{"id":948,"date":"2018-11-19T12:00:28","date_gmt":"2018-11-19T03:00:28","guid":{"rendered":"https:\/\/www.bold.ne.jp\/engineer-club\/?p=948"},"modified":"2025-09-17T13:51:01","modified_gmt":"2025-09-17T04:51:01","slug":"java-compareto","status":"publish","type":"post","link":"https:\/\/www.bold.ne.jp\/engineer-club\/java-compareto","title":{"rendered":"Java\u306ecompareTo\u3068\u306f\uff1f\u30bd\u30fc\u30c8\u3092\u81ea\u7531\u81ea\u5728\u306b\u64cd\u308b\u305f\u3081\u306ecompareTo\u306e\u4f7f\u3044\u65b9"},"content":{"rendered":"<p>Java\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9<span>Comparable<\/span>\u306e\u30e1\u30bd\u30c3\u30c9<span>compareTo<\/span>\u3067\u306f\u3001\u5927\u5c0f\u6bd4\u8f03\u3092\u884c\u3044\u307e\u3059\u3002\u3053\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3092\u5b9f\u88c5\u3057\u305f\u30af\u30e9\u30b9\u306f\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u3001\u7d50\u679c\u3001\u30bd\u30fc\u30c8\u3092\u884c\u3048\u308b\u3088\u3046\u306b\u306a\u308b\u306e\u3067\u3059\u3002<\/p>\n<p>\u3069\u3093\u306a\u30d7\u30ed\u30b0\u30e9\u30e0\u3067\u3082\u3001\u30bd\u30fc\u30c8\u306f\u6b20\u304b\u305b\u306a\u3044\u51e6\u7406\u3067\u3059\u3002<span>Java<\/span>\u306e\u30bd\u30fc\u30c8\u306f\u3053\u306e<span>Comparable<\/span>\u3068\u3001\u3082\u3046\u4e00\u3064\u306e\u5927\u5c0f\u6bd4\u8f03\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3067\u3042\u308b<span>Comparator<\/span>\u304c\u652f\u3048\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001<strong><\/strong><span class=\"f-marker-p\"><strong>Comparable.compareTo\u306b\u3064\u3044\u3066<\/strong><\/span>\u521d\u5fc3\u8005\u5411\u3051\u306b\u4e00\u304b\u3089\u8aac\u660e\u3057\u307e\u3059\u3002\u4fbf\u5229\u306a\u4f7f\u3044\u65b9\u3084<span>Comparator<\/span>\u3068\u306e\u4f7f\u3044\u5206\u3051\u306b\u3064\u3044\u3066\u3082\u8aac\u660e\u3057\u307e\u3059\u306e\u3067\u3001\u305c\u3072\u8aad\u3093\u3067\u3044\u3063\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<p>\u306a\u304a\u300c<span>compareTo<\/span>\u306f\u5f8c\u304b\u3089\u52c9\u5f37\u3059\u308b\u306e\u3067\u3001\u4eca\u306f\u3068\u306b\u304b\u304f\u30bd\u30fc\u30c8\u306e\u3084\u308a\u65b9\u3092<span>!!<\/span>\u300d\u3068\u3044\u3046\u65b9\u306f\u3001\u300c<strong>4.Comparable\u3092\u4f7f\u3063\u305f\u30bd\u30fc\u30c8<\/strong>\u300d\u304c\u307e\u3055\u306b\u305d\u308c\u3067\u3059<span>!!<\/span><\/p>\n<p>\u203b\u3053\u306e\u8a18\u4e8b\u306e\u30b5\u30f3\u30d7\u30eb\u306f\u3001<span>Java 10<\/span>\u306e\u74b0\u5883\u3067\u52d5\u4f5c\u78ba\u8a8d\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<div id=\"toc_container\" class=\"no_bullets\"><p class=\"toc_title\">\u76ee\u6b21<\/p><ul class=\"toc_list\"><li><a href=\"#JavaComparablecompareTo\">\uff11\uff0e\u3010Java\u3011Comparable.compareTo\u306f\u30bd\u30fc\u30c8\u3067\u4f7f\u3046<\/a><ul><li><a href=\"#-ComparablecompareTo\">\uff11-\uff11\uff0eComparable.compareTo\u306f\u5927\u5c0f\u6bd4\u8f03\u3092\u3059\u308b<\/a><\/li><li><a href=\"#i\">\uff11-\uff12\uff0e\u30bd\u30fc\u30c8\u306b\u306f\u5927\u5c0f\u6bd4\u8f03\u304c\u5fc5\u8981\u4e0d\u53ef\u6b20\uff01<\/a><\/li><\/ul><\/li><li><a href=\"#JavaComparablecompareTo-2\">\uff12\uff0e\u3010Java\u3011Comparable.compareTo\u306e\u30b3\u30c4<\/a><ul><li><a href=\"#-3\">\uff12-\uff11\uff0e\u5224\u65ad\u7d50\u679c\u306f\u5c0f\u3055\u3044\u30fb\u7b49\u3057\u3044\u30fb\u5927\u304d\u3044\u306e3\u7a2e\u985e\u3060\u3051<\/a><\/li><li><a href=\"#i-2\">\uff12-\uff12\uff0e\u5927\u5c0f\u6bd4\u8f03\u306f\u76f8\u624b\u3088\u308a\u81ea\u5206\u304c\u5927\u304d\u3044\u304b\u5c0f\u3055\u3044\u304b<\/a><\/li><li><a href=\"#-IntegercompareTo\">\uff12-\uff13\uff0eInteger\u3067compareTo\u3092\u8a66\u3057\u3066\u307f\u308b<\/a><\/li><\/ul><\/li><li><a href=\"#JavaComparablecompareTo-3\">\uff13\uff0e\u3010Java\u3011Comparable.compareTo\u306e\u5b9f\u88c5\u4f8b<\/a><ul><li><a href=\"#-compareTo\">\uff13-\uff11\uff0ecompareTo\u306e\u57fa\u672c\u5f62<\/a><\/li><li><a href=\"#i-3\">\uff13-\uff12\uff0e\u8907\u6570\u306e\u6761\u4ef6\u3067\u5927\u5c0f\u6bd4\u8f03\u3092\u3057\u305f\u3044\u5834\u5408<\/a><\/li><li><a href=\"#-compare\">\uff13-\uff13\uff0e\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u5927\u5c0f\u6bd4\u8f03\u306fcompare\u3067\u697d\u3057\u3088\u3046\uff01<\/a><\/li><li><a href=\"#-throw\">\uff13-\uff14\uff0e\u6bd4\u8f03\u3067\u304d\u306a\u3044\u306a\u3089\u4f8b\u5916\u3092throw\u3057\u3088\u3046<\/a><\/li><\/ul><\/li><li><a href=\"#JavaComparable\">\uff14\uff0e\u3010Java\u3011Comparable\u3092\u4f7f\u3063\u305f\u30bd\u30fc\u30c8<\/a><ul><li><a href=\"#-ArrayssortObject\">\uff14-\uff11\uff0eArrays.sort(Object[])\u3067\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/a><\/li><li><a href=\"#-CollectionssortListreverseListList\">\uff14-\uff12\uff0eCollections.sort(List)\/reverse(List)\u3067List\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/a><\/li><li><a href=\"#-StreamsortedStream\">\uff14-\uff13\uff0eStream.sorted()\u3067Stream\u306e\u7d50\u679c\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/a><\/li><li><a href=\"#-TreeSetTreeMap\">\uff14-\uff14\uff0eTreeSet\/TreeMap\u304b\u3089\u30bd\u30fc\u30c8\u6e08\u306e\u5024\/\u30ad\u30fc\u3092\u53d6\u5f97\u3059\u308b<\/a><\/li><\/ul><\/li><li><a href=\"#Comparatorcompare\">\uff15\uff0e\u3010\u95a2\u9023\u3011Comparator.compare\u306e\u4f7f\u3044\u65b9<\/a><\/li><li><a href=\"#JavaAPIcompareTo\">\uff16\uff0e\u3010\u53c2\u8003\u3011Java\u6a19\u6e96API\u306e\u30af\u30e9\u30b9\u3067\u306ecompareTo\u306b\u3064\u3044\u3066<\/a><ul><li><a href=\"#-Date\">\uff16-\uff11\uff0eDate\u306f\u30df\u30ea\u79d2\u307e\u3067\u306e\u6642\u9593\u3092\u6301\u3063\u3066\u3044\u308b<\/a><\/li><li><a href=\"#-BigDecimalcompareTo\">\uff16-\uff12\uff0eBigDecimal\u306ecompareTo\u306f\u7cbe\u5ea6\u3092\u610f\u8b58\u3057\u306a\u3044<\/a><\/li><li><a href=\"#i-4\">\uff16-\uff13\uff0e\u7b26\u53f7\u306a\u3057\u6574\u6570\u306e\u5927\u5c0f\u6bd4\u8f03\u306b\u306f\u5c02\u7528\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308b<\/a><\/li><\/ul><\/li><li><a href=\"#i-5\">\uff17\uff0e\u307e\u3068\u3081<\/a><\/li><\/ul><\/div>\n<h2><span id=\"JavaComparablecompareTo\">\uff11\uff0e\u3010Java\u3011Comparable.compareTo\u306f\u30bd\u30fc\u30c8\u3067\u4f7f\u3046<\/span><\/h2>\n<h3><span id=\"-ComparablecompareTo\">\uff11-\uff11\uff0eComparable.compareTo\u306f\u5927\u5c0f\u6bd4\u8f03\u3092\u3059\u308b<\/span><\/h3>\n<p>\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9Comparable\u306e\u62bd\u8c61\u30e1\u30bd\u30c3\u30c9compareTo\u306f\u3001\u81ea\u5206\u81ea\u8eab\u3068\u5f15\u6570\u306e\u30af\u30e9\u30b9\u3092\u5927\u5c0f\u6bd4\u8f03\u3057\u305f\u7d50\u679c\u3092\u6574\u6570\u3067\u623b\u3059\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<p>\u307e\u305a\u306f<span>compareTo<\/span>\u306e\u4f7f\u3044\u65b9\u3068\u623b\u308a\u5024\u306b\u3064\u3044\u3066\u3001\u4ee5\u4e0b\u3060\u3051\u3057\u3063\u304b\u308a\u3068\u899a\u3048\u3066\u304a\u3051\u3070\u3001<span>compareTo<\/span>\u3092\u4f7f\u3046\u4e0a\u3067\u306f\u30d0\u30c3\u30c1\u30ea\u3067\u3059<span>!!<\/span><\/p>\n<blockquote>\n<p>\u4f7f\u3044\u65b9<\/p>\n<p>\u3000\u3000\u3000\u6bd4\u8f03\u3059\u308b\u3082\u306e.compareTo(\u6bd4\u8f03\u3055\u308c\u308b\u3082\u306e)<\/p>\n<p>\u3000\u3000\u3000\u2192\u5927\u5c0f\u6bd4\u8f03\u3057\u305f\u7d50\u679c\u306e\u6574\u6570\u304c\u623b\u308b<\/p>\n<p>\u5927\u5c0f\u6bd4\u8f03\u306e\u7d50\u679c<\/p>\n<p>\u3000\u3000\u3000\u6bd4\u8f03\u3059\u308b\u3082\u306e &lt; \u6bd4\u8f03\u3055\u308c\u308b\u3082\u306e\uff1a-1\u4ee5\u4e0b\u306e\u6574\u6570<\/p>\n<p>\u3000\u3000\u3000\u6bd4\u8f03\u3059\u308b\u3082\u306e = \u6bd4\u8f03\u3055\u308c\u308b\u3082\u306e\uff1a0<\/p>\n<p>\u3000\u3000\u3000\u6bd4\u8f03\u3059\u308b\u3082\u306e &gt; \u6bd4\u8f03\u3055\u308c\u308b\u3082\u306e\uff1a1\u4ee5\u4e0a\u306e\u6574\u6570<\/p>\n<\/blockquote>\n<h3><span id=\"i\">\uff11-\uff12\uff0e\u30bd\u30fc\u30c8\u306b\u306f\u5927\u5c0f\u6bd4\u8f03\u304c\u5fc5\u8981\u4e0d\u53ef\u6b20\uff01<\/span><\/h3>\n<p>\u914d\u5217\u3084\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u30bd\u30fc\u30c8\u306f\u983b\u7e41\u306b\u4f7f\u3044\u307e\u3059\u3002\u4f55\u304b\u3092\u65e5\u4ed8\u5225\u306b\u30bd\u30fc\u30c8\u3057\u305f\u308a\u3001\u96c6\u8a08\u7d50\u679c\u306e\u4ef6\u6570\u306a\u3069\u3067\u6607\u9806<span>\/<\/span>\u964d\u9806\u306b\u30bd\u30fc\u30c8\u3057\u305f\u308a\u306a\u3069\u3067\u3059\u3002<\/p>\n<p>\u305d\u3093\u306a\u30bd\u30fc\u30c8\u3092\u884c\u3046\u306b\u306f\u3001\u914d\u5217\u3084\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306b\u683c\u7d0d\u3055\u308c\u3066\u3044\u308b\u8981\u7d20\u540c\u58eb\u306e\u5927\u5c0f\u6bd4\u8f03\u304c\u5fc5\u8981\u3067\u3059\u3002\u30d0\u30d6\u30eb\u30bd\u30fc\u30c8\u3001\u30de\u30fc\u30b8\u30bd\u30fc\u30c8\u3001\u30af\u30a4\u30c3\u30af\u30bd\u30fc\u30c8\u306a\u3069\u3001\u3069\u3093\u306a\u30bd\u30fc\u30c8\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u3092\u4f7f\u3046\u306b\u3057\u3066\u3082\u3001\u5927\u5c0f\u6bd4\u8f03\u306f\u6b20\u304b\u305b\u307e\u305b\u3093\u3002<\/p>\n<p>int\u306a\u3069\u306e\u6570\u5b57\u306a\u3089\u5927\u5c0f\u6bd4\u8f03\u306f\u81ea\u660e\u3067\u3059\u3002\u3067\u3082<span>Java<\/span>\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u306a\u306e\u3067\u3001\u30af\u30e9\u30b9\u540c\u58eb\u306e\u5927\u5c0f\u6bd4\u8f03\u304c\u5fc5\u8981\u3067\u3059\u304c\u3001\u30af\u30e9\u30b9\u306b\u306f\u6570\u5b57\u306e\u3088\u3046\u306b\u81ea\u660e\u306a\u5224\u65ad\u57fa\u6e96\u304c\u306a\u3044\u306e\u3067\u3001\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u304c\u5927\u5c0f\u3092\u6559\u3048\u3066\u3042\u3052\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002\u305d\u306e\u305f\u3081\u306b\u4f7f\u3046\u306e\u304c<span>Comparable.compareTo()<\/span>\u3067\u3059\u3002<\/p>\n<h2><span id=\"JavaComparablecompareTo-2\">\uff12\uff0e\u3010Java\u3011Comparable.compareTo\u306e\u30b3\u30c4<\/span><\/h2>\n<h3><span id=\"-3\">\uff12-\uff11\uff0e\u5224\u65ad\u7d50\u679c\u306f\u5c0f\u3055\u3044\u30fb\u7b49\u3057\u3044\u30fb\u5927\u304d\u3044\u306e<span>3<\/span>\u7a2e\u985e\u3060\u3051<\/span><\/h3>\n<p>\u307e\u305a\u306f\u3001<span>compareTo<\/span>\u304c\u3069\u3046\u3044\u3046\u3082\u306e\u304b\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<span>Comparable.compareTo<\/span>\u306e\u30e1\u30bd\u30c3\u30c9\u5ba3\u8a00\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int compareTo(T o)\r\n\t\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u6307\u5b9a\u3055\u308c\u305f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u9806\u5e8f\u3092\u6bd4\u8f03\u3057\u307e\u3059\u3002\r\n\u30d1\u30e9\u30e1\u30fc\u30bf:\r\n\to -\u6bd4\u8f03\u5bfe\u8c61\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3002\r\n\u623b\u308a\u5024:\r\n\t\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u6307\u5b9a\u3055\u308c\u305f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3088\u308a\u5c0f\u3055\u3044\u5834\u5408\u306f\u8ca0\u306e\u6574\u6570\u3001\u7b49\u3057\u3044\u5834\u5408\u306f\u30bc\u30ed\u3001\u5927\u304d\u3044\u5834\u5408\u306f\u6b63\u306e\u6574\u6570<\/pre>\n<p>\u3053\u3053\u3067\u3001\u5b9f\u7528\u4e0a\u3067\u610f\u8b58\u3059\u3079\u304d\u306a\u306e\u306f\u3001\u623b\u308a\u5024\u304c<span>0<\/span>\u304b\u3069\u3046\u304b\u3001\u305d\u3057\u3066<span>0<\/span>\u3088\u308a\u5927\u304d\u3044\u304b\u5c0f\u3055\u3044\u304b\u3067\u3059\u3002<\/p>\n<p>\u8aac\u660e\u306b\u306f\u8ca0\u306e\u6574\u6570\u30fb\u6b63\u306e\u6574\u6570\u3068\u3042\u308a\u307e\u3059\u304c\u3001\u5358\u306b<span>0<\/span>\u3068\u6bd4\u3079\u3066\u5927\u304d\u3044\u306e\u304b\u5c0f\u3055\u3044\u306e\u304b\u3092\u77e5\u308a\u305f\u3044\u3060\u3051<span>\u2026<\/span>\u3059\u306a\u308f\u3061<span>3<\/span>\u3064\u306e\u72b6\u614b\u3092\u533a\u5225\u3057\u305f\u3044\u3060\u3051\u306a\u306e\u3067\u3001\u6570\u5b57\u306e\u7d76\u5bfe\u5024\u81ea\u4f53\u306b\u306f\u610f\u5473\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u4e00\u822c\u7684\u306b\u306f<span>-1<\/span>\u3001<span>0<\/span>\u3001<span>1<\/span>\u304c\u4f7f\u308f\u308c\u307e\u3059\u3057\u3001<span>JDK<\/span>\u306e\u30bd\u30fc\u30b9\u30b3\u30fc\u30c9\u3067\u3082<span>(<\/span>\u5927\u4f53\u306f<span>)<\/span>\u540c\u3058\u3067\u3059\u3002<\/p>\n<h3><span id=\"i-2\">\uff12-\uff12\uff0e\u5927\u5c0f\u6bd4\u8f03\u306f\u76f8\u624b\u3088\u308a\u81ea\u5206\u304c\u5927\u304d\u3044\u304b\u5c0f\u3055\u3044\u304b<\/span><\/h3>\n<p>\u899a\u3048\u3066\u304a\u304f\u3079\u304d\u306a\u306e\u306f\u3001\u6bd4\u8f03\u300c\u3059\u308b\u300d\u5074\u3068\u6bd4\u8f03\u300c\u3055\u308c\u308b\u300d\u5074\u306e\u95a2\u4fc2\u3067\u3059\u3002\u6bd4\u8f03\u3059\u308b\u5074\u306e<span>compareTo<\/span>\u306f\u3001\u6bd4\u8f03\u3055\u308c\u308b\u5074\u3092\u5f15\u6570\u306b\u547c\u3073\u51fa\u3055\u308c\u307e\u3059\u3002\u5927\u5c0f\u6bd4\u8f03\u306e\u7d50\u679c\u306f\u3053\u308c\u3092\u524d\u63d0\u3068\u3057\u305f\u623b\u308a\u5024\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u3064\u307e\u308a\u3001\u6bd4\u8f03\u3059\u308b\u5074\u300c\u304b\u3089\u300d\u898b\u305f\u8996\u70b9\u306b\u306a\u308a\u307e\u3059\u3002\u81ea\u5206\u304c\u6bd4\u8f03\u3055\u308c\u308b\u5074\u3088\u308a\u5927\u304d\u3044\u304b\u5c0f\u3055\u3044\u304b\u3001\u3042\u308b\u3044\u306f\u540c\u3058\u304b\u304c\u3001<span>compareTo<\/span>\u306e\u623b\u308a\u5024\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u3001\u6570\u5024\u306e<span>50<\/span>\u304c\u6bd4\u8f03\u3059\u308b\u5074\u3001<span>100<\/span>\u304c\u6bd4\u8f03\u3055\u308c\u308b\u5074\u3060\u3068\u3057\u307e\u3059\u3002<span>50<\/span>\u304b\u3089\u3059\u308b\u3068\u81ea\u5206\u306f<span>100<\/span>\u3088\u308a\u3082\u300c\u5c0f\u3055\u3044\u300d\u306e\u3067\u3001\u623b\u308a\u5024\u306f<span>-1<\/span>\u4ee5\u4e0b\u306e\u6574\u6570\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<h3><span id=\"-IntegercompareTo\">\uff12-\uff13\uff0eInteger\u3067<span>compareTo<\/span>\u3092\u8a66\u3057\u3066\u307f\u308b<\/span><\/h3>\n<p>\u3055\u3066\u3001\u524d\u8ff0\u306e\u3068\u304a\u308a\u3001<span>Comparable<\/span>\u306f\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306a\u306e\u3067\u3001\u4f55\u304b\u306e\u30af\u30e9\u30b9\u306b\u5b9f\u88c5<span>(implements)<\/span>\u3057\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002<span>int<\/span>\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9<span>Integer<\/span>\u306f<span>Comparable<\/span>\u3092\u5b9f\u88c5\u3057\u3066\u3044\u307e\u3059\u306e\u3067\u3001\u3053\u308c\u3067\u3069\u3046\u3044\u3046\u7d50\u679c\u306b\u306a\u308b\u304b\u8a66\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Integer zero = Integer.valueOf(0);\r\nInteger zero2 = Integer.valueOf(0);\r\nInteger one = Integer.valueOf(1);\r\nInteger negativeOne = Integer.valueOf(-1);\r\nInteger million = Integer.valueOf(1000000);\r\n\r\nSystem.out.println(zero.compareTo(one)); \/\/ 0\u30681\u3092\u6bd4\u8f03\u3059\u308b\u21920\u306f1\u3088\u308a\u3082\u5c0f\u3055\u3044\u2192\u300c-1\u300d\u304c\u623b\u308a\u5024\r\nSystem.out.println(zero.compareTo(negativeOne)); \/\/ 0\u3068-1\u3092\u6bd4\u8f03\u3059\u308b\u21920\u306f-1\u3088\u308a\u3082\u5927\u304d\u3044\u2192\u300c1\u300d\u304c\u623b\u308a\u5024\r\nSystem.out.println(one.compareTo(negativeOne)); \/\/ 1\u3068-1\u3092\u6bd4\u8f03\u3059\u308b\u21921\u306f-1\u3088\u308a\u3082\u5927\u304d\u3044\u2192\u300c1\u300d\u304c\u623b\u308a\u5024\r\nSystem.out.println(negativeOne.compareTo(one)); \/\/ -1\u30681\u3092\u6bd4\u8f03\u3059\u308b\u2192-1\u306f-1\u3088\u308a\u3082\u5c0f\u3055\u3044\u2192\u300c-1\u300d\u304c\u623b\u308a\u5024\r\nSystem.out.println(zero.compareTo(zero2)); \/\/ 0\u30680\u3092\u6bd4\u8f03\u3059\u308b\u21920\u306f0\u3068\u540c\u3058\u5927\u304d\u3055\u2192\u300c0\u300d\u304c\u623b\u308a\u5024\r\nSystem.out.println(zero.compareTo(million)); \/\/ 0\u30681000000\u3092\u6bd4\u8f03\u3059\u308b\u2192-1\u3001\u5dee\u304c\u3044\u304f\u3089\u5927\u304d\u304f\u3066\u3082\u623b\u308a\u5024\u304c0\u3088\u308a\u5c0f\u3055\u3051\u308c\u3070\u3044\u3044!!<\/pre>\n<p>\u304d\u3061\u3093\u3068\u30e1\u30bd\u30c3\u30c9\u306e\u4ed5\u69d8\u3069\u304a\u308a\u306e\u623b\u308a\u5024\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u306d\u3002\u3053\u308c\u304c<span>compareTo<\/span>\u306e\u52d5\u304d\u3067\u3059\u3002<span>Comparable<\/span>\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308b\u540c\u3058\u30af\u30e9\u30b9\u540c\u58eb\u306a\u3089\u3001\u5168\u3066\u3053\u306e\u3088\u3046\u306b\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b\u306e\u3067\u3059\u3002<\/p>\n<p>\u203b\u300c<span>6.<\/span>\u3010\u53c2\u8003\u3011<span>Java<\/span>\u6a19\u6e96<span>API<\/span>\u306e\u30af\u30e9\u30b9\u3067\u306e<span>compareTo<\/span>\u306b\u3064\u3044\u3066\u300d\u306b\u3001<span>Integer<\/span>\u4ee5\u5916\u306e<span>Java<\/span>\u6a19\u6e96<span>API<\/span>\u306e\u826f\u304f\u4f7f\u3046\u30af\u30e9\u30b9\u3067<span>compareTo<\/span>\u3092\u884c\u3063\u305f\u5834\u5408\u306b\u3069\u3046\u306a\u308b\u304b\u3092\u8a18\u8f09\u3057\u3066\u3042\u308a\u307e\u3059\u3002<\/p>\n<h2><span id=\"JavaComparablecompareTo-3\">\uff13\uff0e\u3010Java\u3011Comparable.compareTo\u306e\u5b9f\u88c5\u4f8b<\/span><\/h2>\n<h3><span id=\"-compareTo\">\uff13-\uff11\uff0ecompareTo\u306e\u57fa\u672c\u5f62<\/span><\/h3>\n<p>\u524d\u7ae0\u3067\u306fcompareTo\u3092Integer\u306a\u3069\u3067\u8a66\u3057\u3066\u307f\u307e\u3057\u305f\u3002\u6b21\u306f\u81ea\u5206\u3067\u4f5c\u3063\u305f\u30af\u30e9\u30b9\u3067compareTo\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u4ee5\u4e0b\u306f\u4f55\u304b\u306e\u30e6\u30fc\u30b6(User)\u306e\u3064\u3082\u308a\u3067\u3001int no\u306f\u30e6\u30fc\u30b6\u3054\u3068\u306e\u756a\u53f7\u3067\u3059\u3002\u3053\u306e\u756a\u53f7\u3092\u30ad\u30fc\u306bcompareTo\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class User implements Comparable {\r\n\tint no;\r\n\r\n\tUser(int no) {\r\n\t\tthis.no = no;\r\n\t}\r\n\r\n\tpublic int compareTo(Object o) {\r\n\t\tUser u = (User) o;\r\n\r\n\t\t\/\/ \u81ea\u5206\u306e\u65b9\u304c\u6bd4\u8f03\u5148\u3088\u308a\u300c\u5c0f\u3055\u3044\u300d\u306a\u3089\u8ca0\u306e\u6574\u6570\u3092\u8fd4\u3059\r\n\t\tif (this.no &lt; u.no) {\r\n\t\t\treturn -1;\r\n\t\t}\r\n\r\n\t\t\/\/ \u81ea\u5206\u306e\u65b9\u304c\u6bd4\u8f03\u5148\u3088\u308a\u300c\u5927\u304d\u3044\u300d\u306a\u3089\u6b63\u306e\u6574\u6570\u3092\u8fd4\u3059\r\n\t\tif (this.no &gt; u.no) {\r\n\t\t\treturn 1;\r\n\t\t}\r\n\r\n\t\t\/\/ \u3053\u3053\u306b\u6765\u308b\u3068\u3044\u3046\u3053\u3068\u306f\u6bd4\u8f03\u5148\u3068\u300c\u7b49\u3057\u3044\u300d\u306e\u3067\u30010\u3092\u8fd4\u3059\r\n\t\treturn 0;\r\n\t}\r\n\r\n\tpublic static void main(String[] args) {\r\n\t\tUser u1 = new User(1);\r\n\t\tUser u2 = new User(2);\r\n\t\tUser u3 = new User(3);\r\n\r\n\t\tSystem.out.println(u1.compareTo(u2)); \/\/ -1\u3001\u756a\u53f71\u30682\u3092\u6bd4\u8f03\u3057\u305f\u7d50\u679c\r\n\t\tSystem.out.println(u3.compareTo(u1)); \/\/ 1\u3001\u756a\u53f73\u30681\u3092\u6bd4\u8f03\u3057\u305f\u7d50\u679c\r\n\t\tSystem.out.println(u1.compareTo(u1)); \/\/ 0\u3001u1\u540c\u58eb\u3067\u6bd4\u3079\u308b\u306a\u3089\u3001\u540c\u3058\u756a\u53f7(\u4e21\u65b91)\u306a\u306e\u3067\r\n\t}\r\n}<\/pre>\n<p>\u3053\u308c\u304ccompareTo\u306e\u57fa\u672c\u5f62\u3067\u3059\u3002compareTo\u306e\u5f15\u6570\u306f\u6bd4\u8f03\u5148\u306e\u4f55\u304b\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3067\u3059\u3002\u3067\u3082\u3001\u578b\u304cObject\u306e\u307e\u307e\u3067\u306f\u6bd4\u8f03\u3057\u3088\u3046\u304c\u306a\u3044\u306e\u3067\u3001\u81ea\u5206\u81ea\u8eab\u306e\u30af\u30e9\u30b9\u306b\u30ad\u30e3\u30b9\u30c8\u3057\u3066\u304b\u3089\u6bd4\u8f03\u306b\u4f7f\u3046\u5024\u3092\u53c2\u7167\u3057\u3001\u5927\u5c0f\u6bd4\u8f03\u306e\u7d50\u679c\u3092\u623b\u3057\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u4f8b\u3067\u306f\u6574\u6570\u306e\u5e38\u8b58\u306b\u5f93\u3063\u305f\u5927\u5c0f\u6bd4\u8f03\u3092\u3057\u3066\u3044\u307e\u3059\u3002\u3067\u3082\u3001\u3053\u308c\u306f\u7686\u3055\u3093\u306e\u597d\u304d\u306b\u3067\u304d\u308b<span>Java<\/span>\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u3067\u3059\u306e\u3067\u3001\u3044\u304b\u3088\u3046\u306b\u3082\u5927\u5c0f\u6bd4\u8f03\u306e\u30eb\u30fc\u30eb\u3092\u81ea\u5206\u3067\u8a2d\u5b9a\u3067\u304d\u308b\u306e\u3067\u3059<span>!! <\/span>\u5927\u5c0f\u6bd4\u8f03\u306e\u7d50\u679c\u3001\u6b63\u8ca0\u306e\u6574\u6570\u3068<span>0<\/span>\u306e\u3069\u308c\u304b\u3092\u623b\u3059\u3068\u3044\u3046\u30eb\u30fc\u30eb\u3092\u5b88\u308a\u3055\u3048\u3059\u308c\u3070\u3044\u3044\u306e\u3067\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u3001\u3053\u306e\u30af\u30e9\u30b9\u306e\u5927\u5c0f\u6bd4\u8f03\u7d50\u679c\u3092\u756a\u53f7\u306e\u300c\u964d\u9806\u300d\u3068\u3057\u305f\u3044\u306a\u3089\u3001\u5927\u5c0f\u6bd4\u8f03\u3067\u623b\u3059\u6574\u6570\u306e\u6b63\u8ca0\u3092\u9006\u8ee2\u3055\u305b\u308b\u3060\u3051\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\tpublic int compareTo(Object o) {\r\n\t\tUser u = (User) o;\r\n\r\n\t\t\/\/ \u5b9f\u614b\u304c\u3069\u3046\u3067\u3042\u308c\u3001\u5224\u65ad\u7d50\u679c\u306f\u623b\u308a\u5024\u304c\u5168\u3066\r\n\t\t\/\/ \u76f8\u624b\u306e\u65b9\u304c\u5927\u304d\u3051\u308c\u3070\u3001\u81ea\u5206\u306e\u65b9\u304c\u300c\u5927\u304d\u3044(1)\u300d\u3068\u8fd4\u3059\r\n\t\tif (this.no &lt; u.no) {\r\n\t\t\treturn 1;\r\n\t\t}\r\n\r\n\t\t\/\/ \u6574\u6570\u306e\u964d\u9806\u306b\u3057\u305f\u3044\u306a\u3089\u3001\u76f8\u624b\u306e\u65b9\u304c\u5c0f\u3055\u3051\u308c\u3070\u3001\u81ea\u5206\u306e\u65b9\u304c\u300c\u5c0f\u3055\u3044(-1)\u300d\u3068\u8fd4\u3059\r\n\t\tif (this.no &gt; u.no) {\r\n\t\t\treturn -1;\r\n\t\t}\r\n\r\n\t\t\/\/ \u964d\u9806\u3067\u3082\u7b49\u3057\u3044\u3068\u3044\u3046\u3053\u3068\u306f\u5909\u308f\u3089\u306a\u3044\u306e\u3067\u30010\u3092\u8fd4\u3059\r\n\t\treturn 0;\r\n\t}<\/pre>\n<p>\u306a\u304a\u3001<span>Comparable<\/span>\u306e\u578b\u5f15\u6570<span>(&lt;&gt;<\/span>\u306e\u4e2d\u306b\u3042\u308b\u3082\u306e<span>)<\/span>\u3092\u304d\u3061\u3093\u3068\u4f7f\u3046\u306a\u3089\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308b\u3067\u3057\u3087\u3046<span>(<\/span>\u4ee5\u5f8c\u306f\u3053\u306e\u66f8\u304d\u65b9\u3067\u884c\u304d\u307e\u3059<span>)<\/span>\u3002<span>Java 1.5<\/span>\u4ee5\u964d\u3092\u4f7f\u308f\u308c\u3066\u3044\u308b\u306a\u3089\u3053\u3061\u3089\u304c\u304a\u52e7\u3081\u3067\u3059\u3002<\/p>\n<p>\u3057\u304b\u3057\u3001\u578b\u5f15\u6570\u3092\u4f7f\u3063\u305f\u3068\u3057\u3066\u3082\u3001\u884c\u3063\u3066\u3044\u308b\u3053\u3068\u306f\u672c\u8cea\u7684\u306b\u306f\u4f55\u3082\u5909\u308f\u3063\u3066\u3044\u307e\u305b\u3093\u3002\u578b\u5f15\u6570\u3092\u4f7f\u3046\u3053\u3068\u3067\u30ad\u30e3\u30b9\u30c8\u306e\u624b\u9593\u304c\u7701\u3051\u308b\u306e\u3068\u3001\u578b\u5f15\u6570\u3067\u6307\u5b9a\u3057\u305f\u30af\u30e9\u30b9\u4ee5\u5916\u3092<span>compareTo<\/span>\u306e\u5f15\u6570\u306b\u3059\u308b\u3068\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306a\u308b\u306e\u3067\u3001\u3088\u308a\u5b89\u5168\u6027\u304c\u9ad8\u307e\u3063\u305f\u3068\u3044\u3046\u304f\u3089\u3044\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class User implements Comparable&lt;User&gt; {\r\n\tint no = 0;\r\n\r\n\tUser(int no) {\r\n\t\tthis.no = no;\r\n\t}\r\n\r\n\tpublic int compareTo(User u) {\r\n\t\tif (this.no &lt; u.no) {\r\n\t\t\treturn -1;\r\n\t\t}\r\n\r\n\t\tif (this.no &gt; u.no) {\r\n\t\t\treturn 1;\r\n\t\t}\r\n\r\n\t\treturn 0;\r\n\t}\r\n}<\/pre>\n<h3><span id=\"i-3\">\uff13-\uff12\uff0e\u8907\u6570\u306e\u6761\u4ef6\u3067\u5927\u5c0f\u6bd4\u8f03\u3092\u3057\u305f\u3044\u5834\u5408<\/span><\/h3>\n<p>\u524d\u7bc0\u3067\u306f\u4e00\u3064\u306e\u9805\u76ee\u306e\u307f\u3067\u5927\u5c0f\u6bd4\u8f03\u3092\u3057\u3066\u307f\u307e\u3057\u305f\u3002\u5b9f\u969b\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u306f\u8907\u6570\u306e\u9805\u76ee\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u5927\u5c0f\u6bd4\u8f03\u3092\u3059\u308b\u3053\u3068\u304c\u591a\u3044\u306e\u3067\u3001\u305d\u306e\u3088\u3046\u306a\u3082\u306e\u3082\u5b9f\u88c5\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u4f8b\u3068\u3057\u3066\u3001\u5148\u307b\u3069\u306e\u30af\u30e9\u30b9<span>User<\/span>\u306b\u6c0f\u540d<span>(name)<\/span>\u3092\u8ffd\u52a0\u3057\u3066\u3001\u6c0f\u540d\u306e\u6607\u9806<span>\u2192<\/span>\u756a\u53f7\u306e\u964d\u9806\u3067\u5927\u5c0f\u6bd4\u8f03\u3092\u3059\u308b<span>compareTo<\/span>\u3092\u5b9f\u88c5\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">class User implements Comparable&lt;User&gt; {\r\n\tint no; \/\/ \u756a\u53f7\r\n\tString name; \/\/ \u6c0f\u540d\r\n\r\n\tUser(int no, String name) {\r\n\t\tthis.no = no;\r\n\t\tthis.name = name;\r\n\t}\r\n\r\n\tpublic int compareTo(User u) {\r\n\t\t\/\/ \u5148\u306b\u540d\u524d\u3067\u5927\u5c0f\u6bd4\u8f03\u3092\u3057\u3066\u2026\r\n\t\tint ret = this.name.compareTo(u.name);\r\n\r\n\t\t\/\/ \u540d\u524d\u3067\u5927\u5c0f\u306e\u9055\u3044\u304c\u3042\u308b\u306a\u3089\u305d\u3053\u3067\u7d42\u4e86\r\n\t\tif (ret != 0) {\r\n\t\t\treturn ret;\r\n\t\t}\r\n\r\n\t\t\/\/ \u540d\u524d\u304c\u540c\u3058\u306a\u3089\u756a\u53f7\u3067\u6bd4\u8f03(\u964d\u9806\u306a\u306e\u3067\u7b26\u53f7\u3092\u9006\u306b\u3059\u308b\u305f\u3081 -1 \u3092\u639b\u3051\u308b)\r\n\t\treturn Integer.compare(this.no, u.no) * -1;\r\n\t}\r\n\r\n\tpublic static void main(String[] args) {\r\n\t\tUser u1 = new User(1, \"\u5c71\u7530\u592a\u90ce\");\r\n\t\tUser u2 = new User(100, \"\u5c71\u7530\u592a\u90ce\"); \/\/ \u540c\u59d3\u540c\u540d!\r\n\r\n\t\tSystem.out.println(u1.compareTo(u2)); \/\/ \u2192 1!! \u540d\u524d\u304c\u540c\u3058\u306a\u306e\u3067\u756a\u53f7\u3067\u5224\u65ad\u30011\u3088\u308a100\u306e\u65b9\u304c\u5927\u304d\u3044\u304c\u3001\u964d\u9806\u306a\u306e\u3067\u300c1\u306e\u65b9\u304c100\u3088\u308a\u5927\u304d\u3044\u300d\r\n\t}\r\n}<\/pre>\n<p>\u6700\u521d\u306b\u3059\u3079\u304d\u306f\u540d\u524d\u306e\u5927\u5c0f\u6bd4\u8f03\u3067\u3059\u3002String\u306fComparable\u3067\u3059\u306e\u3067\u3001compareTo\u3092\u5b9f\u884c\u3067\u304d\u307e\u3059\u3002\u540d\u524d\u304c\u9055\u3048\u3070(!= 0)\u5927\u5c0f\u306f\u65e2\u306b\u78ba\u5b9a\u3057\u307e\u3057\u305f\u306e\u3067\u3001\u6bd4\u8f03\u7d50\u679c\u3067return\u3057\u307e\u3059\u3002<\/p>\n<p>\u540d\u524d\u306e\u5927\u5c0f\u6bd4\u8f03\u304c\u300c\u7b49\u3057\u3044\u300d\u306a\u3089\u3001\u3055\u3089\u306b\u756a\u53f7\u3067\u5927\u5c0f\u6bd4\u8f03\u3057\u307e\u3059\u3002<span>int<\/span>\u3067\u3042\u308b\u756a\u53f7\u306e<span>compareTo<\/span>\u306e\u7d50\u679c\u3092\u6b63\u8ca0\u53cd\u8ee2\u3055\u305b\u3066<span>return<\/span>\u3059\u308c\u3070\u3001\u756a\u53f7\u306e\u964d\u9806\u306e\u6bd4\u8f03\u7d50\u679c\u3092\u623b\u3059\u3053\u3068\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u3001\u6b63\u8ca0\u3092\u53cd\u8ee2\u3055\u305b\u308b\u305f\u3081\u306b<span>-1<\/span>\u3092\u639b\u3051\u308b\u306e\u306f\u3001<span>compareTo<\/span>\u3067\u306e\u5e38\u5957\u624b\u6bb5\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u3088\u3046\u306b\u3001\u8907\u6570\u306e\u9805\u76ee\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u5834\u5408\u306f\u3001<span>compareTo<\/span>\u306e\u4e2d\u3067\u4e00\u3064\u4e00\u3064\u306e\u9805\u76ee\u306e\u5927\u5c0f\u6bd4\u8f03\u3092\u884c\u3063\u3066\u7d50\u679c\u3092\u78ba\u8a8d\u3057\u306a\u304c\u3089\u3001\u5168\u4f53\u3068\u3057\u3066\u306e\u5927\u5c0f\u6bd4\u8f03\u3092\u884c\u3063\u3066\u3044\u3051\u3070\u3088\u3044\u306e\u3067\u3059\u3002<\/p>\n<h3><span id=\"-compare\">\uff13-\uff13\uff0e\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u5927\u5c0f\u6bd4\u8f03\u306f<span>compare<\/span>\u3067\u697d\u3057\u3088\u3046\uff01<\/span><\/h3>\n<p>\u5148\u307b\u3069Integer.compare(int, int)\u3068\u3044\u3046\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3044\u307e\u3057\u305f\u3002\u3053\u308c\u306f\u3001int\u540c\u58eb\u306e\u5927\u5c0f\u6bd4\u8f03\u3092compareTo\u306e\u65b9\u6cd5\u3067\u5b9f\u884c\u3057\u305f\u7d50\u679c\u3092\u8fd4\u3057\u3066\u304f\u308c\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002\u3067\u3059\u304b\u3089\u3001\u5b9f\u306f\u81ea\u5206\u3067\u308f\u3056\u308f\u3056if\u6587\u3092\u66f8\u304b\u306a\u304f\u3066\u3082\u3044\u3044\u306e\u3067\u3059\u3002\u697d\u3061\u3093\u3067\u3059\u306d\u3002<\/p>\n<p>Java 7\u4ee5\u964d\u3067\u306f\u3001\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u306b\u306f\u3053\u306e\u3088\u3046\u306a\u4fbf\u5229\u306a\u5927\u5c0f\u6bd4\u8f03\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308b\u306e\u3067\u3001\u3069\u3093\u3069\u3093\u6d3b\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u306ecompare\u30e1\u30bd\u30c3\u30c9\u4e00\u89a7\r\nByte.compare(byte, byte)\r\nShort.compare(short, short)\r\nInteger.compare(int, int)\r\nLong.compare(long, long)\r\nFloat.compare(float, float)\r\nDouble.compare(double, double)\r\nCharacter.compare(char, char)\r\nBoolean.compare(boolean, boolean)<\/pre>\n<h3><span id=\"-throw\">\uff13-\uff14\uff0e\u6bd4\u8f03\u3067\u304d\u306a\u3044\u306a\u3089\u4f8b\u5916\u3092<span>throw<\/span>\u3057\u3088\u3046<\/span><\/h3>\n<p>Comparable.compareTo\u306eJavadoc\u3092\u3088\u304f\u8aad\u3080\u3068\u3001\u4ee5\u4e0b\u306e\u8a18\u8ff0\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\u4f8b\u5916:\r\n\tNullPointerException - \u6307\u5b9a\u3055\u308c\u305f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cnull\u306e\u5834\u5408\r\n\tClassCastException - \u6307\u5b9a\u3055\u308c\u305f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u578b\u304c\u539f\u56e0\u3067\u3001\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u6bd4\u8f03\u3067\u304d\u306a\u3044\u5834\u5408<\/pre>\n<p>\u66f8\u3044\u3066\u3042\u308b\u306e\u306f\u3082\u3063\u3068\u3082\u306a\u3053\u3068\u3067\u3001\u5f15\u6570\u306e\u6bd4\u8f03\u5148\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c<span>null<\/span>\u306a\u3089\u6bd4\u8f03\u306e\u3057\u3088\u3046\u304c\u3042\u308a\u307e\u305b\u3093\u3057\u3001\u81ea\u5206\u3068\u95a2\u4fc2\u306e\u306a\u3044\u30af\u30e9\u30b9\u3068\u6bd4\u8f03\u3059\u308b\u3053\u3068\u306b\u3082\u610f\u5473\u304c\u3042\u308a\u307e\u305b\u3093\u306e\u3067\u3001\u305d\u3093\u306a\u5834\u5408\u306f\u4f8b\u5916\u3092<span>throw<\/span>\u3057\u3066\u300c\u6bd4\u8f03\u304c\u3067\u304d\u306a\u3044\u3088\u300d\u3068\u8868\u660e\u3057\u307e\u3059\u3002<\/p>\n<p>\u5148\u306e<span>User<\/span>\u306f\u81ea\u52d5\u7684\u306b\u305d\u3046\u306a\u308a\u307e\u3059\u304c\u3001\u304d\u3061\u3093\u3068\u660e\u793a\u7684\u306b\u30d7\u30ed\u30b0\u30e9\u30e0\u3059\u308b\u306a\u3089\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\tpublic int compareTo(Object o) {\r\n\t\t\/\/ \u6bd4\u8f03\u5148\u304cnull\u3067\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b\u3002\u203b\u3053\u306eif\u6587\u306fjava.util.Objects.requireNonNull(o)\u3067\u3082\u540c\u3058\r\n\t\tif (o == null) {\r\n\t\t\tthrow new NullPointerException();\r\n\t\t}\r\n\r\n\t\t\/\/ User\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3067\u3042\u308b\u304b\u78ba\u8a8d\u3059\u308b\r\n\t\tif (!(o instanceof User)) {\r\n\t\t\tthrow new ClassCastException();\r\n\t\t}\r\n\t\r\n\t\t\u2026\u4ee5\u4e0b\u540c\u69d8\u2026\r\n\t}\r\n}<\/pre>\n<h2><span id=\"JavaComparable\">\uff14\uff0e\u3010Java\u3011Comparable\u3092\u4f7f\u3063\u305f\u30bd\u30fc\u30c8<\/span><\/h2>\n<p>\u3055\u3066\u3001<span>Comparable.compareTo<\/span>\u304c\u3069\u3093\u306a\u3082\u306e\u304b\u3001\u3069\u3046\u30d7\u30ed\u30b0\u30e9\u30e0\u3059\u308c\u3070\u3044\u3044\u306e\u304b\u3092\u3054\u7406\u89e3\u3044\u305f\u3060\u3044\u305f\u3068\u3053\u308d\u3067\u3001\u5b9f\u969b\u306b<span>Comparable<\/span>\u306e\u30bd\u30fc\u30c8\u3092\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u3053\u3053\u3067\u306f<span>Comparable<\/span>\u306e\u30b5\u30f3\u30d7\u30eb\u3068\u3057\u3066\u3001\u5206\u304b\u308a\u3084\u3059\u3055\u304b\u3089<span>String<\/span>\u3092\u4f7f\u3044\u307e\u3059\u3002\u3067\u3082\u3001<span>Integer<\/span>\u3001<span>Date<\/span>\u3001<span>BigDecimal<\/span>\u3084\u3001\u3053\u306e\u8a18\u4e8b\u3067\u4f5c\u6210\u3057\u305f<span>User<\/span>\u306e\u3088\u3046\u306a<span>Comparable<\/span>\u3092\u5b9f\u88c5\u3057\u305f\u4efb\u610f\u306e\u30af\u30e9\u30b9\u3067\u3082\u540c\u3058\u3084\u308a\u65b9\u304c\u4f7f\u3048\u307e\u3059\u3002\u8981\u306f\u3001\u30bd\u30fc\u30c8\u5bfe\u8c61\u304c<span>Comparable<\/span>\u3067\u3055\u3048\u3042\u308c\u3070\u3044\u3044\u306e\u3067\u3059<span>!<\/span><\/p>\n<h3><span id=\"-ArrayssortObject\">\uff14-\uff11\uff0eArrays.sort(Object[])\u3067\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/span><\/h3>\n<p>Comparable\u306a\u3082\u306e\u306e\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3059\u308b\u306a\u3089\u3001Arrays.sort(Object[])\u3092\u4f7f\u3044\u307e\u3059\u3002\u5f15\u6570\u306fObject\u306e\u914d\u5217\u3067\u3059\u304c\u3001\u4e8b\u5b9f\u4e0aComparable\u304c\u5b9f\u88c5\u3055\u308c\u3066\u3044\u3066\u3001\u304b\u3064\u5168\u8981\u7d20\u304c\u540c\u3058\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3067\u306a\u3051\u308c\u3070\u3001\u5b9f\u884c\u6642\u306b\u4f8b\u5916\u304cthrow\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>Arrays.sort(Object[])\u306f\u300c\u5c0f\u3055\u3044\u300d\u9806\u306b\u30bd\u30fc\u30c8\u3057\u307e\u3059\u3002\u300c\u5927\u304d\u3044\u300d\u9806\u306b\u30bd\u30fc\u30c8\u3057\u305f\u3044\u5834\u5408\u306f\u5c11\u3057\u5de5\u592b\u304c\u5fc5\u8981\u3067\u3001Collections.reverseOrder()\u307e\u305f\u306fComparator.reverseOrder()\u3092\u4f75\u7528\u3057\u307e\u3059\u3002\u3082\u3061\u308d\u3093\u3001\u5c0f\u3055\u3044\u30fb\u5927\u304d\u3044\u306fComparable\u3067\u30d7\u30ed\u30b0\u30e9\u30e0\u3057\u305f\u3068\u304a\u308a\u306e\u9806\u5e8f\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u5f15\u6570\u3067\u4e0e\u3048\u305f\u914d\u5217\u81ea\u4f53\u306e\u4e26\u3073\u9806\u304c\u5909\u308f\u308a\u307e\u3059\u3002\u30bd\u30fc\u30c8\u3055\u308c\u305f\u914d\u5217\u3092\u623b\u308a\u5024\u3067\u53d7\u3051\u53d6\u308b\u30b9\u30bf\u30a4\u30eb\u3067\u306f\u306a\u3044\u306e\u3067\u3001\u6c17\u3092\u4ed8\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Arrays\u306eObject[]\u95a2\u9023\u30bd\u30fc\u30c8\u7528\u30e1\u30bd\u30c3\u30c9\u306e\u5b9a\u7fa9\r\npublic static void sort(Object[] a)\r\n\ta - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u914d\u5217\r\npublic static void sort(Object[] a, int fromIndex, int toIndex)\r\n\ta - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u914d\u5217\r\n\tfromIndex - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u6700\u521d\u306e\u8981\u7d20(\u3053\u308c\u3092\u542b\u3080)\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\r\n\ttoIndex - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u6700\u5f8c\u306e\u8981\u7d20(\u3053\u308c\u3092\u542b\u307e\u306a\u3044)\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\r\npublic static &lt;T&gt; void sort(T[] a, Comparator&lt;? super T&gt; c)\r\n\ta - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u914d\u5217\r\n\tc - \u914d\u5217\u306e\u9806\u5e8f\u3092\u6c7a\u5b9a\u3059\u308b\u30b3\u30f3\u30d1\u30ec\u30fc\u30bf\u3002 null\u5024\u306f\u3001\u8981\u7d20\u306e\u81ea\u7136\u9806\u5e8f\u4ed8\u3051\u304c\u4f7f\u7528\u3055\u308c\u308b\u3053\u3068\u3092\u793a\u3059\u3002\r\npublic static &lt;T&gt; void sort(T[] a, int fromIndex, int toIndex, Comparator&lt;? super T&gt; c)\r\n\ta - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u914d\u5217\r\n\tfromIndex - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u6700\u521d\u306e\u8981\u7d20(\u3053\u308c\u3092\u542b\u3080)\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\r\n\ttoIndex - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u6700\u5f8c\u306e\u8981\u7d20(\u3053\u308c\u3092\u542b\u307e\u306a\u3044)\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\r\n\tc - \u914d\u5217\u306e\u9806\u5e8f\u3092\u6c7a\u5b9a\u3059\u308b\u30b3\u30f3\u30d1\u30ec\u30fc\u30bf\u3002 null\u5024\u306f\u3001\u8981\u7d20\u306e\u81ea\u7136\u9806\u5e8f\u4ed8\u3051\u304c\u4f7f\u7528\u3055\u308c\u308b\u3053\u3068\u3092\u793a\u3059\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">String[] strings = { \"ABD\", \"ABB\", \"ABC\" };\r\n\r\nArrays.sort(strings); \/\/ \u300c\u5c0f\u3055\u3044\u300d\u9806(\u6b63\u9806)\u306b\u30bd\u30fc\u30c8\u3059\u308b\r\nSystem.out.println(Arrays.toString(strings)); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n\r\nArrays.sort(strings, Collections.reverseOrder()); \/\/ \u300c\u5927\u304d\u3044\u300d\u9806(\u9006\u9806)\u306b\u30bd\u30fc\u30c8\u3059\u308b\r\n\/* Arrays.sort(strings, Comparator.reverseOrder()); \/\/ \u3053\u308c\u3067\u3082\u540c\u3058 *\/\r\nSystem.out.println(Arrays.toString(strings)); \/\/ \u2192 ABD\u3001ABC\u3001ABB<\/pre>\n<p>\u958b\u59cb\u30fb\u7d42\u4e86\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306e\u5f15\u6570\u304c\u3042\u308b\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30bd\u30fc\u30c8\u3059\u308b\u7bc4\u56f2\u3092\u6307\u5b9a\u3067\u304d\u308b\u3082\u306e\u3067\u3059\u3002\u914d\u5217\u5168\u4f53\u3067\u306f\u306a\u304f\u3001\u90e8\u5206\u7684\u306b\u30bd\u30fc\u30c8\u3057\u305f\u3044\u5834\u5408\u306b\u4f7f\u3048\u307e\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">String[] strings = { \"987\", \"ABD\", \"ABB\", \"ABC\", \"123\" };\r\n\r\nArrays.sort(strings, 1, 4);\r\nSystem.out.println(Arrays.toString(strings)); \/\/ \u2192 987\u3001ABB\u3001ABC\u3001ABD\u3001123 (\u914d\u5217\u306estrings[1..3]\u304c\u30bd\u30fc\u30c8\u7bc4\u56f2)\r\n\r\nArrays.sort(strings, 1, 4, Collections.reverseOrder());\r\nSystem.out.println(Arrays.toString(strings)); \/\/ \u2192 987\u3001ABD\u3001ABC\u3001ABB\u3001123 (\u540c\u4e0a)<\/pre>\n<h3><span id=\"-CollectionssortListreverseListList\">\uff14-\uff12\uff0eCollections.sort(List)\/reverse(List)\u3067List\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/span><\/h3>\n<p>Comparable\u3092\u683c\u7d0d\u3057\u3066\u3044\u308bList\u3092\u30bd\u30fc\u30c8\u3059\u308b\u969b\u306f\u3001Collections.sort(List)\/reverse(List)\u304c\u4f7f\u3048\u307e\u3059\u3002\u9006\u9806\u306b\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u3089\u304b\u3058\u3081\u7528\u610f\u3055\u308c\u3066\u3044\u308b\u306e\u304c\u4fbf\u5229\u3067\u3059\u306d\u3002Arrays\u3068\u540c\u69d8\u306b\u5f15\u6570\u3067\u4e0e\u3048\u305fList\u81ea\u4f53\u306e\u4e26\u3073\u9806\u304c\u5909\u308f\u308a\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Collections\u306eList\u95a2\u9023\u30bd\u30fc\u30c8\u7528\u30e1\u30bd\u30c3\u30c9\u306e\u5b9a\u7fa9\r\npublic static &lt;T extends Comparable&lt;? super T&gt;&gt; void sort(List&lt;T&gt; list)\r\n\tlist - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u30ea\u30b9\u30c8\u3002\r\npublic static &lt;T&gt; void sort(List&lt;T&gt; list, Comparator&lt;? super T&gt; c)\r\n\tlist - \u30bd\u30fc\u30c8\u3055\u308c\u308b\u30ea\u30b9\u30c8\u3002\r\n\tc - \u30ea\u30b9\u30c8\u306e\u9806\u5e8f\u3092\u6c7a\u5b9a\u3059\u308b\u30b3\u30f3\u30d1\u30ec\u30fc\u30bf\u3002 null\u5024\u306f\u3001\u8981\u7d20\u306e\u81ea\u7136\u9806\u5e8f\u4ed8\u3051\u304c\u4f7f\u7528\u3055\u308c\u308b\u3053\u3068\u3092\u793a\u3059\u3002\r\npublic static void reverse(List&lt;?&gt; list)\r\n\tlist - \u8981\u7d20\u306e\u9806\u5e8f\u304c\u9006\u306b\u3055\u308c\u308b\u30ea\u30b9\u30c8\u3002<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">List&lt;String&gt; strings = Arrays.asList(\"ABD\", \"ABB\", \"ABC\");\r\n\r\nCollections.sort(strings); \/\/ \u300c\u5c0f\u3055\u3044\u300d\u9806(\u6b63\u9806)\u306b\u30bd\u30fc\u30c8\u3059\u308b\r\nSystem.out.println(strings); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n\r\nCollections.reverse(strings); \/\/ \u300c\u5927\u304d\u3044\u300d\u9806(\u9006\u9806)\u306b\u30bd\u30fc\u30c8\u3059\u308b\r\nSystem.out.println(strings); \/\/ \u2192 ABD\u3001ABC\u3001ABB<\/pre>\n<h3><span id=\"-StreamsortedStream\">\uff14-\uff13\uff0eStream.sorted()\u3067<span>Stream<\/span>\u306e\u7d50\u679c\u3092\u30bd\u30fc\u30c8\u3059\u308b<\/span><\/h3>\n<p>Stream\u306e\u4e2d\u9593\u64cd\u4f5c<span>sorted()<\/span>\u3092\u4f7f\u3063\u3066\u3082\u30bd\u30fc\u30c8\u304c\u3067\u304d\u307e\u3059\u3002\u9006\u9806\u306b\u3059\u308b\u5834\u5408\u306f\u3001Arrays\u3067\u3082\u51fa\u3066\u304d\u305fCollections.reverseOrder()\u3042\u308b\u3044\u306fComparator.reverseOrder()\u3092\u4f7f\u3044\u307e\u3059\u3002\u4ed6\u306e\u4e2d\u9593\u64cd\u4f5c\u3092\u884c\u3063\u305f\u7d50\u679c\u3092\u30bd\u30fc\u30c8\u3059\u308b\u3053\u3068\u3082\u671d\u98ef\u524d\u306a\u306e\u3067\u3001\u8272\u3005\u3068\u67d4\u8edf\u306b\u30bd\u30fc\u30c8\u3092\u884c\u3048\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Stream\u306e\u30bd\u30fc\u30c8\u7528\u30e1\u30bd\u30c3\u30c9\u306e\u5b9a\u7fa9\r\nStream&lt;T&gt; sorted()\r\nStream&lt;T&gt; sorted(Comparator&lt;? super T&gt; comparator)\r\n\tcomparator - \u30b9\u30c8\u30ea\u30fc\u30e0\u8981\u7d20\u306e\u6bd4\u8f03\u306b\u4f7f\u7528\u3055\u308c\u308b\u3001\u975e\u5e72\u6e09\u3067\u30b9\u30c6\u30fc\u30c8\u30ec\u30b9\u306aComparator<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">List&lt;String&gt; strings = Arrays.asList(\"ABD\", \"ABB\", \"ABC\");\r\n\r\n\/\/ \u300c\u5c0f\u3055\u3044\u300d\u9806(\u6b63\u9806)\u306b\u30bd\u30fc\u30c8\u3057\u3066\u3001\u5185\u5bb9\u3092\u51fa\u529b\u3057\u3066\u307f\u308b\r\nstrings.stream().sorted().forEach(System.out::println); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n\r\n\/\/ \u300c\u5927\u304d\u3044\u300d\u9806(\u9006\u9806)\u306b\u30bd\u30fc\u30c8\u3057\u3066\u3001\u5185\u5bb9\u3092\u51fa\u529b\u3057\u3066\u307f\u308b\r\nstrings.stream().sorted(Collections.reverseOrder()).forEach(System.out::println); \/\/ \u2192 ABD\u3001ABC\u3001ABB\r\n\/* strings.stream().sorted(Comparator.reverseOrder()).forEach(System.out::println); \/\/ \u3053\u308c\u3082\u3084\u3063\u3066\u3044\u308b\u3053\u3068\u306f\u540c\u3058 *\/<\/pre>\n<h3><span id=\"-TreeSetTreeMap\">\uff14-\uff14\uff0eTreeSet\/TreeMap\u304b\u3089\u30bd\u30fc\u30c8\u6e08\u306e\u5024\/\u30ad\u30fc\u3092\u53d6\u5f97\u3059\u308b<\/span><\/h3>\n<p>TreeSet\u3068<span>TreeMap<\/span>\u306f\u5c11\u3057\u7279\u6b8a\u306a<span>Set<\/span>\u30fb<span>Map<\/span>\u3067\u3001\u5024\u30fb\u30ad\u30fc\u3092\u53d6\u308a\u51fa\u3059\u6642\u306f\u3001<span>Comparable<\/span>\u3067\u306e\u4e26\u3073\u9806\u306b\u3057\u3066\u304f\u308c\u307e\u3059\u3002<span>TreeSet<\/span>\u306f\u5024\u306e\u81ea\u52d5\u30bd\u30fc\u30c8\u6a5f\u80fd\u304c\u4ed8\u3044\u305f<span>Set<\/span>\u3001<span>TreeSet<\/span>\u306f\u30ad\u30fc\u306e\u81ea\u52d5\u30bd\u30fc\u30c8\u6a5f\u80fd\u304c\u4ed8\u3044\u305f<span>Map<\/span>\u3068\u3057\u3066\u899a\u3048\u3066\u304a\u3044\u3066\u3082\u3044\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Set&lt;String&gt; treeSet = new TreeSet&lt;&gt;();\r\ntreeSet.add(\"ABC\");\r\ntreeSet.add(\"ABB\");\r\ntreeSet.add(\"ABD\");\r\ntreeSet.add(\"ABB\"); \/\/ \u540c\u3058\u5024\u3092\u5165\u308c\u3066\u3044\u308b\u304c\u3001Set\u306a\u306e\u3067\u683c\u7d0d\u3055\u308c\u308b\u306e\u306f1\u3064\u3060\u3051\r\ntreeSet.add(\"ABC\"); \/\/ \u540c\u4e0a\r\ntreeSet.add(\"ABD\"); \/\/ \u540c\u4e0a\r\n\r\n\/\/ TreeSet\u3092\u7528\u3044\u308b\u969b\u306f\u3001\u30bd\u30fc\u30c8\u3055\u308c\u3066\u3044\u308b\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u308b\r\ntreeSet.forEach(System.out::println); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n\r\nIterator it = treeSet.iterator();\r\nwhile (it.hasNext()) {\r\n\tSystem.out.println(it.next()); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">Map&lt;String, String&gt; treeMap = new TreeMap&lt;&gt;();\r\ntreeMap.put(\"ABC\", \"\u3042\");\r\ntreeMap.put(\"ABB\", \"\u3044\");\r\ntreeMap.put(\"ABD\", \"\u3046\");\r\n\r\n\/\/ TreeMap\u306e\u30ad\u30fc\u3092\u7528\u3044\u308b\u6642\u306f\u3001\u30bd\u30fc\u30c8\u3055\u308c\u3066\u3044\u308b\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u308b\r\nSet&lt;String&gt; keys = treeMap.keySet();\r\nkeys.forEach(System.out::println); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n\r\nIterator&lt;String&gt; it = keys.iterator();\r\nwhile (it.hasNext()) {\r\n\tSystem.out.println(it.next()); \/\/ \u2192 ABB\u3001ABC\u3001ABD\r\n}<\/pre>\n<p>\u3053\u3053\u3067\u4e00\u3064\u6ce8\u610f\u4e8b\u9805\u3092\u3002<span>TreeSet<\/span>\u3068<span>TreeMap<\/span>\u3092\u4f7f\u3046\u6642\u306f\u3001<span>TreeSet<\/span>\u306b\u6295\u5165\u3059\u308b\u5024\u30fb<span>TreeSet<\/span>\u3067\u4f7f\u3046\u30ad\u30fc\u306b\u3064\u3044\u3066\u5236\u9650\u304c\u3042\u308a\u307e\u3059\u3002\u6bd4\u8f03\u3059\u308b<span>2<\/span>\u3064\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9<span>(e1<\/span>\u3001<span>e2)<\/span>\u306b\u5bfe\u3057\u3066\u300c<span>e1.equals(e2)<\/span>\u304c<span>true<\/span>\u306e\u5834\u5408\u306f\u3001<span>e1.compareTo(e2)<\/span>\u3082<span>0<\/span>\u3092\u623b\u3059\u300d\u3092\u6e80\u305f\u3055\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>\u3067\u3059\u306e\u3067\u3001<span>Java<\/span>\u306e\u6a19\u6e96<span>API<\/span>\u306b\u3042\u308b\u30af\u30e9\u30b9\u3092\u4f7f\u3046\u5206\u306b\u306f\u307b\u3068\u3093\u3069\u554f\u984c\u3042\u308a\u307e\u305b\u3093\u304c\u3001\u81ea\u4f5c\u306e<span>Comparable<\/span>\u3092\u4f7f\u3046\u5834\u5408\u306f\u3001\u5236\u9650\u3092\u6e80\u305f\u3057\u3066\u3044\u308b\u304b\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002\u6a19\u6e96\u30af\u30e9\u30b9\u3067\u306e\u4f8b\u5916\u306f\u3001\u4f8b\u3048\u3070<span>BigDecimal<\/span>\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u3088\u3046\u306b\u3001<span>Object.equals<\/span>\u3068<span>Comparable.compareTo<\/span>\u306e\u9593\u306b\u306f\u3001\u5b9f\u306f\u3061\u3087\u3063\u3068\u3057\u305f\u95a2\u4fc2\u304c\u3042\u3063\u305f\u308a\u3057\u307e\u3059\u3002\u3053\u308c\u306f\u300c\u81ea\u7136\u9806\u5e8f\u4ed8\u3051\u304c<span>equals<\/span>\u3068\u4e00\u8cab\u6027\u304c\u3042\u308b\u300d\u3068\u304b\u300c<span>compareTo<\/span>\u3067\u8ab2\u305b\u3089\u308c\u308b\u9806\u5e8f\u306f<span>equals<\/span>\u3068\u4e00\u81f4\u3057\u3066\u3044\u308b\u300d\u306a\u3069\u3068\u8a00\u308f\u308c\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u8a73\u7d30\u306f\u5ef6\u3079\u307e\u305b\u3093\u304c\u3001\u8208\u5473\u304c\u3042\u308c\u3070\u8abf\u3079\u3066\u307f\u308b\u3068\u3001\u7406\u89e3\u304c\u6df1\u307e\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n<h2><span id=\"Comparatorcompare\">\uff15\uff0e\u3010\u95a2\u9023\u3011Comparator.compare\u306e\u4f7f\u3044\u65b9<\/span><\/h2>\n<p>Comparable.compareTo\u3068\u95a2\u4fc2\u306e\u3042\u308b\u3082\u306e\u3068\u3057\u3066\u3001\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9Comparator\u306e\u30e1\u30bd\u30c3\u30c9compare\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u623b\u308a\u5024\u306e<span>int<\/span>\u306e\u610f\u5473\u306f<span>compareTo<\/span>\u3068\u540c\u3058\u3067\u3001\u6b63\u8ca0\u306e\u6574\u6570\u3068<span>0<\/span>\u306b\u3088\u308b\u5927\u5c0f\u6bd4\u8f03\u7d50\u679c\u3067\u3059\u3002\u305f\u3060\u3057\u3001<span>compareTo<\/span>\u304c\u81ea\u5206\u81ea\u8eab\u3068\u6bd4\u8f03\u5148\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u6bd4\u8f03\u3057\u3066\u3044\u305f\u306e\u306b\u5bfe\u3057\u3001<span>2<\/span>\u3064\u306e\u5f15\u6570\u540c\u58eb\u3092\u6bd4\u8f03\u3059\u308b\u306e\u304c\u7570\u306a\u308b\u3068\u3053\u308d\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Comparator.compare\u306e\u30e1\u30bd\u30c3\u30c9\u5b9a\u7fa9\r\nint compare(T o1, T o2)\r\n\to1 - \u6bd4\u8f03\u5bfe\u8c61\u306e\u6700\u521d\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3002\r\n\to2 - \u6bd4\u8f03\u5bfe\u8c61\u306e2\u756a\u76ee\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3002<\/pre>\n<p>Comparator\u306f\u3001\u30bd\u30fc\u30c8\u3057\u305f\u3044\u30af\u30e9\u30b9\u304b\u3089\u30bd\u30fc\u30c8\u306e\u30ed\u30b8\u30c3\u30af\u90e8\u5206\u3092\u5206\u96e2\u3059\u308b\u306e\u304c\u4e3b\u306a\u7528\u9014\u3067\u3057\u3087\u3046\u3002\u30bd\u30fc\u30c8\u3092\u884c\u3044\u305f\u3044\u30af\u30e9\u30b9\u306b<span>Comparator<\/span>\u3092\u660e\u793a\u7684\u306b\u5b9f\u88c5\u3059\u308b\u306e\u306f\u898b\u304b\u3051\u307e\u305b\u3093\u3057\u3001\u610f\u5473\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u4f7f\u3044\u65b9\u3082\u7121\u540d\u30af\u30e9\u30b9\u3084\u30e9\u30e0\u30c0\u5f0f\u3067\u7528\u3044\u3089\u308c\u308b\u30b1\u30fc\u30b9\u3082\u591a\u3044\u3088\u3046\u306b\u611f\u3058\u307e\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3057\u3066\u4f7f\u3044\u307e\u3059\u3002<span>Comparator<\/span>\u306b\u30bd\u30fc\u30c8\u306e\u30ed\u30b8\u30c3\u30af\u90e8\u5206\u3092\u5206\u96e2\u3059\u308b\u3053\u3068\u3067\u3001\u81ea\u7531\u306b\u30bd\u30fc\u30c8\u306e\u30ed\u30b8\u30c3\u30af\u3092\u5207\u308a\u66ff\u3048\u3089\u308c\u308b\u306e\u3067\u3059\u3002\u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u30bd\u30fc\u30c8\u30ed\u30b8\u30c3\u30af\u306f<span>Comparable.compareTo<\/span>\u3067\u5b9f\u88c5\u3057\u3066\u3001\u305d\u306e\u4ed6\u306e\u7279\u6b8a\u30b1\u30fc\u30b9\u306f<span>Comparator<\/span>\u3068\u5f79\u5272\u5206\u62c5\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Comparator\u3092\u4f7f\u3048\u3070\u3001\u30bd\u30fc\u30c8\u306e\u30ed\u30b8\u30c3\u30af\u90e8\u5206\u3092\u81ea\u7531\u306b\u5207\u308a\u66ff\u3048\u3089\u308c\u308b\r\nComparator&lt;User&gt; c1 = new Comparator()&lt;&gt; {\r\n\tpublic int compare(User o1, User o2) {\r\n\t\treturn Integer.compare(o1.no, o2.no); \/\/ \u5927\u5c0f\u6bd4\u8f03\u306e\u30ed\u30b8\u30c3\u30af\u90e8\u5206\u306f\u81ea\u7531\u306b\u8a18\u8ff0\u3059\u308b\r\n\t}\r\n}\r\n\r\n\/\/ Comparator\u3092\u5358\u7d14\u306b\u9006\u9806\u306b\u3059\u308b\u3060\u3051\u306a\u3089\u3001Collections.reverseOrder(Comparator)\u3092\u4f7f\u3046\u3068\u697d\u3061\u3093!!\r\nComparator&lt;User&gt; c2 = Collections.reverseOrder(c1);\r\n\r\nList&lt;User&gt; users = ...;\r\nCollections.sort(users, c1); \/\/ \u756a\u53f7\u6607\u9806\u3067\u306e\u30bd\u30fc\u30c8\r\nCollections.sort(users, c2); \/\/ \u756a\u53f7\u964d\u9806\u3067\u306e\u30bd\u30fc\u30c8<\/pre>\n<h2><span id=\"JavaAPIcompareTo\">\uff16\uff0e\u3010\u53c2\u8003\u3011<span>Java<\/span>\u6a19\u6e96<span>API<\/span>\u306e\u30af\u30e9\u30b9\u3067\u306e<span>compareTo<\/span>\u306b\u3064\u3044\u3066<\/span><\/h2>\n<p>Java\u306e\u6a19\u6e96<span>API<\/span>\u306b\u3042\u308b\u3001\u826f\u304f\u4f7f\u308f\u308c\u308b\u30af\u30e9\u30b9\u3067\u306f\u3069\u3046\u3044\u3046\u57fa\u6e96\u3067\u5927\u5c0f\u6bd4\u8f03\u3055\u308c\u308b\u306e\u304b\u3092\u7c21\u5358\u306b\u307e\u3068\u3081\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u30af\u30e9\u30b9\u306f\u5168\u3066<span>Comparable<\/span>\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308b\u306e\u3067\u3001\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b<span>(=<\/span>\u30bd\u30fc\u30c8\u3067\u304d\u308b<span>)<\/span>\u306e\u3067\u3059\u3002<\/p>\n<ul>\n<li>Byte\/Short\/Integer\/Long\uff1a\u4fdd\u6301\u3059\u308b\u6574\u6570\u306e\u5927\u5c0f<\/li>\n<li>Float\/Double\uff1a\u4fdd\u6301\u3059\u308b\u5c0f\u6570\u70b9\u4ed8\u304d\u6570\u5024\u306e\u5927\u5c0f<\/li>\n<li>BigDecimal\/BigInteger\uff1a\u4fdd\u6301\u3059\u308b\u6570\u5024\u306e\u5927\u5c0f<\/li>\n<li>Boolean\uff1a<span>false<\/span>\u306f<span>true<\/span>\u3088\u308a\u3082\u5c0f\u3055\u3044\u3068\u5224\u65ad\u3055\u308c\u308b<\/li>\n<li>Character\uff1a\u4fdd\u6301\u3059\u308b\u6587\u5b57\u306e<span>Unicode<\/span>\u30b3\u30fc\u30c9\u30dd\u30a4\u30f3\u30c8\u306e\u6570\u5024\u306e\u5927\u5c0f<\/li>\n<li>String\uff1a\u4fdd\u6301\u3059\u308b\u6587\u5b57\u5217\u5168\u4f53\u306b\u5bfe\u3057\u3066\u3001\u5148\u982d\u306e\u6587\u5b57\u304b\u3089<span>Character<\/span>\u306e\u30ed\u30b8\u30c3\u30af\u3092\u7528\u3044\u3066\u5927\u5c0f\u6bd4\u8f03\u3059\u308b<span>(<\/span>\u8f9e\u66f8\u9806<span>)<\/span><\/li>\n<li>Date\/Calendar\/LocalDate\/LocalDateTime\u7b49\uff1a\u4fdd\u6301\u3059\u308b\u65e5\u4ed8\u30fb\u65e5\u6642\u304c\u30ab\u30ec\u30f3\u30c0\u30fc\u7684\u306b\u904e\u53bb\u306a\u3089\u5c0f\u3055\u3044\u3001\u672a\u6765\u306a\u3089\u5927\u304d\u3044<\/li>\n<li>Enum\uff1a\u5b9a\u6570\u3068\u3057\u3066\u5ba3\u8a00\u3055\u308c\u305f\u9806\u5e8f\u5024<span>(ordinal()<\/span>\u3067\u5f97\u3089\u308c\u308b\u6574\u6570\u5024<span>)<\/span>\u306e\u5927\u5c0f\u3067\u5224\u65ad<\/li>\n<\/ul>\n<p>\u6570\u5024\u306e\u30af\u30e9\u30b9\u306f\u6570\u5b57\u306e\u5927\u5c0f\u3001\u65e5\u4ed8\u30fb\u65e5\u6642\u306f\u65e9\u3044\u9806\u3067\u306e\u5224\u65ad\u306b\u306a\u308a\u307e\u3059\u3002<span>Boolean<\/span>\u306f\u7279\u5fb4\u7684\u306a\u306e\u3067\u3001\u305c\u3072\u899a\u3048\u3066\u304a\u304d\u307e\u3057\u3087\u3046\u3002<span>Enum<\/span>\u306e<span>compareTo<\/span>\u306f\u4f7f\u3046\u7b87\u6240\u306f\u5c11\u306a\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u306d\u3002<\/p>\n<p>\u6587\u5b57\u3084\u6587\u5b57\u5217\u306f\u3001\u3044\u308f\u3086\u308b\u300c\u8f9e\u66f8\u9806\u300d\u3067\u306e\u6bd4\u8f03\u304c\u884c\u308f\u308c\u307e\u3059\u3002\u76f4\u611f\u7684\u306b\u306f\u30a2\u30eb\u30d5\u30a1\u30d9\u30c3\u30c8\u9806\u306a\u3069\u306e\u4e26\u3073\u9806\u3060\u3068\u601d\u3063\u3066\u3082\u3089\u3063\u3066\u3082\u3001\u5b9f\u7528\u4e0a\u306f\u69cb\u3044\u307e\u305b\u3093\u3002\u5b9f\u969b\u306b\u306f\u3001\u305d\u308c\u305e\u308c\u306e\u6587\u5b57\u306b\u5272\u308a\u5f53\u3066\u3089\u308c\u3066\u3044\u308b<span>Unicode<\/span>\u30b3\u30fc\u30c9\u30dd\u30a4\u30f3\u30c8\u3068\u3044\u3046\u6570\u5024\u3067\u306e\u6bd4\u8f03\u3067\u3059\u3002\u6587\u5b57\u30fb\u6587\u5b57\u5217\u306f\u672c\u8cea\u7684\u306b\u306f\u6570\u5024\u306e\u96c6\u307e\u308a\u3060\u304b\u3089\u3067\u3059\u3002<\/p>\n<h3><span id=\"-Date\">\uff16-\uff11\uff0eDate\u306f\u30df\u30ea\u79d2\u307e\u3067\u306e\u6642\u9593\u3092\u6301\u3063\u3066\u3044\u308b<\/span><\/h3>\n<p>Date\u3084<span>Calendar<\/span>\u306f\u30df\u30ea\u79d2\u3067\u6642\u9593\u3092\u4fdd\u6301\u3057\u3066\u3044\u308b\u306e\u3067\u3001<span>compareTo<\/span>\u3067\u306f\u30df\u30ea\u79d2\u307e\u3067\u304c\u5927\u5c0f\u6bd4\u8f03\u306b\u53cd\u6620\u3055\u308c\u307e\u3059\u3002<span>Date<\/span>\u3092\u65e5\u4ed8\u3068\u3057\u3066\u6271\u3046\u306a\u3089\u3001<span>compareTo<\/span>\u3059\u308b\u524d\u306b\u6642\u9593\u4ee5\u4e0b\u3092<span>0<\/span>\u3067\u30af\u30ea\u30a2\u3057\u306a\u3044\u3068\u6b63\u3057\u304f\u5927\u5c0f\u6bd4\u8f03\u3055\u308c\u307e\u305b\u3093\u3002<\/p>\n<p>\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u6642\u9593\u4ee5\u4e0b\u3092<span>0<\/span>\u306b\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3092\u4f5c\u3063\u3066\u304a\u3044\u3066\u3082\u3044\u3044\u3067\u3057\u3087\u3046\u3002\u305f\u3060\u3001<span>Java 7<\/span>\u304b\u3089\u306e<span>LocalDateTime\/ZonedDateTime<\/span>\u306a\u3069\u306b\u306f\u3053\u306e\u3088\u3046\u306a\u6a5f\u80fd\u304c\u6a19\u6e96\u3067\u3042\u308a\u307e\u3059\u3057<span>(truncateTo)<\/span>\u3001\u65e5\u4ed8\u3060\u3051\u3092\u6301\u3064\u30af\u30e9\u30b9\u3082\u3042\u308b\u306e\u3067<span>(LocalDate)<\/span>\u3001\u65b0\u3057\u3044\u30d7\u30ed\u30b0\u30e9\u30e0\u306a\u3089\u305d\u3061\u3089\u3092\u4f7f\u3046\u306e\u304c\u304a\u52e7\u3081\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ Date\u306e\u6642\u9593\u4ee5\u4e0b\u30920\u306b\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u306e\u4f8b\r\n\/\/ case\u3092\u8ffd\u52a0\u3059\u308c\u3070\u3001\u6708\u30fb\u65e5\u306b\u3082\u5bfe\u5fdc\u53ef\u80fd\r\nstatic Date truncate(Date date, int fieldType) {\r\n\tCalendar cal = Calendar.getInstance();\r\n\tcal.setTime(date);\r\n\r\n\tswitch (fieldType) {\r\n\t\tcase Calendar.HOUR_OF_DAY:\r\n\t\t\tcal.set(Calendar.HOUR_OF_DAY, 0);\r\n\t\tcase Calendar.MINUTE:\r\n\t\t\tcal.set(Calendar.MINUTE, 0);\r\n\t\tcase Calendar.SECOND:\r\n\t\t\tcal.set(Calendar.SECOND, 0);\r\n\t\tcase Calendar.MILLISECOND:\r\n\t\t\tcal.set(Calendar.MILLISECOND, 0);\r\n\t\tdefault:\r\n\t\t\tthrow new IllegalArgumentException();\r\n\t}\r\n\r\n\treturn new Date(cal.getTimeInMillis());\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u4f7f\u7528\u4f8b\r\nSimpleDateFormat sdf = new SimpleDateFormat(\"yyyy\/MM\/dd HH:mm:ss.SSS\");\r\nDate date = new Date();\r\nSystem.out.println(sdf.format(date)); \/\/ \u2192 2018\/11\/07 12:34:56.789\r\n\r\nDate ymd = truncate(date, Calendar.HOUR_OF_DAY);\r\n\/\/ Date hour = truncate(date, Calendar.MINUTE);\r\n\/\/ Date minute = truncate(date, Calendar.SECOND);\r\n\/\/ Date second = truncate(date, Calendar.MILLISECOND);\r\n\r\nSystem.out.println(sdf.format(ymd)); \/\/ \u2192 2018\/11\/07 00:00:00.000<\/pre>\n<h3><span id=\"-BigDecimalcompareTo\">\uff16-\uff12\uff0eBigDecimal\u306e<span>compareTo<\/span>\u306f\u7cbe\u5ea6\u3092\u610f\u8b58\u3057\u306a\u3044<\/span><\/h3>\n<p>BigDecimal\u306f\u3001\u4fdd\u6301\u3059\u308b\u6570\u5b57\u306e\u8868\u73fe\u304c\u8907\u6570\u3042\u308a\u307e\u3059\u3002\u7279\u306b\u5c0f\u6570\u70b9\u4ee5\u4e0b\u306e\u7cbe\u5ea6\u304c\u9055\u3046\u30b1\u30fc\u30b9\u304c\u3042\u308a\u307e\u3059\u3002\u3067\u3082<span>compareTo<\/span>\u306e\u5834\u5408\u306f\u5358\u7d14\u306b\u6570\u5024\u3068\u3057\u3066\u306e\u5927\u5c0f\u30fb\u7b49\u3057\u3044\u304b\u3069\u3046\u304b\u304c\u5224\u65ad\u3055\u308c\u307e\u3059\u3002<span>equals<\/span>\u4ee3\u308f\u308a\u306b<span>compareTo<\/span>\u3092\u4f7f\u304a\u3046\u3068\u3059\u308b\u3068\u3001\u7d50\u679c\u304c\u9055\u3046\u3053\u3068\u304c\u3042\u308b\u306e\u3067\u8981\u6ce8\u610f\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">BigDecimal bd1 = new BigDecimal(\"1.0\"); \/\/ \u7cbe\u5ea6\u304c\u5c0f\u6570\u70b9\u4ee5\u4e0b1\u6841\u306e1\r\nBigDecimal bd2 = new BigDecimal(\"1.000\"); \/\/ \u7cbe\u5ea6\u304c\u5c0f\u6570\u70b9\u4ee5\u4e0b3\u6841\u306e1\r\n\r\nSystem.out.println(bd1.compareTo(bd2)); \/\/ \u2192 0\u306a\u306e\u3067\u7b49\u3057\u3044\u3053\u3068\u306b\u306a\u3063\u3066\u3044\u308b\r\nSystem.out.println(bd1.equals(bd2)); \/\/ \u2192 false\u3001\u7cbe\u5ea6\u304c\u9055\u3046\u305f\u3081\u3001\u9055\u3046\u3082\u306e\u3068\u3055\u308c\u3066\u3044\u308b<\/pre>\n<h3><span id=\"i-4\">\uff16-\uff13\uff0e\u7b26\u53f7\u306a\u3057\u6574\u6570\u306e\u5927\u5c0f\u6bd4\u8f03\u306b\u306f\u5c02\u7528\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308b<\/span><\/h3>\n<p>Java 8\u304b\u3089\u3001\u6574\u6570\u306e\u7b26\u53f7\u3067\u4f7f\u3063\u3066\u3044\u308b<span>1<\/span>\u30d3\u30c3\u30c8\u3082\u6570\u5024\u306e\u7bc4\u56f2\u306b\u5165\u308c\u3066\u8a08\u7b97\u3059\u308b\u305f\u3081\u306e\u6a5f\u80fd\u8ffd\u52a0\u304c\u884c\u308f\u308c\u307e\u3057\u305f<span>(Unsigned Arithmetic Support)<\/span>\u3002\u305d\u306e\u6d41\u308c\u3067\u3001\u5927\u5c0f\u6bd4\u8f03\u3067\u3082\u6b63\u8ca0\u306e\u7b26\u53f7\u3092\u610f\u8b58\u305b\u305a\u306b\u5927\u5c0f\u3092\u6bd4\u8f03\u3057\u305f\u3044\u5834\u5408\u304c\u51fa\u3066\u6765\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u305d\u306e\u3088\u3046\u306a\u76ee\u7684\u306e\u305f\u3081\u306b\u3001<span>Byte\/Short\/Integer\/Long<\/span>\u306e\u6574\u6570\u578b\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u3078\u306f\u3001<span>compareUnsigned<\/span>\u304c\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">public static int compareUnsigned(byte x, byte y)\r\npublic static int compareUnsigned(short x, short y)\r\npublic static int compareUnsigned(int x, int y)\r\npublic static int compareUnsigned(long x, long y)<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">int i1 = Integer.MAX_VALUE;\r\nint i2 = Integer.MAX_VALUE + 1;\r\n\r\nSystem.out.println(Integer.toString(Integer.MAX_VALUE)); \/\/ \u2192 2147483647\r\nSystem.out.println(Integer.toString(i2)); \/\/ \u2192 -2147483648 (\u30de\u30a4\u30ca\u30b9)\r\nSystem.out.println(Integer.toUnsigedString(i2)); \/\/ \u2192 2147483648 (Integer.MAX_VALUE\u3092\u8d85\u3048\u3066\u3044\u308b!!)\r\n\r\nSystem.out.println(Integer.compare(i1, i2)); \/\/ \u2192 1\r\nSystem.out.println(Integer.compareUnsigned(i1, i2)); \/\/ \u2192 -1<\/pre>\n<h2><span id=\"i-5\">\uff17\uff0e\u307e\u3068\u3081<\/span><\/h2>\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001<span>Comparable.compareTo<\/span>\u306b\u3064\u3044\u3066\u304a\u4f1d\u3048\u3057\u3066\u304d\u307e\u3057\u305f\u3002<span>compareTo<\/span>\u306f<span>2<\/span>\u3064\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e\u9593\u306e\u5927\u5c0f\u6bd4\u8f03\u3092\u884c\u3044\u3001\u7d50\u679c\u3092\u5c0f\u3055\u3044\u30fb\u7b49\u3057\u3044\u30fb\u5927\u304d\u3044\u306e\u3044\u305a\u308c\u304b\u3067\u623b\u3059\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<p>\u66f8\u3044\u3066\u3057\u307e\u3046\u3068\u5358\u7d14\u306a\u3082\u306e\u3067\u3059\u304c\u3001<span>compareTo<\/span>\u306f<span>Java<\/span>\u306e\u30bd\u30fc\u30c8\u51e6\u7406\u306e\u6839\u5e79\u3092\u652f\u3048\u308b\u3068\u3066\u3082\u91cd\u8981\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002\u3055\u3089\u306b\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u9593\u306e\u540c\u4e00\u6027\u306b\u3082\u95a2\u4fc2\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3042\u3063\u305f\u308a\u3057\u307e\u3059\u3002\u7e01\u306e\u4e0b\u306e\u529b\u6301\u3061\u7684\u306a\u611f\u3058\u3067\u3059\u306d\u3002<\/p>\n<p>compareTo\u306e\u57fa\u672c\u3092\u3057\u3063\u304b\u308a\u3068\u8eab\u306b\u7740\u3051\u3066\u3001<span>Java<\/span>\u3067\u306e\u30bd\u30fc\u30c8\u51e6\u7406\u3092\u81ea\u7531\u81ea\u5728\u306b\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u3087\u3046\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Java\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9Comparable\u306e\u30e1\u30bd\u30c3\u30c9compareTo\u3067\u306f\u3001\u5927\u5c0f\u6bd4\u8f03\u3092\u884c\u3044\u307e\u3059\u3002\u3053\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3092\u5b9f\u88c5\u3057\u305f\u30af\u30e9\u30b9\u306f\u5927\u5c0f\u6bd4\u8f03\u304c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u3001\u7d50\u679c\u3001\u30bd\u30fc\u30c8\u3092\u884c\u3048\u308b\u3088\u3046\u306b\u306a\u308b\u306e\u3067\u3059\u3002 \u3069\u3093\u306a\u30d7\u30ed\u30b0\u30e9 [&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\/948"}],"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=948"}],"version-history":[{"count":8,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/948\/revisions"}],"predecessor-version":[{"id":5700,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/948\/revisions\/5700"}],"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=948"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/categories?post=948"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}