u30fc\u30bf\r\nMap&lt;String, Integer&gt; groupBy = new HashMap&lt;&gt;(); \/\/ \u30ad\u30fc\u306fString\u3001\u5024\u306f\u6570\u5b57\u3092\u5408\u8a08\u3059\u308b\u306e\u3067Integer\u3068\u3057\u3066\u3044\u308b\r\n\r\nfor (String d : data) {\r\n\tString[] items = d.split(\",\");\r\n\tInteger num = Integer.valueOf(items[1]);\r\n\tInteger sum = groupBy.get(items[0]);\r\n\r\n\tif (sum == null) {\r\n\t\tgroupBy.put(items[0], num);\r\n\t} else {\r\n\t\tsum += num;\r\n\t\tgroupBy.put(items[0], sum);\r\n\t}\r\n}\r\n\r\nSystem.out.println(groupBy.get(\"A\")); \/\/ \u2192 250<\/pre>\n<p>\u96c6\u8a08\u7d50\u679c\u3092\u5408\u8a08\u3059\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u5358\u306b\u30b0\u30eb\u30fc\u30d7\u5316\u3057\u305f\u3044\u306a\u3089\u3001<span>List<\/span>\u306a\u3069\u3092\u5024\u3068\u3059\u308c\u3070\u3088\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<p>\u306a\u304a\u3001\u4ee5\u4e0b\u306e\u4f8b\u306e\u3088\u3046\u306b\u3001\u5024\u304c\u30af\u30e9\u30b9\u306a\u3089<span>get<\/span>\u3067\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3078\u306e\u53c2\u7167\u304c\u5f97\u3089\u308c\u307e\u3059\u306e\u3067\u3001\u3042\u3089\u305f\u3081\u3066<span>put<\/span>\u3057\u76f4\u3059\u5fc5\u8981\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3053\u3053\u3082<span>Map<\/span>\u3067\u6c17\u3092\u4ed8\u3051\u305f\u3044\u3068\u3053\u308d\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">List&lt;String&gt; data = Arrays.asList(\"A,100\", \"B,50\", \"C,200\", \"A,150\", \"B,1000\"); \/\/ \u30ad\u30fc\u6587\u5b57\u5217\u3001\u5024\u3092\u6301\u3063\u305f\u30c7\u30fc\u30bf\r\nMap&lt;String, List&lt;Integer&gt;&gt; groupBy = new HashMap&lt;&gt;(); \/\/ \u30ad\u30fc\u306fString\u3001\u5024\u306f\u6570\u5b57\u3092\u96c6\u3081\u308b\u306e\u3067Integer\u306eList\u3068\u3057\u305f\r\n\r\nfor (String d : data) {\r\n\tString[] items = d.split(\",\");\r\n\tInteger num = Integer.valueOf(items[1]);\r\n\tList&lt;Integer&gt; sum = groupBy.get(items[0]);\r\n\r\n\tif (sum == null) {\r\n\t\tsum = new ArrayList&lt;&gt;();\r\n\t\tgroupBy.put(items[0], sum);\r\n\t}\r\n\r\n\tsum.add(num);\r\n}\r\n\r\nSystem.out.println(groupBy.get(\"A\")); \/\/ \u2192 [100, 150]<\/pre>\n<h3><span id=\"i-3\">\uff13-\uff12\uff0e\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u7c21\u6613\u7684\u306a\u8868\u73fe\u306b\u4f7f\u3046<\/span><\/h3>\n<p>Map\u306e\u30ad\u30fc\u306b\u306a\u308b<span>String<\/span>\u306e\u4e00\u89a7\u3092\u3042\u3089\u304b\u3058\u3081\u6c7a\u3081\u3066\u304a\u3051\u3070\u3001\u30af\u30e9\u30b9\u306e\u4ee3\u308f\u308a\u306b\u4f7f\u3048\u308b\u7c21\u6613\u7684\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3068\u3057\u3066\u4f7f\u3048\u307e\u3059\u3002\u30af\u30e9\u30b9\u3092\u4f5c\u308b\u307b\u3069\u3067\u3082\u306a\u3044\u5834\u5408\u3084\u3001\u30c7\u30fc\u30bf\u3092\u6e21\u3059\u5148\u304c\u30cd\u30c3\u30c8\u30ef\u30fc\u30af\u306e\u5411\u3053\u3046\u5074\u306b\u3042\u3063\u3066\u30af\u30e9\u30b9\u3067\u3084\u308a\u53d6\u308a\u3067\u304d\u306a\u3044\u5834\u5408\u306a\u3069\u3067\u4f7f\u3048\u308b\u3067\u3057\u3087\u3046\u3002\u5834\u5408\u306b\u3088\u3063\u3066\u306f\u3001<span>Map<\/span>\u304c\u30cd\u30b9\u30c8\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Map\u3067\u30e6\u30fc\u30b6\u306e\u60c5\u5831\u3092\u8868\u73fe\u3057\u3066\u307f\u308b\r\nMap&lt;String, Object&gt; userAttribute = new HashMap&lt;&gt;();\r\nuserAttribute.put(\"userId\", 100);\r\nuserAttribute.put(\"userName\", \"\u30de\u30a4\u30b1\u30eb\");\r\nuserAttribute.put(\"mailAddress\", \"michael@example.com\");\r\nuserAttribute.put(\"birthday\", LocalDate.of(2019, 1, 1));\r\nuserAttribute.put(\"trait\", Arrays.asList(\"\u732b\", \"\u3082\u3075\u3082\u3075\"));\r\n\r\n\/\/ \u30e6\u30fc\u30b6\u306e\u60c5\u5831\u3092\u7ba1\u7406\u3059\u308bMap\u3092\u5225\u306b\u4f5c\u308a\u3001\u6570\u5024\u306e\u30e6\u30fc\u30b6ID\u3092\u30ad\u30fc\u306b\u3057\u3066Map\u3092\u5024\u3068\u3057\u3066\u5bfe\u5fdc\u4ed8\u3051\u308b\r\nMap&lt;Integer, Map&lt;String, Object&gt;&gt; users = new HashMap&lt;&gt;();\r\nusers.put(100, userAttribute);\r\n\r\n\/\/ \u30e6\u30fc\u30b6\u60c5\u5831\u3092\u6301\u3063\u3066\u3044\u308bMap\u3092\u3053\u3093\u306a\u611f\u3058\u3067\u4f7f\u3046\r\nSystem.out.println(users.get(100).get(\"userName\")); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"<\/pre>\n<p>\u3053\u306e\u5834\u5408\u306b\u91cd\u8981\u306a\u306e\u306f\u3001<span>Map<\/span>\u306b\u306f\u3069\u3046\u3044\u3046\u30ad\u30fc\u3068\u5024\u304c\u3042\u308b\u304b\u3068\u3044\u3046\u53d6\u308a\u6c7a\u3081\u3067\u3059\u3002<span>Map<\/span>\u306e\u69cb\u9020\u3092<span>Javadoc<\/span>\u3084\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u4ed5\u69d8\u66f8\u306a\u3069\u3067\u660e\u78ba\u306b\u3057\u3066\u304a\u304f\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u7279\u306b\u3001<span>Map<\/span>\u3092\u6c4e\u7528\u7684\u306a\u69cb\u9020\u3068\u3057\u3066\u4f7f\u3046\u306a\u3089\u3001\u3053\u306e\u4f8b\u306e\u3088\u3046\u306b\u5024\u304c<span>Object<\/span>\u306b\u306a\u308a\u304c\u3061\u306a\u306e\u3067\u3001\u30ad\u30fc\u306e\u5024\u304c\u4f55\u306a\u306e\u304b\u306f\u4e8b\u524d\u306b\u660e\u78ba\u306b\u3057\u3066\u304a\u304d\u307e\u3059\u3002<\/p>\n<h4>\uff13-\uff12-\uff11\uff0e\u3010\u53c2\u8003\u3011<span>Map<\/span>\u306e\u30ad\u30fc\u3068\u5024\u306b\u306f\u7528\u9014\u306b\u9069\u3057\u305f\u30af\u30e9\u30b9\u304c\u597d\u307e\u3057\u3044<\/h4>\n<p>\u305f\u3060\u3001\u3053\u3046\u3044\u3046\u7528\u9014\u3067\u3082\u3001\u30ad\u30fc\u3084\u5024\u306b\u72ec\u81ea\u306e\u30af\u30e9\u30b9\u3092\u4f7f\u3046\u65b9\u304c\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u5206\u304b\u308a\u3084\u3059\u304f\u306a\u308b\u30b1\u30fc\u30b9\u304c\u591a\u3044\u3067\u3059\u3002\u9069\u5207\u306a\u5909\u6570\u540d\u3084\u30e1\u30bd\u30c3\u30c9\u304c\u4f7f\u3048\u308c\u3070\u610f\u5473\u304c\u5206\u304b\u308a\u3084\u3059\u304f\u306a\u308a\u307e\u3059\u3057\u3001\u578b\u304c\u660e\u78ba\u306b\u306a\u308b\u306e\u3067\u30b3\u30f3\u30d1\u30a4\u30e9\u30ec\u30d9\u30eb\u3067\u30c1\u30a7\u30c3\u30af\u304c\u3067\u304d\u308b\u306a\u3069\u3001\u30e1\u30ea\u30c3\u30c8\u304c\u591a\u3044\u3082\u306e\u3067\u3059\u3002<\/p>\n<p>\u305d\u308c\u306b\u3001<span>Map<\/span>\u3092\u4f7f\u3046\u7bc4\u56f2\u304c\u30af\u30e9\u30b9\u306e\u4e2d\u306b\u9589\u3058\u3066\u3044\u308b\u306a\u3089\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u5185\u90e8\u30af\u30e9\u30b9\u3092\u7a4d\u6975\u7684\u306b\u4f5c\u3063\u3066\u5229\u7528\u3059\u308b\u306e\u304c\u3001<span>Java<\/span>\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30bf\u30a4\u30eb\u3067\u3059\u3002\u305f\u3060\u3001\u305d\u3046\u3044\u3046\u5185\u90e8\u30af\u30e9\u30b9\u306f\u30af\u30e9\u30b9\u306e\u5916\u90e8\u304b\u3089\u898b\u3048\u306a\u3044\u30fb\u4f7f\u3048\u306a\u3044\u3088\u3046\u306b\u3057\u306a\u3044\u3068\u6df7\u4e71\u3092\u62db\u304d\u307e\u3059\u306e\u3067\u3001\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<h3><span id=\"i-4\">\uff13-\uff13\uff0e\u30c7\u30fc\u30bf\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u4f7f\u3046<\/span><\/h3>\n<p>\u30ad\u30fc\u3068\u306a\u308b\u60c5\u5831\u306f\u5c11\u6570\u3067\u660e\u78ba\u3001\u305d\u306e\u4e00\u65b9\u3067\u5024\u306f\u8907\u96d1\u3067\u4f5c\u308b\u306e\u306b\u624b\u9593\u3082\u6642\u9593\u3082\u304b\u304b\u308b<span>\u2026<\/span>\u305d\u3093\u306a\u5834\u5408\u306f\u3001<span>Map<\/span>\u3092\u5024\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3068\u3057\u3066\u4f7f\u3048\u307e\u3059\u3002<\/p>\n<p>\u3088\u304f\u4f7f\u3046\u306e\u306f\u3001\u30ad\u30fc\u3068\u3057\u305f\u3044\u8907\u6570\u306e<span>String<\/span>\u3092\u3001\u4f55\u304b\u306e\u30bb\u30d1\u30ec\u30fc\u30bf<span>(<\/span>\u30ad\u30fc\u5185\u3067\u4f7f\u308f\u308c\u306a\u3044\u6587\u5b57\u304c\u597d\u307e\u3057\u3044<span>)<\/span>\u3067\u7e4b\u3044\u3060\u3082\u306e\u3092\u3001<span>Map<\/span>\u306e\u30ad\u30fc\u3068\u3059\u308b\u3053\u3068\u3067\u3059\u3002\u3042\u308b\u3044\u306f\u3001\u30ad\u30fc\u60c5\u5831\u305d\u306e\u3082\u306e\u3092\u30af\u30e9\u30b9\u306b\u3057\u3066\u3057\u307e\u3048\u308b\u306a\u3089\u3001\u4ed6\u3067\u3082\u3044\u308d\u3044\u308d\u3068\u6d41\u7528\u304c\u3067\u304d\u307e\u3059\u306e\u3067\u3001\u3088\u308a\u826f\u3044\u3084\u308a\u65b9\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u30ad\u30fc\u304c2\u3064\u306eString\u3067\u8868\u73fe\u3067\u304d\u308b\u5834\u5408\r\nprivate Map&lt;String, VeryComplexClass&gt; cache = new HashMap&lt;&gt;(); \/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u3068\u3057\u3066\u4f7f\u3046Map\u3092\u4f5c\u308b\u3002\u5185\u5bb9\u306f\u521d\u671f\u72b6\u614b\u3067\u306f\u7a7a\u3002\r\n\r\npublic VeryComplexClass getVeryComplexClass(String key1, String key2) {\r\n\tString key = key1 + \"\\t\" + key2;\r\n\tVeryComplexClass value = cache.get(key);\r\n\r\n\t\/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u306b\u63a2\u3057\u3066\u3044\u308b\u5024\u304c\u3042\u3063\u305f\u306e\u3067\u5373return\u3059\u308b\r\n\tif (value != null) {\r\n\t\treturn value;\r\n\t}\r\n\r\n\t\/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u306b\u63a2\u3057\u3066\u3044\u308b\u5024\u304c\u306a\u304b\u3063\u305f\u306e\u3067\u3001\u751f\u6210\u3057\u3066\u30ad\u30e3\u30c3\u30b7\u30e5\u306bput\u3059\u308b\r\n\tvalue = new VeryComplexClass();\r\n\t\/\/ \u305d\u306e\u4ed6\u3044\u308d\u3044\u308d\u8907\u96d1\u306a\u521d\u671f\u5316\u51e6\u7406\u2026\r\n\tcache.put(key, value);\r\n\treturn value;\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u30ad\u30fc\u3092\u30af\u30e9\u30b9\u3068\u3057\u305f\u5834\u5408\r\nprivate Map&lt;VeryComplexClassKey, VeryComplexClass&gt; cache = new HashMap&lt;&gt;(); \/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u3068\u3057\u3066\u4f7f\u3046Map\u3092\u4f5c\u308b\u3002\u5185\u5bb9\u306f\u521d\u671f\u72b6\u614b\u3067\u306f\u7a7a\u3002\r\n\r\npublic VeryComplexClass getVeryComplexClass(VeryComplexClass key) {\r\n\tVeryComplexClass value = cache.get(key);\r\n\r\n\t\/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u306b\u63a2\u3057\u3066\u3044\u308b\u5024\u304c\u3042\u3063\u305f\u306e\u3067\u5373return\u3059\u308b\r\n\tif (value != null) {\r\n\t\treturn value;\r\n\t}\r\n\r\n\t\/\/ \u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u306b\u63a2\u3057\u3066\u3044\u308b\u5024\u304c\u306a\u304b\u3063\u305f\u306e\u3067\u3001\u751f\u6210\u3057\u3066\u30ad\u30e3\u30c3\u30b7\u30e5\u306bput\u3059\u308b\r\n\tvalue = new VeryComplexClass();\r\n\t\/\/ \u305d\u306e\u4ed6\u3044\u308d\u3044\u308d\u8907\u96d1\u306a\u521d\u671f\u5316\u51e6\u7406\u2026\r\n\tcache.put(key, value);\r\n\treturn value;\r\n}<\/pre>\n<p>\u30ad\u30e3\u30c3\u30b7\u30e5\u7528\u9014\u3067\u306f<span>Set<\/span>\u3082\u9078\u629e\u80a2\u3067\u3059\u304c\u3001<span>Map<\/span>\u3068\u306f\u4f7f\u3044\u9053\u304c\u9055\u3044\u307e\u3059\u3002<span>Set<\/span>\u306e\u6a5f\u80fd\u306f\u5024\u3092\u4e00\u610f\u306b\u3059\u308b\u3053\u3068\u306a\u306e\u3067\u3001\u5024\u3092\u5358\u7d14\u306b\u6e9c\u3081\u3053\u3093\u3067\u3001\u5f8c\u304b\u3089\u307e\u3068\u3081\u3066\u4f55\u304b\u3092\u3059\u308b<span>\u2026<\/span>\u3068\u3044\u3046\u7528\u9014\u306b\u5411\u3044\u3066\u3044\u307e\u3059\u3002<span>Set<\/span>\u306f\u3001<span>String<\/span>\u3084<span>Integer<\/span>\u306a\u3069\u306e\u5358\u7d14\u306a\u5024\u306a\u3089\u3068\u3082\u304b\u304f\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u306e\u691c\u7d22\u306e\u3057\u3084\u3059\u3055\u3067\u306f<span>Map<\/span>\u3088\u308a\u3082\u4e0d\u5229\u306a\u306e\u3067\u3059\u3002<\/p>\n<h3><span id=\"-Map-5\">\uff13-\uff14\uff0e\u3010\u53c2\u8003\u3011<span>Map<\/span>\u3092\u30d5\u30a1\u30a4\u30eb\u3078\u8aad\u307f\u66f8\u304d\u3059\u308b<\/span><\/h3>\n<p>Map\u306e\u30ad\u30fc\u3084\u5024\u3092<span>Serializable<\/span>\u306a\u30af\u30e9\u30b9\u306b\u3057\u3066\u304a\u3051\u3070\u3001<span>ObjectInputStream\/ObjectOutputStream<\/span>\u3092\u4f7f\u3063\u3066\u3001<span>Map(<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9<span>)<\/span>\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u30d5\u30a1\u30a4\u30eb\u3084\u30cd\u30c3\u30c8\u30ef\u30fc\u30af\u7d4c\u7531\u3067\u8aad\u307f\u66f8\u304d\u3067\u304d\u307e\u3059\u3002<span>Map<\/span>\u306e\u30ad\u30fc\u3068\u5024\u3092\u30c6\u30ad\u30b9\u30c8\u30d5\u30a1\u30a4\u30eb\u306a\u3069\u306b\u66f8\u304d\u51fa\u3057\u3066\u518d\u5ea6\u8aad\u307f\u8fbc\u307f\u3001<span>put<\/span>\u3057\u76f4\u3059\u3088\u308a\u3082\u7c21\u5358\u3067\u3059\u3002<\/p>\n<p>\u3053\u308c\u3092\u4f7f\u3046\u30b1\u30fc\u30b9\u306f\u3042\u307e\u308a\u306a\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u3067\u3082\u3001\u3067\u304d\u308b\u3068\u3044\u3046\u3053\u3068\u306f\u982d\u306e\u7247\u9685\u3067\u899a\u3048\u3066\u304a\u304f\u3068\u3001\u4fbf\u5229\u306b\u4f7f\u3048\u308b\u6642\u304c\u3042\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3088<span>?<\/span><\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Map\u3092\u4f5c\u3063\u3066\u2026\r\nMap&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\n\/\/ ObjectOutputStream\u3067\u30d5\u30a1\u30a4\u30eb\u3078Map\u3092\u51fa\u529b\u3057\u3066\u2026\r\ntry (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(\"\/A\/B\/animals.ser\"))) {\r\n\toos.writeObject(map);\r\n}\r\n\r\n\/\/ ObjectInputStream\u3067\u30d5\u30a1\u30a4\u30eb\u304b\u3089Map\u3092\u8aad\u307f\u8fbc\u3080!!\r\ntry (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(\"\/A\/B\/animals.ser\"))) {\r\n\tmap = (Map&lt;String, String&gt;)ois.readObject();\r\n}\r\n\r\nSystem.out.println(map.get(\"\u732b\")); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"!! \u30d5\u30a1\u30a4\u30eb\u306bMap\u306e\u5185\u5bb9\u304c\u4fdd\u5b58\u3067\u304d\u305f!!<\/pre>\n<h2><span id=\"Map-2\">\uff14\uff0e\u3010\u91cd\u8981\u3011<span>Map<\/span>\u3092\u4f7f\u3046\u306e\u306b\u6b20\u304b\u305b\u306a\u3044\u3082\u306e<\/span><\/h2>\n<h3><span id=\"-Objectequals\">\uff14-\uff11\uff0e\u3010\u5fc5\u9808\u3011<span>Object.equals<\/span>\u306f\u30ad\u30fc\u304c\u540c\u3058\u304b\u306e\u5224\u65ad\u306b\u4f7f\u3046<\/span><\/h3>\n<p>Map\u306e\u30ad\u30fc\u306b\u4f7f\u3046\u30af\u30e9\u30b9\u306b\u306f\u3001\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u300c\u540c\u3058\u300d\u304b\u5224\u65ad\u3059\u308b\u30e1\u30bd\u30c3\u30c9<span>Object.equals<\/span>\u304c\u300c\u6b63\u3057\u304f\u300d\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3055\u308c\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002\u3053\u308c\u306f<span>Map<\/span>\u3092\u4f7f\u3046\u4e0a\u3067\u306f\u5fc5\u9808\u3067\u3059\u3002<span>Map<\/span>\u304b\u3089\u306e<span>get<\/span>\u3067\u306f\u3001<span>Map<\/span>\u304c\u6301\u3064\u30ad\u30fc\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e\u4e2d\u304b\u3089\u3001<span>equals<\/span>\u3067\u540c\u3058\u3082\u306e\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u5024\u3092\u5f97\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n<p>Map\u306e\u30ad\u30fc\u306b\u306f\u3042\u306a\u305f\u304c\u4f7f\u3044\u305f\u3044\u30af\u30e9\u30b9\u3092\u4f7f\u3048\u307e\u3059\u3002\u3067\u3082\u3001\u81ea\u5206\u3067\u4f5c\u3063\u305f\u30af\u30e9\u30b9\u3092\u4f7f\u3046\u5834\u5408\u306f\u3001<span>equals<\/span>\u304c\u300c\u6b63\u3057\u304f\u300d\u4f5c\u3089\u308c\u3066\u3044\u308b\u304b\u6c17\u3092\u4ed8\u3051\u307e\u3057\u3087\u3046\u3002\u4e00\u65b9\u3001<span>Java<\/span>\u6a19\u6e96<span>API<\/span>\u306e\u30af\u30e9\u30b9<span>(String<\/span>\u7b49<span>)<\/span>\u306f\u3057\u3063\u304b\u308a\u3068<span>equals<\/span>\u304c\u4f5c\u3089\u308c\u3066\u3044\u307e\u3059\u306e\u3067\u3001\u666e\u901a\u306f\u554f\u984c\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>Object.equals\u306e\u8a73\u7d30\u306f\u3001\u4ee5\u4e0b\u306e\u8a18\u4e8b\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n<span style=\"text-decoration:none !important; background-color:#a61e58; color:white; padding:4px 13px; font-size:12px; font-weight:bold; position:relative; top:10px; z-index:1; left:11px;\">\u95a2\u9023\u8a18\u4e8b<\/span>\n<div class=\"blog-card\"><a target=\"_blank\" href=\"https:\/\/www.bold.ne.jp\/engineer-club\/java-equals\" style=\"text-decoration:none;\">\n    <div class=\"blog-card-thumbnail\"><img src='https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2018\/10\/shutterstock_568617811-600x366.jpg' alt='java equals\u3068\u306f\uff1fjava equals\u3092\u901a\u3058\u3066\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u300c\u540c\u3058\u300d\u304b\u30c1\u30a7\u30c3\u30af\u3057\u3088\u3046' width=160 height=98 \/><\/div>\n    <div class=\"blog-card-content\">\n        <div class=\"blog-card-title\">java equals\u3068\u306f\uff1fjava equals\u3092\u901a\u3058\u3066\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u300c\u540c\u3058\u300d\u304b\u30c1\u30a7\u30c3\u30af\u3057\u3088\u3046 <\/div>\n        <span style=\"font-size: 12px; font-weight: normal; position:relative; color:#666;\"><i class=\"fa fa-clock-o\"><\/i>&nbsp;2025\/10\/06<\/span>\n    <\/div>\n<div class=\"clear\"><\/div>\n<\/a><\/div>\n<h3><span id=\"-ObjecthashCodeMap\">\uff14-\uff12\uff0eObject.hashCode\u306f\u4e00\u90e8\u306e<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3067\u306f\u5fc5\u9808<\/span><\/h3>\n<p>Object.hashCode\u306f\u3001\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3068\u3057\u3066\u306e<span>Map<\/span>\u3092\u4f7f\u3046\u306b\u306f\u5fc5\u9808\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3067\u3082\u3001<span>Map<\/span>\u306e\u7279\u5b9a\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3001\u4f8b\u3048\u3070<span>Java<\/span>\u306e\u6a19\u6e96<span>API<\/span>\u306b\u3042\u308b<span>HashMap<\/span>\u3084<span>LinkedHashMap<\/span>\u306a\u3069\u3092\u4f7f\u3046\u6642\u306b\u306f\u3001\u30ad\u30fc\u306e\u30af\u30e9\u30b9\u306b<span>hashCode<\/span>\u304c\u300c\u6b63\u3057\u304f\u300d\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3055\u308c\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>\u5b9f\u969b\u306e<span>Java<\/span>\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u306f<span>HashMap<\/span>\u304c\u5927\u5909\u3088\u304f\u4f7f\u308f\u308c\u307e\u3059\u3002<span>HashMap<\/span>\u3067\u30ad\u30fc\u3068\u3059\u308b\u30af\u30e9\u30b9\u304c\u81ea\u5206\u3067\u4f5c\u3063\u305f\u3082\u306e\u306a\u3089\u3001<span>hashCode<\/span>\u304c\u300c\u6b63\u3057\u304f\u300d\u4f5c\u3089\u308c\u3066\u3044\u308b\u304b\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002\u305d\u3046\u3057\u306a\u3044\u3068\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u4e0a\u624b\u304f\u52d5\u304b\u306a\u3044\u539f\u56e0\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>Object.hashCode\u306e\u8a73\u7d30\u306f\u3001\u4ee5\u4e0b\u306e\u8a18\u4e8b\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n<span style=\"text-decoration:none !important; background-color:#a61e58; color:white; padding:4px 13px; font-size:12px; font-weight:bold; position:relative; top:10px; z-index:1; left:11px;\">\u95a2\u9023\u8a18\u4e8b<\/span>\n<div class=\"blog-card\"><a target=\"_blank\" href=\"https:\/\/www.bold.ne.jp\/engineer-club\/java-hashcode\" style=\"text-decoration:none;\">\n    <div class=\"blog-card-thumbnail\"><img src='https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2018\/10\/shutterstock_568617811-600x366.jpg' alt='Java\u3092\u9670\u304b\u3089\u652f\u3048\u308bhashCode\u3068\u306f\uff1fhashCode\u306e\u4ed5\u7d44\u307f\u3068\u5b9f\u88c5\u65b9\u6cd5' width=160 height=98 \/><\/div>\n    <div class=\"blog-card-content\">\n        <div class=\"blog-card-title\">Java\u3092\u9670\u304b\u3089\u652f\u3048\u308bhashCode\u3068\u306f\uff1fhashCode\u306e\u4ed5\u7d44\u307f\u3068\u5b9f\u88c5\u65b9\u6cd5 <\/div>\n        <span style=\"font-size: 12px; font-weight: normal; position:relative; color:#666;\"><i class=\"fa fa-clock-o\"><\/i>&nbsp;2025\/10\/06<\/span>\n    <\/div>\n<div class=\"clear\"><\/div>\n<\/a><\/div>\n<h3><span id=\"-Comparable\">\uff14-\uff13\uff0eComparable\u306f\u305c\u3072\u610f\u8b58\u3057\u305f\u3044\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9<\/span><\/h3>\n<p>\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e\u5927\u5c0f\u3092\u6bd4\u8f03\u3059\u308b<span>Comparable<\/span>\u306f\u3001<span>Map<\/span>\u3092\u4f7f\u3046\u4e0a\u3067\u306f\u305c\u3072\u610f\u8b58\u3057\u305f\u3044\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3067\u3059\u3002\u4e00\u90e8\u306e<span>Map<\/span>\u5b9f\u88c5\u30af\u30e9\u30b9\u3092\u4f7f\u3046\u306a\u3089\u5fc5\u9808\u3067\u3059\u3057\u3001\u6027\u80fd\u5411\u4e0a\u306b\u3064\u306a\u304c\u308b\u3053\u3068\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u3001<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3068\u3057\u3066<span>TreeMap<\/span>\u3092\u4f7f\u3046\u306b\u306f\u3001\u30ad\u30fc\u304c<span>Comparable<\/span>\u3067\u3042\u308b\u304b\u3001\u3042\u308b\u3044\u306f<span>Comparator<\/span>\u3092\u4f7f\u3063\u305f\u5927\u5c0f\u6bd4\u8f03\u304c\u51fa\u6765\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002<span>TreeMap<\/span>\u306f\u30ad\u30fc\u306e\u300c\u9806\u756a\u300d\u3092\u610f\u8b58\u3057\u3066\u304f\u308c\u308b<span>Map<\/span>\u3067\u3059\u304c\u3001\u305d\u306e\u305f\u3081\u306b\u306f\u30ad\u30fc\u306e\u5927\u5c0f\u3092\u6bd4\u8f03\u3059\u308b<span>Comparable.compareTo<\/span>\u304b\u3001<span>Comparator<\/span>\u304c\u5fc5\u8981\u306a\u306e\u3067\u3059\u3002<\/p>\n<p>\u305d\u3057\u3066\u3001\u30ad\u30fc\u304c<span>Comparable<\/span>\u3092\u5b9f\u88c5\u3057\u3066\u3044\u3066\u30ad\u30fc\u306e\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b\u3068\u3001\u4e00\u90e8\u306e<span>Map<\/span>\u3067\u306f\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u6027\u80fd\u304c\u3088\u304f\u306a\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001<span>HashMap<\/span>\u3067\u30ad\u30fc\u306e\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b\u3068\u3001\u5927\u91cf\u30c7\u30fc\u30bf\u3092\u6271\u3046\u5834\u5408\u306e\u30c7\u30fc\u30bf\u7ba1\u7406\u3092\u3088\u308a\u52b9\u7387\u7684\u306b\u884c\u3048\u308b\u306e\u3067\u3001<span>put<\/span>\u3059\u308b\u6642\u306a\u3069\u3067\u30ec\u30b9\u30dd\u30f3\u30b9\u304c\u3088\u304f\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>Comparable\u306e\u8a73\u7d30\u306f\u3001\u4ee5\u4e0b\u306e\u8a18\u4e8b\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n<span style=\"text-decoration:none !important; background-color:#a61e58; color:white; padding:4px 13px; font-size:12px; font-weight:bold; position:relative; top:10px; z-index:1; left:11px;\">\u95a2\u9023\u8a18\u4e8b<\/span>\n<div class=\"blog-card\"><a target=\"_blank\" href=\"https:\/\/www.bold.ne.jp\/engineer-club\/java-compareto\" style=\"text-decoration:none;\">\n    <div class=\"blog-card-thumbnail\"><img src='https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2018\/10\/shutterstock_568617811-600x366.jpg' alt='Java\u306ecompareTo\u3068\u306f\uff1f\u30bd\u30fc\u30c8\u3092\u81ea\u7531\u81ea\u5728\u306b\u64cd\u308b\u305f\u3081\u306ecompareTo\u306e\u4f7f\u3044\u65b9' width=160 height=98 \/><\/div>\n    <div class=\"blog-card-content\">\n        <div class=\"blog-card-title\">Java\u306ecompareTo\u3068\u306f\uff1f\u30bd\u30fc\u30c8\u3092\u81ea\u7531\u81ea\u5728\u306b\u64cd\u308b\u305f\u3081\u306ecompareTo\u306e\u4f7f\u3044\u65b9 <\/div>\n        <span style=\"font-size: 12px; font-weight: normal; position:relative; color:#666;\"><i class=\"fa fa-clock-o\"><\/i>&nbsp;2025\/09\/17<\/span>\n    <\/div>\n<div class=\"clear\"><\/div>\n<\/a><\/div>\n<h2><span id=\"MapJava_8\">\uff15\uff0e\u3010\u767a\u5c55\u3011<span>Map<\/span>\u306b<span>Java 8<\/span>\u4ee5\u964d\u3067\u8ffd\u52a0\u3055\u308c\u305f\u6a5f\u80fd<\/span><\/h2>\n<p>Map\u306f<span>Java 8<\/span>\u3067\u591a\u304f\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u8ffd\u52a0\u3055\u308c\u3001\u4ee5\u5f8c\u3082\u6a5f\u80fd\u5f37\u5316\u306f\u7d9a\u3044\u3066\u3044\u307e\u3059\u3002\u3044\u307e\u307e\u3067\u81ea\u5206\u3067\u66f8\u3044\u3066\u3044\u305f\u51e6\u7406\u3092\u80a9\u4ee3\u308f\u308a\u3057\u3066\u304f\u308c\u308b\u3082\u306e\u3082\u591a\u3044\u306e\u3067\u3001\u305c\u3072\u6d3b\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u3053\u3053\u3067\u306f\u3001<span>Java 8<\/span>\u4ee5\u964d\u3067\u8ffd\u52a0\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u306e\u4e2d\u3067\u300c\u3053\u308c\u306f<span>!!<\/span>\u300d\u3068\u3044\u3046\u3082\u306e\u306e\u4f7f\u3044\u65b9\u3092\u304a\u4f1d\u3048\u3057\u307e\u3059<span>(Java 11<\/span>\u6642\u70b9<span>)<\/span>\u3002\u306a\u304a\u3001\u4ee5\u4e0b\u3067\u8a73\u7d30\u3092\u7d39\u4ecb\u3057\u3066\u3044\u306a\u3044\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u7c21\u5358\u306b\u307e\u3068\u3081\u308b\u3068\u3001\u4ee5\u4e0b\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<blockquote>\n<p>getOrDefault\uff1a<span>get<\/span>\u3059\u308b\u969b\u306b\u3001\u30ad\u30fc\u306e\u5bfe\u5fdc\u4ed8\u3051\u304c\u306a\u3044\u6642\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u6307\u5b9a\u3067\u304d\u308b<\/p>\n<p>forEach\uff1a\u4fdd\u6301\u3059\u308b\u30ad\u30fc\u30fb\u5024\u306e\u5bfe\u5fdc\u3067\u30eb\u30fc\u30d7\u3059\u308b\u3002<span>entrySet\u2192<\/span>\u30eb\u30fc\u30d7\u3092\u66f8\u304b\u306a\u304f\u3066\u3044\u3044\u305f\u3081\u304a\u624b\u8efd\u3002<\/p>\n<p>replaceAll\uff1a\u5024\u5168\u4f53\u3092\u51e6\u7406\u7d50\u679c\u3067\u4e00\u62ec\u7f6e\u63db\u3059\u308b<\/p>\n<p>remove(\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u7248<span>)<\/span>\uff1a\u30ad\u30fc\u3068\u5024\u304c\u4e00\u81f4\u3059\u308b\u5834\u5408\u306e\u307f\u524a\u9664\u3059\u308b<\/p>\n<p>ofEntries\uff1a<span>Map<\/span>\u304c\u65e2\u306b\u6301\u3063\u3066\u3044\u308b\u3001\u7279\u5b9a\u306e\u8907\u6570\u30a8\u30f3\u30c8\u30ea\u306e\u307f\u6301\u3063\u305f\u8aad\u307f\u53d6\u308a\u5c02\u7528\u306e<span>Map<\/span>\u3092\u7c21\u5358\u306b\u4f5c\u308b<\/p>\n<p>entry\uff1a<span>Map<\/span>\u304c\u65e2\u306b\u6301\u3063\u3066\u3044\u308b\u3001\u7279\u5b9a\u306e\u30ad\u30fc\u3068\u5024\u3060\u3051\u6301\u3064\u8aad\u307f\u53d6\u308a\u5c02\u7528\u306e<span>Map<\/span>\u3092\u4f5c\u308b<\/p>\n<\/blockquote>\n<p>\u306a\u304a\u3001<span>Java 8<\/span>\u3067\u8ffd\u52a0\u3055\u308c\u305f\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3092\u4f7f\u3046\u30e1\u30bd\u30c3\u30c9\u304c\u591a\u3044\u306e\u3067\u3001\u6d3b\u7528\u3057\u305f\u3044\u5834\u5408\u306f\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3084\u30e9\u30e0\u30c0\u5f0f\u3092\u52c9\u5f37\u3057\u3066\u304a\u304f\u3068\u3088\u3044\u3067\u3057\u3087\u3046\u3002\u6700\u521d\u306f\u6b63\u76f4\u8a00\u3063\u3066\u3068\u3063\u3064\u304d\u3065\u3089\u3044\u3067\u3059\u304c\u3001\u6163\u308c\u3066\u304f\u308b\u3068\u305d\u308c\u3089\u306a\u3057\u3067\u306f\u3044\u3089\u308c\u306a\u304f\u306a\u308a\u307e\u3059\u3088\u3002<\/p>\n<h3><span id=\"-putIfAbsentJava_8\">\uff15-\uff11\uff0eputIfAbsent\u3067\u3001\u5bfe\u5fdc\u4ed8\u3051\u304c\u306a\u3044\u6642\u306e\u5024\u3092\u6307\u5b9a\u3059\u308b\u3010<span>Java 8<\/span>\uff5e\u3011<\/span><\/h3>\n<p>absent\u306f\u300c\u306a\u3044\u300d\u3068\u3044\u3046\u610f\u5473\u306e\u5358\u8a9e\u3067\u3059\u3002\u30e1\u30bd\u30c3\u30c9\u540d\u3092\u7d20\u76f4\u306b\u8aad\u3080\u3068\u300c\u306a\u3044\u306a\u3089<span>put<\/span>\u3059\u308b\u300d\u3067\u3001\u5b9f\u969b\u306e\u52d5\u304d\u3082\u30ad\u30fc\u304c\u306a\u3044\u5834\u5408\u306b\u3060\u3051<span>put<\/span>\u3059\u308b\u3082\u306e\u3067\u3059\u3002\u623b\u308a\u5024\u306f\u3001\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u7d42\u308f\u3063\u305f\u6642\u70b9\u3067\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u3066\u3044\u308b\u5024\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\ndefault V putIfAbsent(K key, V value)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u6307\u5b9a\u3055\u308c\u305f\u5024\u304c\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u30ad\u30fc\r\n\tvalue - \u6307\u5b9a\u3055\u308c\u305f\u9375\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u5024\r\n\u623b\u308a\u5024:\r\n\t\u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u305f\u4ee5\u524d\u306e\u5024\u3002\u30ad\u30fc\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u304c\u306a\u304b\u3063\u305f\u5834\u5408\u306fnull\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nmap.putIfAbsent(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\nmap.putIfAbsent(\"\u72f8\", \"\u307d\u3053\u306b\u3083\u3093\");\r\n\r\nSystem.out.println(map.get(\"\u732b\")); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\u3001\u65e2\u306b\u30ad\u30fc\"\u732b\"\u304c\u3042\u3063\u305f\u306e\u3067\u3001put\u3055\u308c\u306a\u304b\u3063\u305f\r\nSystem.out.println(map.get(\"\u72f8\")); \/\/ \u2192 \"\u307d\u3053\u306b\u3083\u3093\"<\/pre>\n<p>putIfAbsent\u306f\u3001\u5f93\u6765\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3057\u3066\u3044\u305f\u51e6\u7406\u306e\u4ee3\u308f\u308a\u306b\u306a\u308a\u307e\u3059\u3002<span>if<\/span>\u6587\u3067\u5224\u65ad\u3057\u306a\u304f\u3066\u3082\u3044\u3044\u306e\u3067\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u77ed\u304f\u306a\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">String value = map.get(\"\u732b\");\r\nif (value == null) {\r\n\tvalue = map.put(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\n}\r\nreturn value;<\/pre>\n<h3><span id=\"-replaceJava_8\">\uff15-\uff12\uff0ereplace\u3067\u30ad\u30fc\u304c\u3042\u308b\u306a\u3089\u5024\u3092\u5165\u308c\u66ff\u3048\u308b\u3010<span>Java 8<\/span>\uff5e\u3011<\/span><\/h3>\n<p>replace\u306f\u3001\u5f15\u6570\u306e\u30ad\u30fc\u304c<span>Map<\/span>\u306b\u3042\u308c\u3070\u5024\u3092\u5165\u308c\u66ff\u3048\u3001\u30ad\u30fc\u304c\u306a\u3051\u308c\u3070\u4f55\u3082\u3057\u307e\u305b\u3093\u3002\u623b\u308a\u5024\u306f\u5165\u308c\u66ff\u3048\u304c\u3055\u308c\u305f\u304b\u3069\u3046\u304b\u306e<span>boolean<\/span>\u3067\u3001\u5165\u308c\u66ff\u3048\u3055\u308c\u305f\u3089<span>true<\/span>\u3001\u3055\u308c\u306a\u304b\u3063\u305f\u3089<span>false<\/span>\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\ndefault boolean replace(K key, V oldValue, V newValue)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u6307\u5b9a\u3055\u308c\u305f\u5024\u304c\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u30ad\u30fc\r\n\toldValue - \u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u3066\u3044\u308b\u3068\u4e88\u60f3\u3055\u308c\u308b\u5024\r\n\tnewValue - \u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u5024\r\n\u623b\u308a\u5024:\r\n\t\u5024\u304c\u7f6e\u63db\u3055\u308c\u305f\u5834\u5408\u306ftrue<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nmap.replace(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\nmap.replace(\"\u72f8\", \"\u307d\u3053\u306b\u3083\u3093\");\r\n\r\nSystem.out.println(map.get(\"\u732b\")); \/\/ \u2192 \"\u30cb\u30e3\u30b8\u30e9\"\r\nSystem.out.println(map.get(\"\u72f8\")); \/\/ \u2192 null<\/pre>\n<p>replace\u306f\u3001\u5f93\u6765\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3057\u3066\u3044\u305f\u7b87\u6240\u306e\u4ee3\u308f\u308a\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">if (map.containsKey(\"\u732b\")) {\r\n\treturn map.put(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\n} else {\r\n\treturn null;\r\n}<\/pre>\n<h3><span id=\"-computemergeJava_8\">\uff15-\uff13\uff0ecompute\/merge\u3067\u5024\u306e\u52a0\u5de5\u3092\u3059\u308b\u3010<span>Java 8<\/span>\uff5e\u3011<\/span><\/h3>\n<p>Map\u306e\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u305f\u5024\u3092\u52a0\u5de5\u30fb\u7de8\u96c6\u3057\u3066\u5165\u308c\u66ff\u3048\u305f\u3044\u3053\u3068\u306f\u826f\u304f\u3042\u308a\u307e\u3059\u3002<span>Map<\/span>\u306e\u6d3b\u7528\u4f8b\u3067\u6319\u3052\u305f\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u306f\u305d\u306e\u5178\u578b\u4f8b\u3067\u3059\u3002\u305d\u306e\u7528\u9014\u306b\u306f\u3001<span>Java 8<\/span>\u4ee5\u964d\u306a\u3089<span>compute<\/span>\u3084\u95a2\u9023\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3063\u3066\u307f\u307e\u3057\u3087\u3046\u3002<span>if<\/span>\u6587\u306e\u30d6\u30ed\u30c3\u30af\u304c\u5c11\u306a\u304f\u306a\u3063\u3066\u3001\u30b9\u30c3\u30ad\u30ea\u3057\u307e\u3059\u3088\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\ndefault V compute(K key, BiFunction&lt;? super K,? super V,? extends V&gt; remappingFunction)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tkey - \u6307\u5b9a\u3055\u308c\u305f\u5024\u304c\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u30ad\u30fc\r\n\tremappingFunction - \u5024\u3092\u30b3\u30f3\u30d4\u30e5\u30fc\u30c8\u3059\u308b\u305f\u3081\u306e\u518d\u30de\u30c3\u30d7\u95a2\u6570\r\n\u623b\u308a\u5024:\r\n\t\u6307\u5b9a\u3055\u308c\u305f\u30ad\u30fc\u306b\u95a2\u9023\u4ed8\u3051\u3089\u308c\u308b\u65b0\u3057\u3044\u5024\u3002\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306fnull<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">List&lt;String&gt; data = Arrays.asList(\"A,100\", \"B,50\", \"C,200\", \"A,150\", \"B,1000\"); \/\/ \u30ad\u30fc\u6587\u5b57\u5217\u3001\u5024\u3092\u6301\u3063\u305f\u30c7\u30fc\u30bf\r\nMap&lt;String, Integer&gt; groupBy = new HashMap&lt;&gt;(); \/\/ \u30ad\u30fc\u306fString\u3001\u5024\u306f\u6570\u5b57\u306e\u96c6\u8a08\u5024\r\n\r\nfor (String d : data) {\r\n\tString[] items = d.split(\",\");\r\n\tInteger num = Integer.valueOf(items[1]);\r\n\r\n\tgroupBy.compute(items[0], (k, v) -&gt; v == null ? num : v + num);\r\n}\r\n\r\nSystem.out.println(groupBy.get(\"A\")); \/\/ \u2192 250<\/pre>\n<p>compute\u306e\u5f15\u6570\u306f\u3001\u30ad\u30fc\u3068\u3001\u5024\u3092\u7de8\u96c6\u3059\u308b<span>BiFunction<\/span>\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3067\u3059\u3002<span>BiFunction.apply<\/span>\u3078\u306e\u5f15\u6570\u306f\u30ad\u30fc\u3068\u305d\u306e\u6642\u70b9\u3067\u306e\u5024\u304c\u6e21\u3055\u308c\u3001\u623b\u308a\u5024\u306f\u30ad\u30fc\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u308b\u66f4\u65b0\u5f8c\u306e\u5024\u3067\u3059\u3002\u3053\u306e\u4f8b\u3067\u306f\u3001<span>Map<\/span>\u306b\u30ad\u30fc\u304c\u306a\u3051\u308c\u3070\u6570\u5024\u3092\u65b0\u305f\u306b\u5bfe\u5fdc\u4ed8\u3051\u3066\u3001\u3042\u308c\u3070\u65e2\u5b58\u306e\u5024\u306b\u65b0\u3057\u3044\u6570\u5024\u3092\u8db3\u3057\u3053\u3093\u3067\u3044\u307e\u3059\u3002<\/p>\n<p>\u306a\u304a\u3001computeIfAbsent\/computeIfPresent\/merge\u3082\u4f3c\u305f\u3088\u3046\u306a\u51e6\u7406\u3092\u884c\u3044\u307e\u3059(merge\u306e\u307fJava 10\uff5e)\u3002\u9055\u3046\u306e\u306f\u3001\u30ad\u30fc\u304c\u3042\u308b\u30fb\u306a\u3044\u306a\u3069\u306e\u72b6\u6cc1\u306b\u5408\u308f\u305b\u305f\u3001BiFunction\u306e\u547c\u3070\u308c\u65b9\u3067\u3059\u3002\u5927\u307e\u304b\u306b\u307e\u3068\u3081\u308b\u3068\u4ee5\u4e0b\u306e\u3068\u304a\u308a\u3067\u3059\u304c\u3001\u8a73\u7d30\u306f<span>Javadoc<\/span>\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<blockquote>\n<p>computeIfAbsent\uff1a<span>Map<\/span>\u306b\u30ad\u30fc\u304c\u306a\u3044\u3001\u3042\u308b\u3044\u306f\u30ad\u30fc\u306f\u3042\u308b\u304c\u5024\u304c<span>null<\/span>\u306e\u5834\u5408\u306b\u3001<span>BiFunction.apply<\/span>\u304c\u5b9f\u884c\u3055\u308c\u308b<\/p>\n<p>computeIfPresent\uff1aMap\u306b\u30ad\u30fc\u304c\u3042\u308a\u5024\u304cnull\u3067\u306a\u3044\u5834\u5408\u306b\u3001BiFunction.apply\u304c\u5b9f\u884c\u3055\u308c\u308b<\/p>\n<p>merge\uff1acomputeIfAbsent\u3068\u540c\u3058\u52d5\u304d\u3002\u305f\u3060\u3057\u3001<span>BiFunction.apply<\/span>\u306e\u623b\u308a\u5024\u304c<span>null<\/span>\u306a\u3089\u30ad\u30fc\u304c<span>remove<\/span>\u3055\u308c\u308b<\/p>\n<\/blockquote>\n<h3><span id=\"-ofcopyOfMap\">\uff15-\uff14\uff0eof\/copyOf\u3067\u5909\u66f4\u3067\u304d\u306a\u3044<span>Map<\/span>\u3092\u7c21\u5358\u306b\u4f5c\u308b<\/span><\/h3>\n<h4>\uff15-\uff14-\uff11\uff0eof\u3067\u5909\u66f4\u3067\u304d\u306a\u3044<span>Map<\/span>\u3092\u4f5c\u308b\u3010<span>Java 9<\/span>\uff5e\u3011<\/h4>\n<p>Map\u3092\u4f7f\u3046\u6642\u306f\u3001\u666e\u901a\u306f<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u3092<span>new<\/span>\u3057\u3066<span>put<\/span>\u3092\u3057\u307e\u3059\u3002\u3067\u3059\u304c\u3001<span>Map<\/span>\u304c\u5909\u66f4\u3067\u304d\u306a\u304f\u3066\u3082\u3088\u3051\u308c\u3070\u3001<span>Map.of<\/span>\u3092\u4f7f\u3063\u3066\u7c21\u5358\u306b<span>Map<\/span>\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u4f5c\u308c\u307e\u3059\u3002\u3053\u306e<span>Map<\/span>\u3078<span>put<\/span>\u3084<span>remove<\/span>\u3001<span>clear<\/span>\u306a\u3069\u306e<span>Map<\/span>\u306e\u5185\u5bb9\u3092\u5909\u3048\u308b\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3059\u3068\u3001<span>UnsupportedOperationException<\/span>\u304c<span>throw<\/span>\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nstatic &lt;K,V&gt; Map&lt;K,V&gt; of(K k1, V v1)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tk1 - \u30de\u30c3\u30d4\u30f3\u30b0\u30fb\u30ad\u30fc\r\n\tv1 - \u30de\u30c3\u30d4\u30f3\u30b0\u5024\r\n\u623b\u308a\u5024:\r\n\t\u6307\u5b9a\u3055\u308c\u305f\u30de\u30c3\u30d4\u30f3\u30b0\u3092\u542b\u3080Map<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = Map.of(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\", \"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\nmap.put(\"\u72f8\", \"\u307d\u3053\u306b\u3083\u3093\"); \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306f\u306a\u3089\u306a\u3044\u304c\u3001\u5b9f\u884c\u3059\u308b\u3068UnsupportedOperationException\u304cthrow\u3055\u308c\u308b<\/pre>\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001<span>2<\/span>\u3064\u306e\u30ad\u30fc\u3068\u5024\u3092\u5bfe\u5fdc\u3055\u305b\u305f<span>Map<\/span>\u3092\u4f5c\u308a\u307e\u3057\u305f\u3002<span>of<\/span>\u306b\u306f\u3001<span>0<\/span>\uff5e<span>10<\/span>\u500b\u307e\u3067\u306e\u30ad\u30fc\u3068\u5024\u3092\u4e00\u5ea6\u306b\u5bfe\u5fdc\u3055\u305b\u308b\u305f\u3081\u306e\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308a\u307e\u3059\u306e\u3067\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u4f7f\u3044\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = Map.of(\r\n\t\"K1\", \"V1\", \"K2\", \"V2\", \"K3\", \"V3\", \"K4\", \"V4\", \"K5\", \"V5\",\r\n\t\"K6\", \"V6\", \"K7\", \"V7\", \"K8\", \"V8\", \"K9\", \"V9\", \"K10\", \"V10\");<\/pre>\n<h4>\uff15-\uff14-\uff12\uff0ecopyOf\u3067<span>Map<\/span>\u306e\u30b9\u30ca\u30c3\u30d7\u30b7\u30e7\u30c3\u30c8\u3092\u4f5c\u308b\u3010<span>Java 10<\/span>\uff5e\u3011<\/h4>\n<p>Map.copyOf\u3092\u4f7f\u3046\u3068\u3001\u5f15\u6570\u306e<span>Map<\/span>\u304c\u8aad\u307f\u53d6\u308a\u5c02\u7528<span>(<\/span>\u4e0d\u5909<span>)<\/span>\u306b\u306a\u3063\u305f<span>Map<\/span>\u304c\u623b\u308a\u307e\u3059\u3002<span>of<\/span>\u3068\u540c\u69d8\u306b\u3001<span>copyOf<\/span>\u3067\u4f5c\u3063\u305f<span>Map<\/span>\u306b\u5909\u66f4\u64cd\u4f5c\u3092\u884c\u304a\u3046\u3068\u3059\u308b\u3068\u3001<span>UnsupportedOperationException<\/span>\u304c<span>throw<\/span>\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Java 11\u306e\u65e5\u672c\u8a9e\u7248Javadoc\u3088\u308a\u629c\u7c8b\r\nstatic &lt;K,V&gt; Map&lt;K,V&gt; copyOf(Map&lt;? extends K,? extends V&gt; map)\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\tmap - \u30a8\u30f3\u30c8\u30ea\u304c\u63cf\u753b\u3055\u308c\u308bMap\u306fnull\u3067\u306a\u304f\u3066\u306f\u306a\u308a\u307e\u305b\u3093\r\n\u623b\u308a\u5024:\r\n\t\u4e0e\u3048\u3089\u308c\u305fMap\u306e\u30a8\u30f3\u30c8\u30ea\u3092\u542b\u3080Map<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\n\/\/ Map.copyOf\u3067\u3053\u306e\u6642\u70b9\u3067\u306e\u30b9\u30ca\u30c3\u30d7\u30b7\u30e7\u30c3\u30c8\u3092\u4f5c\u308b\r\nMap&lt;String, String&gt; map2 = Map.copyOf(map);\r\n\r\n\/\/ \u305d\u306e\u3042\u3068\u306b\u3001\u5143\u306eMap\u306e\u5024\u3092\u5909\u66f4+\u30ad\u30fc\u3092\u8ffd\u52a0\u3059\u308b\r\nmap.put(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\nmap.put(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\", \"\u30de\u30a4\u30b1\u30eb\");\r\n\r\nSystem.out.println(map2.get(\"\u732b\")); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\u3001copyOf\u306e\u6642\u306e\u5024\u306e\u307e\u307e\r\nSystem.out.println(map2.get(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\")); \/\/ \u2192 null\u3001copyOf\u3057\u305f\u6642\u306b\u306f\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\"\u306fMap\u306b\u30ad\u30fc\u3068\u3057\u3066\u306a\u3044\u305f\u3081\r\nmap2.put(\"\u72f8\", \"\u307d\u3053\u306b\u3083\u3093\"); \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306f\u306a\u3089\u306a\u3044\u304c\u3001\u5b9f\u884c\u3059\u308b\u3068UnsupportedOperationException\u304cthrow\u3055\u308c\u308b<\/pre>\n<p>\u306a\u304a\u3001\u4e0d\u5909\u306eMap\u3092\u4f5c\u308b\u306b\u306f\u3001Collections.unmodifiableMap\u3082\u3042\u308a\u307e\u3059\u3002\u9055\u3044\u306f\u3001\u4e0d\u5909\u306e<span>Map<\/span>\u306e\u5143\u306b\u306a\u3063\u305f<span>Map<\/span>\u306e\u5909\u66f4\u304c\u53cd\u6620\u3055\u308c\u308b\u304b\u3067\u3059\u3002\u5143\u306e<span>Map<\/span>\u3078\u306e\u5909\u66f4\u304c\u3001<span>Collections.unmodifiableMap<\/span>\u306f\u53cd\u6620\u3055\u308c\u3001<span>Map.copyOf<\/span>\u306f\u53cd\u6620\u3055\u308c\u307e\u305b\u3093\u3002\u3067\u3059\u304b\u3089\u3001<span>Map.copyOf<\/span>\u306f<span>Map<\/span>\u306e\u30b9\u30ca\u30c3\u30d7\u30b7\u30e7\u30c3\u30c8\u3092\u4f5c\u3063\u3066\u3044\u308b\u3068\u3082\u8a00\u3048\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\n\/\/ Collections.unmodifiableMap\u3067\u4e0d\u5909\u306aMap\u3092\u4f5c\u308b\r\nMap&lt;String, String&gt; map2 = Collections.unmodifiableMap(map);\r\n\r\n\/\/ \u305d\u306e\u3042\u3068\u306b\u3001\u5143\u306eMap\u306e\u5024\u3092\u5909\u66f4+\u30ad\u30fc\u3092\u8ffd\u52a0\u3059\u308b\r\nmap.put(\"\u732b\", \"\u30cb\u30e3\u30b8\u30e9\");\r\nmap.put(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\", \"\u30de\u30a4\u30b1\u30eb\");\r\n\r\nSystem.out.println(map2.get(\"\u732b\")); \/\/ \u2192 \"\u30cb\u30e3\u30b8\u30e9\"\r\nSystem.out.println(map2.get(\"\u30dd\u30c3\u30d7\u30b9\u306e\u5e1d\u738b\")); \/\/ \u2192 \"\u30de\u30a4\u30b1\u30eb\"\u3001unmodifiableMap\u5f8c\u3067\u3082Map\u306e\u5185\u5bb9\u306f\u9023\u52d5\u3059\u308b\r\nmap2.put(\"\u72f8\", \"\u307d\u3053\u306b\u3083\u3093\"); \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306f\u306a\u3089\u306a\u3044\u304c\u3001\u5b9f\u884c\u3059\u308b\u3068UnsupportedOperationException\u304cthrow\u3055\u308c\u308b<\/pre>\n<h2><span id=\"Map-3\">\uff16\uff0e\u3010\u767a\u5c55\u3011<span>Map<\/span>\u306b\u307e\u3064\u308f\u308b\u3042\u308c\u3053\u308c<\/span><\/h2>\n<h3><span id=\"-MapJavaAPI\">\uff16-\uff11\uff0eMap\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u7279\u5fb4<span>(Java<\/span>\u6a19\u6e96<span>API)<\/span><\/span><\/h3>\n<p>\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u826f\u304f\u4f7f\u3046\u3001<span>Java<\/span>\u6a19\u6e96<span>API<\/span>\u306e<span>Map<\/span>\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u7279\u5fb4\u3092\u4e00\u89a7\u306b\u3057\u3066\u307f\u307e\u3059\u3002\u826f\u304f\u4f7f\u3046\u306e\u306f<span>HashMap<\/span>\u3068<span>TreeMap<\/span>\u3067\u3059\u3002\u305d\u306e\u4ed6\u306e<span>Map<\/span>\u3084\u3001\u3053\u3053\u306b\u306f\u8a18\u8f09\u3057\u306a\u304b\u3063\u305f<span>Map<\/span>\u306b\u3082\u3001\u305d\u308c\u305e\u308c\u4f7f\u3044\u3069\u3053\u308d\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<table border=\"1\" style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr style=\"height: 48px;\">\n<td style=\"width: 25%; height: 48px; border-color: #000000;\">\u30af\u30e9\u30b9\u540d<\/td>\n<td style=\"width: 25%; height: 48px; border-color: #000000;\">Map\u306e\u7279\u5fb4<\/td>\n<td style=\"width: 25%; height: 48px; border-color: #000000;\">\u30ad\u30fc\u304c\u6301\u3064\u3079\u304d\u7279\u6027<\/td>\n<td style=\"width: 25%; height: 48px; border-color: #000000;\">\u30ad\u30fc\/\u5024\u306bnull\u304c\u53ef\u80fd\u304b<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">HashMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u6700\u3082\u30b9\u30bf\u30f3\u30c0\u30fc\u30c9\u306a<span>Map<\/span>\u3002<span>hashCode<\/span>\u306b\u3088\u308b\u30ad\u30fc\u306e\u7ba1\u7406\u304c\u884c\u308f\u308c\u308b\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">equals + hashCode<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u53ef<br \/>\nnull\u5024=\u53ef<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">LinkedHashMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u30ad\u30fc\u306e\u8ffd\u52a0\u9806\u756a\u3092\u899a\u3048\u3066\u3044\u308b<span>Map<\/span>\u3002\u4f8b\u3048\u3070<span>keySet<\/span>\u3067<span>forEach<\/span>\u3059\u308b\u3068\u3001\u30ad\u30fc\u306e\u8ffd\u52a0\u9806\u756a\u3067\u53d6\u308a\u51fa\u305b\u308b\u3002\u899a\u3048\u308b\u9806\u756a\u306f\u3001\u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u3067\u306e\u6307\u5b9a\u6b21\u7b2c\u3067<span>LRU(Least Recently Used)<\/span>\u306b\u3082\u3067\u304d\u308b\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">equals + hashCode<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u53ef<br \/>\nnull\u5024=\u53ef<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">TreeMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u30ad\u30fc\u3092\u30bd\u30fc\u30c8\u3057\u3066\u7ba1\u7406\u3059\u308b<span>Map<\/span>\u3002\u4f8b\u3048\u3070<span>keySet<\/span>\u3067\u53d6\u5f97\u3057\u305f<span>Set<\/span>\u3067<span>forEach<\/span>\u3059\u308b\u3068\u3001\u30bd\u30fc\u30c8\u6e08\u307f\u306e\u7d50\u679c\u3067\u30ad\u30fc\u304c\u53d6\u308a\u51fa\u305b\u308b\u3002\u30ad\u30fc\u304c<span>Comparable<\/span>\u3067\u3042\u308b\u304b\u3001\u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u3067<span>Comparator<\/span>\u3092\u4e0e\u3048\u308b\u5fc5\u8981\u3042\u308a\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">equals + Comparable<br \/>\n\u203bTreeMap\u306b<span>Comparator<\/span>\u3092\u4e0e\u3048\u308c\u3070\u3001\u30ad\u30fc\u306f<span>Comparable<\/span>\u3067\u306a\u304f\u3066\u3082\u3044\u3044<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u4e0d\u53ef<br \/>\n(\u203b\u30ad\u30fc\u304c<span>Comparable<\/span>\u306e\u5834\u5408\u3002Comparator\u306e\u5b9f\u88c5\u65b9\u6cd5\u306b\u3088\u308a<span>null<\/span>\u3067\u3082\u53ef\u3068\u306a\u308b)<br \/>\nnull\u5024=\u53ef<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">EnumMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u30ad\u30fc\u3068\u3057\u3066<span>Enum<\/span>\u306e\u307f\u4f7f\u3048\u308b\u7279\u6b8a\u306a<span>Map<\/span>\u3002\u52d5\u4f5c\u306f\u3068\u3066\u3082\u9ad8\u901f\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">Enum\u306e\u307f\u30ad\u30fc\u306b\u4f7f\u3048\u308b<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u4e0d\u53ef<br \/>\nnull\u5024=\u53ef<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">WeakHashMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u5f31\u53c2\u7167\u3067\u30ad\u30fc\u3092\u6301\u3064<span>Map<\/span>\u3002\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u6642\u306b\u3001<span>Map<\/span>\u306e\u5916\u3067\u5f37\u53c2\u7167\u3055\u308c\u3066\u3044\u306a\u3044\u30ad\u30fc\u304c\u81ea\u52d5\u3067<span>remove<\/span>\u3055\u308c\u308b\u3002<span>OutOfMemoryError<\/span>\u5bfe\u7b56\u3084\u30ad\u30e3\u30c3\u30b7\u30e5\u7528\u3068\u3057\u3066\u6709\u52b9\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">equals + hashCode<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u53ef<br \/>\nnull\u5024=\u53ef<\/td>\n<\/tr>\n<tr style=\"height: 24px;\">\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">ConcurrentHashMap<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">\u4e26\u5217\u5b9f\u884c\u306b\u5bfe\u5fdc\u3057\u305f<span>HashMap<\/span>\u3002\u8907\u6570\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u306e\u540c\u6642\u30a2\u30af\u30bb\u30b9\u304c\u3042\u3063\u3066\u3082\u3001\u4fdd\u6301\u5185\u5bb9\u306e\u6574\u5408\u6027\u304c\u4fdd\u305f\u308c\u308b\u3002<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">equals + hashCode<\/td>\n<td style=\"width: 25%; height: 24px; border-color: #000000;\">null\u30ad\u30fc=\u4e0d\u53ef<br \/>\nnull\u5024=\u4e0d\u53ef<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3><span id=\"-Map-6\">\uff16-\uff12\uff0eMap\u306e\u30ad\u30fc\u3068\u5024\u3092\u578b\u5f15\u6570\u3067\u7d5e\u308a\u8fbc\u3093\u3067\u3001\u5206\u304b\u308a\u3084\u3059\u304f\u3059\u308b<\/span><\/h3>\n<p>\u524d\u8ff0\u3057\u305f\u3068\u304a\u308a\u3001\u4e0a\u624b\u306a<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u306f\u3001<span>Map<\/span>\u304c\u30ad\u30fc\u3084\u5024\u3068\u3057\u3066\u6271\u3048\u308b\u30af\u30e9\u30b9\u3092\u578b\u5f15\u6570\u3092\u4f7f\u3063\u3066\u7d5e\u308a\u8fbc\u307f\u3001<span>Map<\/span>\u3078\u30d7\u30ed\u30b0\u30e9\u30de\u304c\u6307\u5b9a\u3057\u305f\u30ad\u30fc\u30fb\u5024\u4ee5\u5916\u306e\u30af\u30e9\u30b9\u3092<span>put<\/span>\u3067\u304d\u306a\u304f\u3059\u308b\u3053\u3068\u3067\u3059\u3002<\/p>\n<p>\u30ad\u30fc\u3092\u5236\u9650\u3057\u3066\u3044\u308b\u3044\u3044\u4f8b\u304c<span>EnumMap<\/span>\u3067\u3059\u3002<span>Object<\/span>\u3084<span>String<\/span>\u3067\u306f\u30ad\u30fc\u3068\u3057\u3066\u4f7f\u3048\u308b\u300c\u7bc4\u56f2\u300d\u304c\u5e83\u3059\u304e\u308b\u306e\u3067\u3001<span>Enum<\/span>\u306e\u5024\u3092\u30ad\u30fc\u306b\u3059\u308b\u3053\u3068\u3067\u3001\u30ad\u30fc\u3068\u3057\u3066\u4f7f\u3048\u308b\u3082\u306e\u3092\u660e\u78ba\u306b\u5236\u9650\u3067\u304d\u3066\u3044\u307e\u3059\u3057\u3001\u7528\u9014\u3082\u660e\u78ba\u3067\u3059\u3002\u307e\u305f\u3001<span>Enum<\/span>\u306f\u5b58\u5728\u3059\u308b\u5024\u304c\u56fa\u5b9a\u306a\u306e\u3067\u3001\u51e6\u7406\u306e\u9ad8\u901f\u3055\u306b\u3082\u7e4b\u304c\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>Java 1.4\u4ee5\u524d\u306f<span>Java<\/span>\u306b\u306f\u578b\u5f15\u6570\u306e\u4ed5\u7d44\u307f\u304c\u306a\u304f\u3001<span>Map<\/span>\u306f\u30ad\u30fc\u3082\u5024\u3082\u30e1\u30bd\u30c3\u30c9\u5ba3\u8a00\u4e0a\u306f<span>Object<\/span>\u3067\u3057\u305f\u3002\u3057\u304b\u3082\u60aa\u3044\u3053\u3068\u306b\u3001<span>Map<\/span>\u3067\u3069\u3093\u306a\u30af\u30e9\u30b9\u304c\u30ad\u30fc\u3084\u5024\u306b\u4f7f\u308f\u308c\u3066\u3044\u308b\u304b\u30d7\u30ed\u30b0\u30e9\u30de\u304c\u78ba\u5b9f\u306b\u77e5\u308b\u65b9\u6cd5\u304c\u3042\u308a\u307e\u305b\u3093\u3067\u3057\u305f\u3002<span>Javadoc<\/span>\u3084\u30d7\u30ed\u30b0\u30e9\u30e0\u4e2d\u306e\u30b3\u30e1\u30f3\u30c8\u306b\u66f8\u304f\u306e\u304c\u305b\u3044\u305c\u3044\u3068\u3044\u3046\u3001\u4eca\u3067\u306f\u4fe1\u3058\u3089\u308c\u306a\u3044\u72b6\u614b\u3067\u3059\u3002<\/p>\n<p>\u3067\u3059\u304b\u3089\u3001\u5024\u3092<span>get<\/span>\u3059\u308b\u6642\u306f\u30ad\u30e3\u30b9\u30c8\u304c\u5fc5\u8981\u3067\u3001\u3057\u304b\u3082<span>Map<\/span>\u306b\u4f55\u304c\u5165\u3063\u3066\u3044\u308b\u304b\u5206\u304b\u3089\u306a\u3044\u306e\u3067\u3001<span>ClassCastException<\/span>\u304c\u3088\u304f\u767a\u751f\u3057\u307e\u3057\u305f\u3002\u305d\u308c\u3092\u9632\u3050\u305f\u3081\u306e<span>instanceof<\/span>\u304c\u3042\u3063\u305f\u308a\u306a\u3069\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u3082\u5197\u9577\u3067\u3057\u305f\u3002\u305d\u3057\u3066\u3001\u30d7\u30ed\u30b0\u30e9\u30de\u304c\u305d\u306e\u9803\u306e\u53e4\u3044\u77e5\u8b58\u3092\u66f4\u65b0\u3067\u304d\u3066\u3044\u306a\u3044\u3068\u3001\u4eca\u3067\u3082<span>Object<\/span>\u3092\u4f7f\u3044\u304c\u3061\u3067\u3059\u3002<\/p>\n<h3><span id=\"-Map-7\">\uff16-\uff13\uff0eMap\u304c\u5b58\u5728\u3059\u308b\u9650\u308a\u3001\u30ad\u30fc\u3068\u5024\u306f\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3055\u308c\u306a\u3044<\/span><\/h3>\n<p>Map\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u30e1\u30e2\u30ea\u4e0a\u306b\u3042\u308a\u7d9a\u3051\u308b\u306a\u3089\u3001<span>Map<\/span>\u304c\u6301\u3063\u3066\u3044\u308b\u30ad\u30fc\u3084\u5024\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3082\u305a\u3063\u3068\u30e1\u30e2\u30ea\u4e0a\u306b\u6b8b\u308a\u7d9a\u3051\u307e\u3059\u3002<span>Map<\/span>\u304c\u6301\u3063\u3066\u3044\u308b\u306e\u3067\u3001\u305d\u308c\u3089\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u4f7f\u308f\u308c\u3066\u3044\u308b\u3068\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u6642\u306b\u5224\u65ad\u3055\u308c\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n<p>\u3082\u3057\u3001\u96c6\u8a08\u51e6\u7406\u306a\u3069\u3067<span>Map<\/span>\u3092\u4e00\u6642\u7684\u306b\u4f7f\u3046\u3060\u3051\u306a\u3089\u30ed\u30fc\u30ab\u30eb\u5909\u6570\u3068\u3057\u305f\u308a\u3001\u30d5\u30a3\u30fc\u30eb\u30c9\u306a\u3069\u306e\u6bd4\u8f03\u7684\u5bff\u547d\u304c\u9577\u3044\u5909\u6570\u3068\u3059\u308b\u306a\u3089\u9069\u5207\u306a\u30bf\u30a4\u30df\u30f3\u30b0\u3067<span>remove\/clear<\/span>\u3057\u307e\u3057\u3087\u3046\u3002\u305d\u3046\u3057\u306a\u3044\u3068\u3001\u3044\u308f\u3086\u308b\u30e1\u30e2\u30ea\u30ea\u30fc\u30af\u306b\u7e4b\u304c\u3063\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n<p>\u307e\u305f\u3001<span>WeakHashMap<\/span>\u306a\u3069\u306e\u300c\u5f31\u53c2\u7167\u300d\u3092\u30b5\u30dd\u30fc\u30c8\u3059\u308b<span>Map<\/span>\u3092\u4f7f\u3063\u3066\u3082\u3088\u3044\u3067\u3057\u3087\u3046\u3002<span>WeakHashMap<\/span>\u306f\u3001\u30ad\u30fc\u304c<span>WeakHashMap<\/span>\u5916\u3067<span>Java<\/span>\u306e\u3069\u3053\u304b\u3089\u3082\u4f7f\u308f\u308c\u306a\u304f\u306a\u3063\u305f\u306a\u3089\u3001\u81ea\u52d5\u7684\u306b\u30ad\u30fc\u3092\u524a\u9664<span>(=<\/span>\u7d50\u679c\u7684\u306b\u5024\u3082\u524a\u9664\u3055\u308c\u308b<span>)<\/span>\u3057\u3066\u304f\u308c\u308b\u4fbf\u5229\u306a\u3082\u306e\u3067\u3059\u3002<\/p>\n<h3><span id=\"-keySetvaluesentrySetMap\">\uff16-\uff14\uff0ekeySet\/values\/entrySet\u306f\u5143\u306eMap\u3068\u9023\u52d5\u3059\u308b<\/span><\/h3>\n<p>keySet\/values\/entrySet\u3067\u53d6\u5f97\u3057\u305fSet\u3084Collection\u3078\u306e\u64cd\u4f5c\u306f\u3001\u5143\u306eMap\u3068\u9023\u52d5\u3057\u307e\u3059\u3002remove\u3084<span>clear<\/span>\u306f\u7279\u306b\u5f71\u97ff\u304c\u5927\u304d\u3044\u3067\u3059\u3002\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u30d0\u30b0\u3092\u9632\u304e\u305f\u304b\u3063\u305f\u308a\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u4e2d\u3067\u4e88\u671f\u305b\u306c\u52d5\u304d\u3092\u3055\u305b\u305f\u304f\u306a\u3044\u306a\u3089\u3001\u60c5\u5831\u306e\u8aad\u307f\u53d6\u308a\u3060\u3051\u306b\u3057\u305f\u65b9\u304c\u7121\u96e3\u3067\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nSet&lt;String&gt; keys = map.keySet();\r\nSystem.out.println(keys); \/\/ \u2192 [\u732b, \u72ac]\r\nkeys.remove(\"\u732b\"); \/\/ keySet\u3067\u53d6\u5f97\u3057\u305fSet\u304b\u3089\"\u732b\"\u3092\u524a\u9664\u3059\u308b\u3068\u2026\r\n\r\nSystem.out.println(map.containsKey(\"\u732b\")); \/\/ \u2192 false!! \u5143\u306eMap\u306e\u30ad\u30fc\u304b\u3089\u3082\"\u732b\"\u304c\u524a\u9664\u3055\u308c\u305f<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nCollection&lt;String&gt; values = map.values();\r\nSystem.out.println(values); \/\/ \u2192 [\u30de\u30a4\u30b1\u30eb, \u4f38\u4e4b\u52a9]\r\nvalues.remove(\"\u30de\u30a4\u30b1\u30eb\"); \/\/ values\u3067\u53d6\u5f97\u3057\u305fCollection\u304b\u3089\"\u30de\u30a4\u30b1\u30eb\"\u3092\u524a\u9664\u3059\u308b\u3068\u2026\r\n\r\nSystem.out.println(map.containsKey(\"\u732b\")); \/\/ \u2192 false!! \u5143\u306eMap\u304b\u3089\u3082\"\u30de\u30a4\u30b1\u30eb\"\u3068\u7d10\u4ed8\u3051\u305f\u30ad\u30fc\u304c\u524a\u9664\u3055\u308c\u305f<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; map = new HashMap&lt;&gt;();\r\nmap.put(\"\u732b\", \"\u30de\u30a4\u30b1\u30eb\");\r\nmap.put(\"\u72ac\", \"\u4f38\u4e4b\u52a9\");\r\n\r\nSet&lt;Map.Entry&lt;String, String&gt;&gt; entries = map.entrySet();\r\nSystem.out.println(entries); \/\/ \u2192 [\u732b=\u30de\u30a4\u30b1\u30eb, \u72ac=\u4f38\u4e4b\u52a9]\r\nentries.clear(); \/\/ \u2192 entrySet\u3067\u53d6\u5f97\u3057\u305fSet\u3092clear\u3059\u308b\r\n\r\nSystem.out.println(map.isEmpty()); \/\/ \u2192 true!! \u5143\u306eMap\u304b\u3089\u3082\u5168\u30ad\u30fc\u30fb\u5024\u306e\u5bfe\u5fdc\u304c\u524a\u9664\u3055\u308c\u305f<\/pre>\n<h3><span id=\"-Map-8\">\uff16-\uff15\uff0e\u5909\u66f4\u3067\u304d\u308b<span>Map<\/span>\u306f\u30af\u30e9\u30b9\u306e\u5916\u90e8\u306b\u516c\u958b\u3057\u306a\u3044<\/span><\/h3>\n<p>\u5185\u5bb9\u3092\u5909\u66f4\u3067\u304d\u308b<span>Map<\/span>\u306f\u3001\u30af\u30e9\u30b9\u306e\u5916\u90e8\u306b\u76f4\u63a5\u516c\u958b\u3057\u306a\u3044\u3088\u3046\u306b\u3057\u307e\u3057\u3087\u3046\u3002<span>Map<\/span>\u305d\u306e\u3082\u306e\u3092\u305d\u306e\u307e\u307e\u516c\u958b\u3057\u3066\u3057\u307e\u3046\u3068\u3001\u30af\u30e9\u30b9\u81ea\u8eab\u304c\u8cac\u4efb\u3092\u6301\u3063\u3066\u7ba1\u7406\u3059\u3079\u304d\u30c7\u30fc\u30bf\u3092\u3001\u30af\u30e9\u30b9\u306e\u5916\u304b\u3089\u5909\u66f4\u51fa\u6765\u3066\u3057\u307e\u3046\u3053\u3068\u306b\u306a\u308b\u304b\u3089\u3067\u3059\u3002\u3064\u307e\u308a\u3001\u30c7\u30fc\u30bf\u306e\u30ab\u30d7\u30bb\u30eb\u5316\u3092\u7dad\u6301\u3067\u304d\u306a\u304f\u306a\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class PublicMap {\r\n\t\/\/ Map\u3092\u30af\u30e9\u30b9\u306e\u4e2d\u3060\u3051\u3067\u4f7f\u3044\u305f\u3044\u3068\u601d\u3063\u3066\u3044\u3066\u3082\u2026\r\n\tprivate Map&lt;String, Integer&gt; map = new HashMap&lt;&gt;();\r\n\r\n\t\/\/ Map\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u305d\u306e\u307e\u307ereturn\u3059\u308b\u3068\u3001\u547c\u3073\u51fa\u3057\u5143\u3067put\/remove\/clear\u304c\u3067\u304d\u3066\u3057\u307e\u3046!!\r\n\tMap&lt;String, Integer&gt; getMap() {\r\n\t\treturn map;\r\n\t}\r\n}<\/pre>\n<p style=\"text-align: left;\">\u3069\u3046\u3057\u3066\u3082Map\u3092\u516c\u958b\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u306a\u3089\u3001\u4e0d\u5909\u306a(=\u5909\u66f4\u3067\u304d\u306a\u3044)Map\u3092\u4f5c\u308bCollections.unmodifiableMap\u3001\u3042\u308b\u3044\u306fMap.copyOf\u306a\u3069\u3092\u4f7f\u3044\u307e\u3057\u3087\u3046\u3002Collections.unmodifiableMap\u306a\u3089\u3001\u5143\u306b\u306a\u3063\u305fMap\u3068\u5185\u5bb9\u304c\u9023\u52d5\u3057\u307e\u3059\u3002Map.copyOf\u306f\u3001\u5143\u306eMap\u306e\u30b9\u30ca\u30c3\u30d7\u30b7\u30e7\u30c3\u30c8\u3067\u3042\u308a\u3001\u5185\u5bb9\u306f\u9023\u52d5\u3057\u307e\u305b\u3093\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class PublicMap {\r\n\tprivate Map&lt;String, Integer&gt; map = new HashMap&lt;&gt;();\r\n\r\n\t\/\/ \u4e0d\u5909\u306aMap\u306b\u3059\u308c\u3070\u3001\u547c\u3073\u51fa\u3057\u5143\u3067\u306fput\u3001remove\u3001clear\u306a\u3069\u306f\u3067\u304d\u306a\u304f\u306a\u308b\r\n\tMap&lt;String, Integer&gt; getMap() {\r\n\t\treturn Collections.unmodifiableMap(map);\r\n\t}\r\n}<\/pre>\n<p>\u3067\u3082\u3001\u4e0d\u5909\u306a<span>Map<\/span>\u3067\u3042\u3063\u3066\u3082\u3001<span>Map<\/span>\u306e\u30ad\u30fc\u3084\u5024\u304c\u6301\u3064\u30e1\u30bd\u30c3\u30c9\u305d\u306e\u3082\u306e\u306f\u547c\u3079\u3066\u3057\u307e\u3044\u307e\u3059\u3002<span>Map<\/span>\u304c\u6301\u3064\u30ad\u30fc\u3068\u5024\u3082\u4e0d\u5909\u306a\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306b\u3057\u3066\u5916\u90e8\u306b\u516c\u958b\u3067\u304d\u308b\u306a\u3089\u30d9\u30b9\u30c8\u3067\u3059\u304c\u3001\u3055\u3059\u304c\u306b\u305d\u3053\u307e\u3067\u3059\u308b\u3068\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u304c\u5927\u5909\u3067\u3059\u3057\u3001\u5c11\u3005\u73fe\u5b9f\u7684\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>\u3067\u3059\u304b\u3089\u3001<span>Map<\/span>\u305d\u306e\u3082\u306e\u3092\u30af\u30e9\u30b9\u306e\u5916\u90e8\u306b\u516c\u958b\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u304b\u306f\u3001\u3088\u304f\u3088\u304f\u8003\u3048\u307e\u3057\u3087\u3046\u3002<span>Map<\/span>\u3092\u7ba1\u7406\u3057\u3066\u3044\u308b\u30af\u30e9\u30b9\u306b\u5c02\u7528\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u7528\u610f\u3057\u3066\u3001\u30c7\u30fc\u30bf\u306e\u30c1\u30a7\u30c3\u30af\u3084\u5024\u306e\u53d6\u5f97\u3092\u3055\u305b\u308b\u3060\u3051\u3067\u3082\u5341\u5206\u306a\u30b1\u30fc\u30b9\u306f\u591a\u3044\u3068\u601d\u3044\u307e\u3059\u3088\u3002<\/p>\n<h3><span id=\"-IFMap\">\uff16-\uff16\uff0e\u30af\u30e9\u30b9\u5916\u90e8\u3068\u306e<span>IF<\/span>\u3067\u306f\u3001\u7d20\u306e<span>Map<\/span>\u3092\u306a\u308b\u3079\u304f\u4f7f\u308f\u306a\u3044<\/span><\/h3>\n<p>\u524d\u7bc0\u3068\u3082\u95a2\u9023\u3057\u307e\u3059\u304c\u3001<span>Map<\/span>\u304c\u4f7f\u308f\u308c\u308b<span>Java<\/span>\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u306b\u300c\u3046\u30fc\u3093<span>\u2026<\/span>\u300d\u3068\u611f\u3058\u308b\u6642\u306f\u3001\u7d20\u306e<span>Map<\/span>\u304c\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3084\u623b\u308a\u5024\u3067\u3042\u308b\u6642\u3067\u3059\u3002\u3057\u304b\u3082\u3001\u305d\u3093\u306a<span>Map<\/span>\u306f\u3001\u3048\u3066\u3057\u3066\u30ad\u30fc\u3082\u5024\u3082<span>Object<\/span>\u3067\u3059\u3002\u305d\u3046\u3044\u3046<span>Map<\/span>\u306f\u3001\u4f55\u306b\u3067\u3082\u4f7f\u3048\u308b\u4fbf\u5229\u3055\u3068\u5f15\u304d\u63db\u3048\u306b\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u3067\u672c\u6765\u8868\u73fe\u3059\u3079\u304d\u300c\u6587\u8108\u300d\u304c\u8ca7\u5f31\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class PlainMap {\r\n\t\/\/ \u30ad\u30fc\u30fb\u5024\u3067Object\u3092\u6271\u3046Map\u304c\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\r\n\tvoid method1(Map&lt;Object, Object&gt; param) {\r\n\t\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n\t}\r\n\r\n\t\/\/ \u30ad\u30fc\u30fb\u5024\u3067Object\u3092\u6271\u3046Map\u304c\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\r\n\tMap&lt;Object, Object&gt; method2() {\r\n\t\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n\t}\r\n}<\/pre>\n<p>\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u304c<span>Map<\/span>\u3092\u4f7f\u3046\u969b\u306f\u6c4e\u7528\u7684\u306b\u4f5c\u3089\u3056\u308b\u3092\u5f97\u306a\u3044\u306e\u3067\u3001\u30c7\u30fc\u30bf\u306e\u3084\u308a\u53d6\u308a\u306b<span>Map<\/span>\u3092\u4f7f\u3044\u3001\u304b\u3064\u30ad\u30fc\u3082\u5024\u3082<span>Object<\/span>\u306b\u306a\u308b\u306e\u306f\u4ed5\u65b9\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u3067\u3082\u3001\u81ea\u5206\u3067\u4f5c\u308b\u30d7\u30ed\u30b0\u30e9\u30e0\u306a\u3089\u3001\u3084\u308a\u3068\u308a\u3059\u308b\u30c7\u30fc\u30bf\u3092\u7684\u78ba\u306b\u8868\u73fe\u3057\u305f\u30af\u30e9\u30b9\u3092\u30e1\u30bd\u30c3\u30c9\u306f\u53d7\u3051\u53d6\u308b\u3079\u304d\u3067\u3059\u3057\u3001\u623b\u3059\u3079\u304d\u3067\u3059\u3002<\/p>\n<p>\u3042\u306a\u305f\u306e\u30af\u30e9\u30b9\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u679c\u305f\u3057\u3066\u672c\u5f53\u306b<span>Map<\/span>\u3092\u53d7\u3051\u53d6\u308a\u3001\u623b\u3055\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u306e\u304b\u3092\u81ea\u554f\u3057\u307e\u3057\u3087\u3046\u3002<span>Map<\/span>\u3092\u4f7f\u3046\u306e\u306f\u5b89\u6613\u306a\u9003\u3052\u9053\u3068\u3057\u3066\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u304b<span>? Map<\/span>\u3092\u7c21\u6613\u7684\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3068\u3057\u3066\u4f7f\u3044\u305f\u3044\u306e\u306a\u3089\u3001\u305d\u308c\u3092\u30af\u30e9\u30b9\u5316\u3057\u305f\u65b9\u304c\u3044\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u3042\u308b\u3079\u304d\u59ff\u3092\u3057\u3063\u304b\u308a\u3068\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<h3><span id=\"-Map-9\">\uff16-\uff17\uff0e\u5909\u6570\u306e\u578b\u3092<span>Map<\/span>\u3068\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u3069\u3061\u3089\u3067\u5ba3\u8a00\u3059\u3079\u304d\u304b<\/span><\/h3>\n<p>\u3053\u308c\u306f\u306a\u304b\u306a\u304b\u96e3\u3057\u3044\u3067\u3059\u3002\u539f\u5247\u306f\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306e<span>Map<\/span>\u3068\u3059\u3079\u304d\u3068\u8003\u3048\u3066\u3044\u307e\u3059\u3002\u5b9f\u88c5\u30af\u30e9\u30b9\u304c\u4f55\u3067\u3042\u308c\u3001<span>Map<\/span>\u3068\u3057\u3066\u62bd\u8c61\u7684\u306b\u6271\u3048\u308b\u3053\u3068\u304c\u3001\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3068\u3057\u3066\u306e<span>Map<\/span>\u304c\u6301\u3064\u5229\u70b9\u3067\u3042\u3063\u305f\u308a\u3001\u5b58\u5728\u610f\u7fa9\u3060\u3068\u8003\u3048\u3066\u3044\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u5909\u6570\u306e\u578b\u306f\u3001Map\u3068Map\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u3069\u3061\u3089\u3067\u3042\u308b\u3079\u304d?\u2460\r\nMap&lt;String, Integer&gt; map1 = new HashMap&lt;&gt;();\r\nHashMap&lt;String, Integer&gt; map2 = new HashMap&lt;&gt;();<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u5909\u6570\u306e\u578b\u306f\u3001Map\u3068Map\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306e\u3069\u3061\u3089\u3067\u3042\u308b\u3079\u304d?\u2461\r\nclass TypeOfMap {\r\n\tvoid method1(Map&lt;String, Integer&gt; map) {\r\n\t\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n\t}\r\n\r\n\tvoid method2(HashMap&lt;String, Integer&gt; map) {\r\n\t\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n\t}\r\n}<\/pre>\n<p>\u3067\u3082\u3001\u5b9f\u88c5\u30af\u30e9\u30b9\u3067\u3042\u308b\u3079\u304d\u304b\u3082<span>\u2026<\/span>\u3068\u8003\u3048\u308b\u6642\u3082\u3042\u308a\u307e\u3059\u3002\u306a\u305c\u306a\u3089\u3001<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306b\u3088\u308a\u3001\u5b9f\u969b\u306b\u30b5\u30dd\u30fc\u30c8\u3057\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9\u3084\u3001\u30e1\u30bd\u30c3\u30c9\u306e\u5b9f\u969b\u306e\u632f\u308b\u821e\u3044\u304c\u5b9f\u306f\u9055\u3046\u304b\u3089\u3067\u3059\u3002\u4f8b\u3048\u3070\u3001<span>TreeMap<\/span>\u306f<span>null<\/span>\u306e\u30ad\u30fc\u3068\u5024\u3092\u4f7f\u3048\u307e\u305b\u3093\u304c\u3001<span>HashMap<\/span>\u306f\u30ad\u30fc\u3082\u5024\u3082<span>null<\/span>\u3092\u4f7f\u3048\u307e\u3059\u3002<\/p>\n<p>\u305d\u3057\u3066\u3001<span>Map<\/span>\u306e<span>API<\/span>\u306b\u306f\u300c\u30aa\u30d7\u30b7\u30e7\u30f3\u306e\u64cd\u4f5c<span>(<\/span>\u82f1\u8a9e\u7248\u3060\u3068<span>optional operation)<\/span>\u300d\u306e\u8a18\u8ff0\u304c\u3042\u308a\u307e\u3059\u3002\u3064\u307e\u308a\u3001\u305d\u308c\u3089\u306f\u5b9f\u88c5\u30af\u30e9\u30b9\u3067\u5b8c\u5168\u306b\u52d5\u4f5c\u3057\u306a\u304f\u3066\u3082\u3044\u3044\u306e\u3067\u3059\u3002<span>Map<\/span>\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306b\u3042\u308b\u30e1\u30bd\u30c3\u30c9\u306a\u306e\u3067\u3069\u306e\u5177\u8c61\u30af\u30e9\u30b9\u3067\u3082\u547c\u3079\u307e\u3059\u304c\u3001\u547c\u3076\u5074\u304c\u610f\u56f3\u3059\u308b\u632f\u308b\u821e\u3044\u3092\u3059\u308b\u3053\u3068\u306f\u3001\u5fc5\u305a\u3057\u3082\u4fdd\u8a3c\u3055\u308c\u307e\u305b\u3093\u3002<\/p>\n<p>\u305d\u3046\u3044\u3046\u632f\u308b\u821e\u3044\u306e\u9055\u3044\u306f\u3001<span>Map<\/span>\u306e\u5b9f\u88c5\u30af\u30e9\u30b9\u306e<span>Javadoc<\/span>\u306b\u306f\u660e\u78ba\u306b\u66f8\u304b\u308c\u3066\u3044\u307e\u3059\u3002\u3067\u3059\u304c\u3001\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306e<span>Map<\/span>\u3067\u6271\u3046\u3068\u3001\u305d\u306e\u8fba\u308a\u306e\u4e8b\u60c5\u304c\u5206\u304b\u3089\u306a\u304f\u306a\u308a\u307e\u3059\u3002\u7d50\u5c40\u3001\u660e\u78ba\u306a\u7b54\u3048\u306f\u306a\u3044\u306e\u3067\u3059\u304c\u3001<span>Map<\/span>\u3092\u4f7f\u3063\u3066\u3044\u3066\u4f55\u304c\u554f\u984c\u304c\u8d77\u304d\u305f\u6642\u306f\u3001\u5b9f\u88c5\u30af\u30e9\u30b9\u304c\u4f55\u304b\u3092\u610f\u8b58\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<h2><span id=\"i-5\">\uff17\uff0e\u307e\u3068\u3081<\/span><\/h2>\n<p>Map\u306f\u30ad\u30fc\u3068\u5024\u3092\u30bb\u30c3\u30c8\u306b\u3057\u3066\u6271\u3046\u305f\u3081\u306e\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u3059\u3002\u30ad\u30fc\u3068\u3044\u3046\u4e2d\u9593\u7684\u306a\u3082\u306e\u3092\u9593\u306b\u631f\u3080\u3053\u3068\u3067\u3001\u9ad8\u901f\u30fb\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u7ba1\u7406\u304c\u884c\u3048\u307e\u3059\u3002<\/p>\n<p>Map\u306e\u64cd\u4f5c\u306f\u3001\u30ad\u30fc\u3068\u5024\u3092\u8a2d\u5b9a\u3059\u308b\u3001\u30ad\u30fc\u306b\u7d10\u3065\u304f\u5024\u3092\u5f97\u308b\u3001\u30ad\u30fc\u3092\u524a\u9664\u3059\u308b\u3001\u30ad\u30fc\u30fb\u5024\u3092\u53d6\u5f97\u3059\u308b\u304c\u57fa\u672c\u7684\u306a\u3082\u306e\u3067\u3059\u3002\u305d\u308c\u3089\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u3001\u30c7\u30fc\u30bf\u306e\u96c6\u8a08\u30fb\u5206\u985e\u30fb\u30ad\u30e3\u30c3\u30b7\u30e5\u306a\u3069\u306b\u7528\u3044\u308b\u306e\u304c\u3001<span>Map<\/span>\u306e\u3088\u304f\u3042\u308b\u4f7f\u3044\u65b9\u3067\u3059\u3002<\/p>\n<p>Map\u306f\u30ad\u30fc\u3084\u5024\u306b\u4efb\u610f\u306e\u30af\u30e9\u30b9\u3092\u4f7f\u3048\u307e\u3059\u3002\u3067\u3059\u304c\u3001\u6271\u3048\u308b\u7bc4\u56f2\u304c\u5e83\u3059\u304e\u308b\u3068\u9006\u306b\u53ce\u62fe\u304c\u3064\u304b\u306a\u304f\u306a\u308a\u3001\u30b4\u30df\u7bb1\u306e\u3088\u3046\u306b\u306a\u308a\u304c\u3061\u3067\u3059\u3002\u578b\u5f15\u6570\u306a\u3069\u3092\u4f7f\u3063\u3066<span>Map<\/span>\u3067\u7ba1\u7406\u3059\u308b\u5bfe\u8c61\u3092\u660e\u78ba\u306b\u3059\u308b\u306e\u304c\u3001\u4e0a\u624b\u306a<span>Map<\/span>\u306e\u4f7f\u3044\u65b9\u3067\u3059\u3002<\/p>\n<p>\u305d\u3057\u3066\u3001\u4fbf\u5229\u3060\u304b\u3089\u3068\u8a00\u3063\u3066\u3044\u305f\u305a\u3089\u306b\u30af\u30e9\u30b9\u306e\u5185\u90e8\u3067\u6301\u3064<span>Map<\/span>\u3092\u5916\u90e8\u306b\u516c\u958b\u3059\u308b\u3053\u3068\u306f\u3001\u30c7\u30fc\u30bf\u306e\u30ab\u30d7\u30bb\u30eb\u5316\u3092\u7834\u308b\u3053\u3068\u306b\u3082\u7e4b\u304c\u308a\u304b\u306d\u306a\u3044\u5371\u967a\u306a\u884c\u70ba\u3067\u3059\u3002\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u306e\u5229\u70b9\u3092\u751f\u304b\u3059\u305f\u3081\u306b\u3082\u3001<span>Map<\/span>\u306f\u9069\u6750\u9069\u6240\u3067\u7528\u3044\u307e\u3057\u3087\u3046<span>!!<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Map\u306f\u3001Java\u3067\u30ad\u30fc\u3068\u5024\u3092\u30bb\u30c3\u30c8\u306b\u3057\u3066\u6271\u3044\u305f\u3044\u6642\u306b\u4f7f\u3046\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u3059\u3002 \u4ed6\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u3067\u3001\u30cf\u30c3\u30b7\u30e5\u30c6\u30fc\u30d6\u30eb\u30fb\u30c7\u30a3\u30af\u30b7\u30e7\u30ca\u30ea\u30fb\u9023\u60f3\u914d\u5217\u306a\u3069\u3068\u547c\u3070\u308c\u308b\u3082\u306e\u306b\u8fd1\u3044\u4f7f\u3044\u65b9\u304c\u3067\u304d\u308b\u3082\u306e\u3067\u3059\u3002 Map\u306e\u6a5f\u80fd\u306f\u30b7\u30f3\u30d7\u30eb\u3067\u3059 [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":804,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[14],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/1410"}],"collection":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/comments?post=1410"}],"version-history":[{"count":8,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/1410\/revisions"}],"predecessor-version":[{"id":5777,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/1410\/revisions\/5777"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/media\/804"}],"wp:attachment":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/media?parent=1410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/categories?post=1410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}