{"id":833,"date":"2018-10-28T12:00:54","date_gmt":"2018-10-28T03:00:54","guid":{"rendered":"https:\/\/www.bold.ne.jp\/engineer-club\/?p=833"},"modified":"2025-09-17T10:47:04","modified_gmt":"2025-09-17T01:47:04","slug":"java-switch","status":"publish","type":"post","link":"https:\/\/www.bold.ne.jp\/engineer-club\/java-switch","title":{"rendered":"Java\u306eswitch\u3068\u306f\uff1f\u6761\u4ef6\u5206\u5c90\u306e\u305f\u3081\u306e\u4f7f\u3044\u65b9\u3084if\u6587\u3068\u306e\u4f7f\u3044\u5206\u3051\u65b9"},"content":{"rendered":"<p>Java\u306e<span>switch<\/span>\u6587\u306f\u3001\u6761\u4ef6\u5206\u5c90\u306e\u69cb\u6587\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001\u307e\u305a\u306f<span>switch<\/span>\u6587\u306e\u69cb\u6587\u3068\u4f7f\u3044\u65b9\u306e\u57fa\u672c\u3092\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002<\/p>\n<p>\u306a\u304a\u3001\u5b9f\u969b\u306b<span>switch<\/span>\u3092\u4f7f\u3046\u969b\u306f\u3001\u540c\u3058\u6761\u4ef6\u5206\u5c90\u306e\u69cb\u6587\u3067\u3042\u308b<span>if<\/span>\u6587\u3068\u306e\u4f7f\u3044\u5206\u3051\u306b\u8ff7\u3046\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u305d\u308c\u306b\u3001\u9577\u3089\u304f\u4ed5\u69d8\u304c\u5909\u308f\u3089\u306a\u304b\u3063\u305f<span>switch<\/span>\u6587\u306b\u3001\u6700\u8fd1\u65b0\u3057\u3044\u4ed5\u69d8\u304c\u8ffd\u52a0\u3055\u308c\u308b\u6c17\u914d\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u3067\u3059\u306e\u3067\u3001\u3053\u306e\u8a18\u4e8b\u3067\u306f<strong>switch\/if\u6587\u306e\u4f7f\u3044\u5206\u3051\u306e\u8003\u3048\u65b9<\/strong>\u3068\u3001<strong>\u65b0\u3057\u3044switch\u6587\u306e\u59ff<\/strong>\u3082\u304a\u4f1d\u3048\u3057\u307e\u3059<span>!!<\/span><\/p>\n<div id=\"toc_container\" class=\"no_bullets\"><p class=\"toc_title\">\u76ee\u6b21<\/p><ul class=\"toc_list\"><li><a href=\"#Javaswitch\">\uff11\uff0e\u3010Java\u3011switch\u6587\u306e\u57fa\u672c<\/a><ul><li><a href=\"#-switch\">\uff11-\uff11\uff0eswitch\u6587\u306e\u69cb\u6587<\/a><\/li><li><a href=\"#-switch-2\">\uff11-\uff12\uff0eswitch\u6587\u3067\u4f7f\u3048\u308b\u578b<\/a><\/li><li><a href=\"#-casebreak\">\uff11-\uff13\uff0ecase\u3092\u4e2d\u65ad\u3059\u308bbreak\u3068\u30d5\u30a9\u30fc\u30eb\u30b9\u30eb\u30fc<\/a><\/li><li><a href=\"#-default\">\uff11-\uff14\uff0edefault\u306f\u305d\u306e\u4ed6\u306e\u5834\u5408\u306b\u4f7f\u3046<\/a><\/li><\/ul><\/li><li><a href=\"#Javaswitch-2\">\uff12\uff0e\u3010Java\u3011switch\u6587\u306e\u306f\u307e\u308a\u30dd\u30a4\u30f3\u30c8\u3068\u5bfe\u5fdc\u65b9\u6cd5<\/a><ul><li><a href=\"#-null\">\uff12-\uff11\uff0e\u5f0f\u3084\u5024\u306bnull\u306f\u4f7f\u3048\u306a\u3044<\/a><\/li><li><a href=\"#i\">\uff12-\uff12\uff0e\u6841\u306e\u5927\u304d\u306a\u6574\u6570\u3084\u6d6e\u52d5\u5c0f\u6570\u70b9\u6570\u306f\u4f7f\u3048\u306a\u3044<\/a><\/li><li><a href=\"#i-2\">\uff12-\uff13\uff0e\u901a\u5e38\u306e\u30af\u30e9\u30b9\u3084\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306f\u4f7f\u3048\u306a\u3044<\/a><\/li><li><a href=\"#-case\">\uff12-\uff14\uff0ecase\u306b\u306f\u540c\u3058\u5024\u3092\u6307\u5b9a\u3067\u304d\u306a\u3044<\/a><\/li><li><a href=\"#-switch-3\">\uff12-\uff15\uff0eswitch\u6587\u5185\u306e\u5909\u6570\u306e\u30b9\u30b3\u30fc\u30d7\u306f\u30d6\u30ed\u30c3\u30af\u5168\u4f53<\/a><\/li><li><a href=\"#-switch-4\">\uff12-\uff16\uff0eswitch\u5185\u3067\u5ba3\u8a00\u3057\u305f\u5909\u6570\u306f\u30d6\u30ed\u30c3\u30af\u306e\u5916\u3067\u306f\u4f7f\u3048\u306a\u3044<\/a><\/li><li><a href=\"#-switchbreakbreak\">\uff12-\uff17\uff0e\u30cd\u30b9\u30c8\u3057\u305fswitch\u304b\u3089break\u3059\u308b\u306b\u306f\u30e9\u30d9\u30eb\u4ed8\u304dbreak\u3092\u4f7f\u3046<\/a><\/li><li><a href=\"#-switch-5\">\uff12-\uff18\uff0eswitch\u3067\u51e6\u7406\u3057\u305f\u3044\u5024\u4ee5\u5916\u304c\u6765\u305f\u6642\u306e\u5bfe\u51e6\u65b9\u6cd5<\/a><\/li><\/ul><\/li><li><a href=\"#Javaswitchif\">\uff13\uff0e\u3010Java\u3011switch\u6587\u3068if\u6587\u3068\u306e\u4f7f\u3044\u5206\u3051\u306e\u5224\u65ad\u57fa\u6e96<\/a><\/li><li><a href=\"#JavaswitchJEP_325Switch_Expressions\">\uff14\uff0e\u3010Java\u3011switch\u306e\u672a\u6765\u3001JEP 325:Switch Expressions<\/a><\/li><li><a href=\"#i-3\">\uff15\uff0e\u307e\u3068\u3081<\/a><\/li><\/ul><\/div>\n<h2><span id=\"Javaswitch\">\uff11\uff0e\u3010Java\u3011switch\u6587\u306e\u57fa\u672c<\/span><\/h2>\n<h3><span id=\"-switch\">\uff11-\uff11\uff0eswitch\u6587\u306e\u69cb\u6587<\/span><\/h3>\n<p>switch\u6587\u306e\u57fa\u672c\u7684\u306a\u69cb\u6587\u306f\u4ee5\u4e0b\u306e\u3082\u306e\u3067\u3059\u3002<span>&#8220;switch&#8221; <\/span>\u306e\u5f8c\u306b\u3042\u308b<span> () <\/span>\u306b\u5224\u5b9a\u3057\u305f\u3044\u5024\u30fb\u5909\u6570\u3092\u6307\u5b9a\u3057\u3001<span>&#8220;case&#8221; <\/span>\u306e\u5f8c\u308d\u306b\u30de\u30c3\u30c1\u3055\u305b\u305f\u3044\u5024\u30fb\u6761\u4ef6\u3092\u6307\u5b9a\u3057\u3001\u5fc5\u8981\u306a\u3060\u3051\u7f85\u5217\u3057\u307e\u3059\u3002<span>case<\/span>\u306e\u5f8c\u308d\u306b\u306f<span>&#8220;:&#8221;<\/span>\u304c\u5fc5\u8981\u3067\u3059\u306e\u3067\u3001\u5fd8\u308c\u306a\u3044\u3088\u3046\u306b\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ncase \u50241:\r\n\t\u5f0f\u306e\u8a55\u4fa1\u7d50\u679c\u304c\u50241\u3068\u7b49\u3057\u3044\u5834\u5408\u306b\u5b9f\u884c\u3059\u308b\u51e6\u7406;\r\n\tbreak;\r\ncase \u50242:\r\n\t\uff5e\u50242\u3068\u7b49\u3057\u3044\u5834\u5408\u306b\u5b9f\u884c\u3059\u308b\u51e6\u7406;\r\n\t\/\/break\u306f\u306a\u304f\u3066\u3082\u826f\u3044;\r\ncase \u5024n:\r\n\t\uff5e\u5024n\u3068\u7b49\u3057\u3044\u5834\u5408\u306b\u5b9f\u884c\u3059\u308b\u51e6\u7406;\r\n\tbreak;\r\ndefault:\r\n\t\u5f0f\u304ccase\u306e\u3069\u306e\u5024\u3068\u3082\u7b49\u3057\u304f\u306a\u3044\u5834\u5408\u306b\u5b9f\u884c\u3059\u308b\u51e6\u7406;\r\n\tbreak;\r\n}<\/pre>\n<p>case\u306f\u5206\u5c90\u306b\u5fc5\u8981\u306a\u5206\u3060\u3051\u8a18\u8ff0\u3067\u304d\u307e\u3059\u3002<span>break<\/span>\u306f\u5fc5\u9808\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u304c\u3001<span>case<\/span>\u3054\u3068\u306b\u8a18\u8ff0\u3059\u308b\u3053\u3068\u304c\u666e\u901a\u3067\u3057\u3087\u3046<span>(break<\/span>\u306e\u4f7f\u3044\u65b9\u306f\u5f8c\u8ff0\u3057\u307e\u3059<span>)<\/span>\u3002<\/p>\n<p>\u5b9f\u969b\u306b\u826f\u304f\u898b\u3089\u308c\u308b<span>switch<\/span>\u6587\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u611f\u3058\u3067\u3059\u3002\u5f0f\u306e\u8a55\u4fa1\u7d50\u679c\u306f\u305d\u306e\u90fd\u5ea6\u5909\u5316\u3057\u3001\u5024\u306f\u56fa\u5b9a\u3068\u306a\u3063\u3066\u3044\u3066\u3001\u5225\u306e\u5834\u6240\u3067\u5ba3\u8a00\u3055\u308c\u3066\u3044\u308b\u5909\u6570\u3092\u53c2\u7167\u3059\u308b\u306e\u304c\u666e\u901a\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u3053\u306e\u3088\u3046\u306a\u51e6\u7406\u7d50\u679c\u306e\u5b9a\u6570\u304c\u3001\u540c\u4e00\u30af\u30e9\u30b9\u5185\u3042\u308b\u3044\u306f\u5225\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u3066\u2026\r\npublic static final int SUCCESS = 1;\r\npublic static final int FAIL = 2;\r\npublic static final int EXCEPTION = 3;\r\n\r\n\/\/ switch\u6587\u3067\u5224\u65ad\u3057\u305f\u3044\u5024\u306b\u5bfe\u3057\u3066\u3001\u5b9a\u6570\u3092\u30de\u30c3\u30c1\u30f3\u30b0\u3055\u305b\u308b\r\nint result = someProcess();\r\nswitch (result) {\r\ncase SUCCESS:\r\n\t\/\/ \u6b63\u5e38\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\ncase FAIL:\r\n\t\/\/ \u5931\u6557\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\ncase EXCEPTION:\r\n\t\/\/ \u30a8\u30e9\u30fc\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u307e\u305f\u306f\u3001\u3053\u306e\u3088\u3046\u306aenum\u304c\u3069\u3053\u304b\u306b\u3042\u308a\u2026\r\nenum ProcessResult {\r\n\tSUCCESS, FAIL, EXCEPTION;\r\n}\r\n\r\n\/\/ \u5909\u6570\u304c\u6307\u3059enum\u306e\u5b9f\u4f53\u306b\u5bfe\u3057\u3066switch\u3059\u308b\r\nProcessResult result = someProcess(); \/\/ enum\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u3069\u308c\u304b\u3092\u6307\u3059\r\nswitch (result) {\r\ncase SUCCESS:\r\n\t\/\/ \u6b63\u5e38\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\ncase FAIL:\r\n\t\/\/ \u5931\u6557\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\ncase EXCEPTION:\r\n\t\/\/ \u30a8\u30e9\u30fc\u6642\u306e\u51e6\u7406\r\n\tbreak;\r\n}<\/pre>\n<p>if\u6587\u3067\u8868\u73fe\u3059\u308b\u306a\u3089\u3001<span>if<\/span>\uff5e<span>else if<\/span>\uff5e<span>else<\/span>\u3068\u4f3c\u305f\u610f\u5473\u306b\u306a\u308a\u307e\u3059\u3002<span>switch<\/span>\u6587\u306f\u3001\u9577\u3044<span>else-if<\/span>\u306e\u6761\u4ef6\u3092<span>&#8220;==&#8221;<\/span>\u3044\u3089\u305a\u3067\u30b7\u30f3\u30d7\u30eb\u306b\u66f8\u3051\u308b\u306e\u304c\u826f\u3044\u3068\u3053\u308d\u3067\u3059\u306d\u3002\u307e\u305f\u3001<span>switch<\/span>\u6587\u5168\u4f53\u3067\u5f0f\u306e\u8a55\u4fa1\u304c<span>1<\/span>\u56de\u3067\u6e08\u3080\u306e\u304c\u3001<span>if<\/span>\u6587\u3068\u6bd4\u3079\u3066\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u9762\u3067\u3082\u512a\u308c\u308b\u3068\u3053\u308d\u3067\u3059\u3002<\/p>\n<h3><span id=\"-switch-2\">\uff11-\uff12\uff0eswitch\u6587\u3067\u4f7f\u3048\u308b\u578b<\/span><\/h3>\n<p>1\u3064\u306e<span>switch<\/span>\u6587\u3067\u6271\u3048\u308b\u578b\u306f\u3001\u4ee5\u4e0b\u306e\u3044\u305a\u308c\u304b<span>1<\/span>\u3064\u3060\u3051\u3067\u3059<span>(Java 10<\/span>\u6642\u70b9<span>)<\/span>\u3002\u8907\u6570\u306e\u578b\u3092\u6df7\u305c\u3066\u306f\u4f7f\u3048\u307e\u305b\u3093\u3002<span>long<\/span>\u3084\u6d6e\u52d5\u5c0f\u6570\u70b9\u6570<span>(float<\/span>\u3001<span>double)<\/span>\u304c\u4f7f\u3048\u306a\u3044\u3053\u3068\u306b\u3082\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002\u5b9f\u52d9\u4e0a\u3067\u306f<span>int\/String\/enum<\/span>\u304c\u591a\u3044\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n<ul>\n<li>char\u3001<span>byte<\/span>\u3001<span>short<\/span>\u3001<span>int<\/span>\u3001<span>enum(J2SE 5<\/span>\u4ee5\u964d<span>)<\/span>\u3001<span>String(Java 7<\/span>\u4ee5\u964d<span>)<\/span><\/li>\n<li>\u304a\u3088\u3073<span>switch<\/span>\u6587\u306b\u5bfe\u5fdc\u3059\u308b\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9<span>(Char<\/span>\u3001<span>Byte<\/span>\u3001<span>Short<\/span>\u3001<span>Integer)<\/span><\/li>\n<\/ul>\n<p>\u4f8b\u3068\u3057\u3066\u3001\u5f0f\u3068\u5024\u306b<span>int<\/span>\u3068<span>String<\/span>\u304c\u6df7\u5728\u3057\u3066\u3044\u308b\u4e0b\u8a18<span>switch<\/span>\u6587\u306f\u3001\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u3068\u306a\u3063\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int value = 1;\r\nswitch (value) { \/\/ \u5f0f\u306fint\u3067\u3042\u308b\r\ncase 1:\r\ncase \"String\": \/\/ int\u3092\u5f0f\u306b\u3057\u3066\u3044\u308bswitch\u3067\u3001\u5024\u3092String\u3068\u3057\u3066\u3044\u308b\u306e\u3067\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\r\n}<\/pre>\n<p>\u3055\u3089\u306b\u3001\u5f0f\u30fb\u5024\u306e\u4e21\u65b9\u3067<span>null<\/span>\u306f\u6271\u3048\u307e\u305b\u3093\u3002\u5024\u304c<span>null<\/span>\u3060\u3068\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306a\u308a\u307e\u3059\u3002\u5f0f\u304c<span>null<\/span>\u306e\u5834\u5408\u306f\u3001\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u3067\u306a\u304f\u5b9f\u884c\u6642\u30a8\u30e9\u30fc<span>(NullPointerException)<\/span>\u3068\u306a\u308a\u307e\u3059\u306e\u3067\u3001\u5b9f\u884c\u3059\u308b\u307e\u3067\u30a8\u30e9\u30fc\u3068\u306a\u308b\u3053\u3068\u304c\u5206\u304b\u3089\u305a\u767a\u898b\u3057\u3065\u3089\u3044\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">String s = \"ABC\";\r\nswitch (s) {\r\ncase null: \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc!! null\u306f\u6307\u5b9a\u3067\u304d\u306a\u3044\r\n\tbreak;\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">String s = null;\r\nswitch (s) { \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u3068\u306f\u306a\u3089\u306a\u3044\u304c\u3001\u5b9f\u884c\u6642\u306bNullPointerException\u304c\u767a\u751f\u3059\u308b\r\ncase \"A\":\r\n\tbreak;\r\n}<\/pre>\n<p>switch\u6587\u306e\u5024\u3067\u4f7f\u3048\u308b\u306e\u306f\u3001\u305d\u308c\u305e\u308c\u306e\u578b\u306e\u30ea\u30c6\u30e9\u30eb\u5024\u30fb\u5909\u6570\u30fb\u6f14\u7b97\u7d50\u679c\u3067\u3059\u3002\u3057\u304b\u3082\u5024\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u78ba\u5b9a\u3057\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u308a\u307e\u305b\u3093\u306e\u3067\u3001\u666e\u901a\u306f\u9759\u7684\u306b\u5ba3\u8a00\u3057\u305f\u5b9a\u6570\u3001\u3042\u308b\u3044\u306f\u5b9a\u6570\u306b\u5bfe\u3059\u308b\u9759\u7684\u306a\u6f14\u7b97\u7d50\u679c\u3092\u7528\u3044\u307e\u3059\u3002<span>enum<\/span>\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u5b9a\u6570\u6271\u3044\u306a\u306e\u3067\u3001\u305d\u306e\u307e\u307e\u6307\u5b9a\u3067\u304d\u307e\u3059\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u66f8\u304d\u65b9\u304c\u3067\u304d\u307e\u3059\u3002\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u304c\u8aad\u3093\u3060\u6642\u306b\u308f\u304b\u308a\u3084\u3059\u304f\u3059\u308b\u306e\u306b\u3082\u4f7f\u3048\u305f\u308a\u3057\u307e\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">String s = \"ABC\";\r\nswitch (s) {\r\ncase \"A\" + \"B\" + \"C\":\r\n\t\/\/ \u3053\u306eswitch\u6587\u3092\u5b9f\u884c\u3059\u308b\u3068\u3053\u3053\u306b\u6765\u308b\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\"A\" + \"B\" + \"C\"\u2192\"ABC\"\u3068\u306a\u308b\u305f\u3081\r\n\tbreak;\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">final x = 100;\r\nint i = 1000;\r\nswitch (i) {\r\nx * 10:\r\n\t\/\/ \u3053\u306eswitch\u6587\u3092\u5b9f\u884c\u3059\u308b\u3068\u3053\u3053\u306b\u6765\u308b\u3002\r\n\t\/\/ x\u306f100\u3060\u3068final\u3067\u78ba\u5b9a\u3057\u3066\u304a\u308a\u3001\u3055\u3089\u306b10\u3092\u639b\u3051\u308b\u30681000\u306b\u306a\u308b\u3053\u3068\u304c\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u70b9\u3067\u78ba\u5b9a\u3059\u308b\u305f\u3081\r\n\tbreak;\r\n}<\/pre>\n<p>\u5f0f\u3068\u5024\u304c\u7b49\u3057\u3044\u304b\u306e\u5224\u5b9a\u306f\u3001<span>String<\/span>\u306a\u3089<span>equals()<\/span>\u306e\u7d50\u679c\u3067\u3001\u305d\u308c\u3089\u4ee5\u5916<span>(<\/span>\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u542b\u3080<span>)<\/span>\u306a\u3089<span>==<\/span>\u306e\u7d50\u679c\u3067\u3059\u3002<\/p>\n<h3><span id=\"-casebreak\">\uff11-\uff13\uff0ecase\u3092\u4e2d\u65ad\u3059\u308b<span>break<\/span>\u3068\u30d5\u30a9\u30fc\u30eb\u30b9\u30eb\u30fc<\/span><\/h3>\n<p>break\u306f<span>for<\/span>\u6587\u3084<span>while<\/span>\u6587\u3067\u306e\u610f\u5473\u3068\u8fd1\u304f\u3001\u5b9f\u884c\u3057\u3066\u3044\u308b<span>case<\/span>\u53e5\u306e\u51e6\u7406\u3092\u305d\u3053\u3067\u6253\u3061\u5207\u308a\u3001<span>switch<\/span>\u6587\u3092\u629c\u3051\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ncase \u50241:\r\n\t\u65871;   \/\/ \u50241\u306b\u8a72\u5f53\u3059\u308b\u5834\u5408\u306f\u3053\u3053\u304b\u3089\u51e6\u7406\u958b\u59cb\r\n\tbreak; \/\/ \u3053\u3053\u3067switch\u3092\u629c\u3051\u308b\r\ncase \u50242:\r\n\t\u65872;   \/\/ \u50242\u306b\u8a72\u5f53\u3059\u308b\u5834\u5408\u306f\u3053\u3053\u304b\u3089\u51e6\u7406\u958b\u59cb\r\n\tbreak; \/\/ \u3053\u3053\u3067switch\u3092\u629c\u3051\u308b\r\ncase \u50243:\r\n\t\u65873;   \/\/ \u50243\u306b\u8a72\u5f53\u3059\u308b\u5834\u5408\u306f\u3053\u3053\u304b\u3089\u51e6\u7406\u958b\u59cb\r\n\tbreak; \/\/ \u3053\u3053\u3067switch\u3092\u629c\u3051\u308b\r\n}<\/pre>\n<p>case\u53e5\u306e\u4e2d\u306b<span>break<\/span>\u304c\u306a\u3044\u3068\u3001\u305d\u306e\u6b21\u306b\u3042\u308b<span>case<\/span>\u306b\u51e6\u7406\u306e\u6d41\u308c\u304c\u305d\u306e\u307e\u307e\u79fb\u308a\u307e\u3059\u3002\u3053\u308c\u3092\u30d5\u30a9\u30fc\u30eb\u30b9\u30eb\u30fc<span>(fall through)<\/span>\u3068\u8a00\u3044\u307e\u3059\u3002\u65e5\u672c\u8a9e\u306b\u76f4\u8a33\u3059\u308c\u3070\u300c\u901a\u308a\u629c\u3051\u3066\u843d\u3061\u308b\u300d\u3067\u3001\u305d\u306e\u307e\u307e\u4e0b\u3078\u3059\u3068\u30fc\u3093\u3068\u843d\u3061\u3066\u3044\u304f\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002\u3053\u308c\u304c<span>switch<\/span>\u6587\u306e\u5927\u304d\u306a\u7279\u5fb4\u306e\u4e00\u3064\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ncase \u50241:\r\n\t\u65871;\r\n\t\/\/break\u3092\u8a18\u8ff0\u3057\u3066\u3044\u306a\u3044!!\r\ncase \u50242:\r\n\t\u65872;\r\n\tbreak;\r\ncase \u50243:\r\n\t\u65873;\r\n\tbreak;\r\n}<\/pre>\n<p>\u3053\u306e\u4f8b\u3060\u3068\u3001\u5f0f\u304c\u5024<span>1<\/span>\u306b\u8a72\u5f53\u3059\u308b\u5834\u5408\u306f\u6587<span>1<\/span>\u304c\u5b9f\u884c\u3055\u308c\u305f\u5f8c\u3001\u5024<span>2<\/span>\u306e\u6587<span>2<\/span>\u304c\u305d\u306e\u307e\u307e\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002\u5024<span>2<\/span>\u3067<span>break<\/span>\u3057\u3066\u3044\u307e\u3059\u306e\u3067\u3001\u305d\u3053\u3067<span>switch<\/span>\u6587\u5168\u4f53\u304c\u7d42\u4e86\u3057\u307e\u3059\u3002\u3053\u308c\u306f\u3001\u7279\u5b9a\u306e\u5024\u306e\u6642\u3060\u3051\u5148\u306b\u8ffd\u52a0\u3067\u5b9f\u884c\u3057\u305f\u3044\u51e6\u7406\u304c\u3042\u308b\u5834\u5408\u306b\u4f7f\u3048\u307e\u3059\u3002<\/p>\n<p>\u306a\u304a\u3001<span>case<\/span>\u5185\u306b\u306f\u51e6\u7406\u3092\u66f8\u304b\u306a\u304f\u3066\u3082\u3044\u3044\u306e\u3067\u3001\u8907\u6570\u306e\u5024\u3067\u540c\u3058\u51e6\u7406\u3092\u5b9f\u884c\u3059\u308b\u3060\u3051\u306a\u3089\u3001\u4ee5\u4e0b\u306e\u66f8\u304d\u65b9\u3082\u3067\u304d\u307e\u3059\u3002\u3053\u308c\u306f<span>if<\/span>\u6587\u3067\u306e\u300c\u307e\u305f\u306f<span>(||)<\/span>\u300d\u3068\u4f3c\u3066\u3044\u307e\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ncase \u50241:\r\ncase \u50242:\r\n\t\u50241\u3068\u50242\u306e\u5171\u901a\u51e6\u7406;\r\n\tbreak;\r\ncase \u50243:\r\n\t\u65873;\r\n\tbreak;\r\n}<\/pre>\n<h3><span id=\"-default\">\uff11-\uff14\uff0edefault\u306f\u305d\u306e\u4ed6\u306e\u5834\u5408\u306b\u4f7f\u3046<\/span><\/h3>\n<p>default\u306f\u3001\u5168\u3066\u306e<span>case<\/span>\u306b\u8a72\u5f53\u3057\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\u3092\u66f8\u304f\u6642\u306b\u4f7f\u7528\u3057\u307e\u3059\u3002<span>if<\/span>\uff5e<span>else if<\/span>\uff5e<span>else<\/span>\u3067\u8a00\u3046\u3001\u6700\u5f8c\u306e<span>else<\/span>\u306b\u76f8\u5f53\u3059\u308b\u3082\u306e\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ncase \u50241:\r\n\t\u65871;\r\n\tbreak;\r\ncase \u50242:\r\n\t\u65872;\r\n\tbreak;\r\ndefault:\r\n\t\u65873;\r\n\tbreak;\r\n}<\/pre>\n<p>\u306a\u304a\u3001<span>default<\/span>\u306f<span>switch<\/span>\u6587\u306e\u3069\u3053\u306b\u51fa\u3066\u6765\u3066\u3082\u554f\u984c\u3042\u308a\u307e\u305b\u3093\u3002\u305d\u306e\u305f\u3081\u3001\u5fc5\u305a\u6700\u5f8c\u306b\u6765\u308b<span>if<\/span>\u6587\u306e<span>else<\/span>\u3068\u306f\u6271\u3044\u304c\u9055\u3044\u307e\u3059\u3002\u3067\u3059\u304c\u3001<span>default<\/span>\u306f<span>else<\/span>\u3068\u540c\u69d8\u306b\u3001<span>case<\/span>\u306e\u4e00\u756a\u6700\u5f8c\u306b\u7f6e\u304f\u3053\u3068\u304c\u666e\u901a\u3067\u3057\u3087\u3046\u3002<\/p>\n<p>\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e<span>switch<\/span>\u6587\u3082\u69cb\u6587\u4e0a\u306f\u6b63\u3057\u3044\u3082\u306e\u3067\u3059\u3002\u3053\u3053\u3067<span>default<\/span>\u3067\u306e<span>break<\/span>\u304c\u306a\u3044\u3068\u5f8c\u308d\u306e<span>case<\/span>\u304c\u30d5\u30a9\u30fc\u30eb\u30b9\u30eb\u30fc\u3067\u5b9f\u884c\u3055\u308c\u3066\u3057\u307e\u3044\u307e\u3059\u3002\u7279\u5225\u306a\u7406\u7531\u304c\u306a\u3051\u308c\u3070\u6700\u5f8c\u306b\u3057\u3066\u304a\u304f\u306e\u304c\u7121\u96e3\u3067\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">switch (\u5f0f) {\r\ndefault:\r\n\t\u65873;\r\n\tbreak; \/\/ \u3053\u306ebreak\u304c\u306a\u3044\u3068\u3001\u5f8c\u308d\u306ecase\u3078\u30d5\u30a9\u30fc\u30eb\u30b9\u30eb\u30fc\u3057\u3066\u3057\u307e\u3046\r\ncase \u50241:\r\n\t\u65871;\r\n\tbreak;\r\ncase \u50242:\r\n\t\u65872;\r\n\tbreak;\r\n}<\/pre>\n<h2><span id=\"Javaswitch-2\">\uff12\uff0e\u3010Java\u3011switch\u6587\u306e\u306f\u307e\u308a\u30dd\u30a4\u30f3\u30c8\u3068\u5bfe\u5fdc\u65b9\u6cd5<\/span><\/h2>\n<p>\u3053\u3053\u3067\u306f<span>switch<\/span>\u6587\u3067\u3088\u304f\u306f\u307e\u308b\u30dd\u30a4\u30f3\u30c8\u3068\u5bfe\u5fdc\u65b9\u6cd5\u3092\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002\u3082\u3057<span>switch<\/span>\u6587\u3067\u30c8\u30e9\u30d6\u30eb\u304c\u8d77\u304d\u305f\u3089\u3001\u4ee5\u4e0b\u306e\u3053\u3068\u306b\u8a72\u5f53\u3057\u306a\u3044\u304b\u8abf\u3079\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<h3><span id=\"-null\">\uff12-\uff11\uff0e\u5f0f\u3084\u5024\u306b<span>null<\/span>\u306f\u4f7f\u3048\u306a\u3044<\/span><\/h3>\n<p>\u524d\u8ff0\u306e\u3068\u304a\u308a\u3001<span>switch<\/span>\u6587\u306e\u5f0f\u3084\u5024\u306b<span>null<\/span>\u306f\u4f7f\u3048\u307e\u305b\u3093\u3002\u5b9f\u884c\u6642\u306b<span>switch<\/span>\u6587\u306b\u95a2\u4fc2\u3059\u308b\u7b87\u6240\u3067<span>NullPointerException<\/span>\u304c\u767a\u751f\u3057\u305f\u306a\u3089\u3001\u5f0f\u306b\u95a2\u4fc2\u3059\u308b\u5909\u6570\u304c\u6307\u3057\u3066\u3044\u308b\u3082\u306e\u304c<span>null<\/span>\u3067\u306a\u3044\u304b\u3092\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<h3><span id=\"i\">\uff12-\uff12\uff0e\u6841\u306e\u5927\u304d\u306a\u6574\u6570\u3084\u6d6e\u52d5\u5c0f\u6570\u70b9\u6570\u306f\u4f7f\u3048\u306a\u3044<\/span><\/h3>\n<p>\u3053\u308c\u3082\u524d\u8ff0\u306e\u3068\u304a\u308a\u3001\u5f0f\u3084\u5024\u306b<span>long<\/span>\u3084<span>float<\/span>\u3001<span>double(<\/span>\u304a\u3088\u3073\u305d\u308c\u3089\u306e\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u3067\u3042\u308b<span>Long<\/span>\u3001<span>Float<\/span>\u3001<span>Double)<\/span>\u306f\u4f7f\u3048\u307e\u305b\u3093\u3002\u6570\u5024\u3092\u8868\u73fe\u3059\u308b\u30af\u30e9\u30b9\u3067\u3042\u308b<span>Number<\/span>\u3084<span>BigInteger<\/span>\u3084<span>BigDecimal<\/span>\u3082\u540c\u69d8\u306b\u4f7f\u3048\u307e\u305b\u3093\u3002<\/p>\n<h3><span id=\"i-2\">\uff12-\uff13\uff0e\u901a\u5e38\u306e\u30af\u30e9\u30b9\u3084\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306f\u4f7f\u3048\u306a\u3044<\/span><\/h3>\n<p>switch\u3067\u4f7f\u3048\u308b\u4ee5\u5916\u306e\u578b\u3001\u3064\u307e\u308a\u81ea\u5206\u3067\u4f5c\u3063\u305f\u30af\u30e9\u30b9\u3084\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3067\u3082<span>switch<\/span>\u306f\u3067\u304d\u307e\u305b\u3093\u3002<\/p>\n<h3><span id=\"-case\">\uff12-\uff14\uff0ecase\u306b\u306f\u540c\u3058\u5024\u3092\u6307\u5b9a\u3067\u304d\u306a\u3044<\/span><\/h3>\n<p>case\u306b\u306f\u540c\u3058\u5024\u3092\u6307\u5b9a\u3067\u304d\u307e\u305b\u3093\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306e\u30e1\u30c3\u30bb\u30fc\u30b8\u3082\u307e\u3060\u308f\u304b\u308a\u3084\u3059\u3044\u306e\u3067\u3059\u3050\u5bfe\u5fdc\u3067\u304d\u308b\u3068\u601d\u3044\u307e\u3059\u304c\u3001\u5b9a\u6570\u3092\u7f85\u5217\u3057\u305f\u5834\u5408\u306b\u540c\u3058\u5024\u304c\u3042\u308b\u304b\u3069\u3046\u304b\u306f\u5206\u304b\u308a\u3065\u3089\u3044\u306e\u3067\u3001\u5b9a\u6570\u306e\u5b9a\u7fa9\u5143\u3092\u3057\u3063\u304b\u308a\u78ba\u8a8d\u3059\u308b\u3088\u3046\u306b\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc(\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u306f\"\u91cd\u8907 case\")\r\nint x = 0;\r\nswitch (x) {\r\n0:\r\n\tbreak;\r\n0:\r\n\tbreak;\r\n}<\/pre>\n<h3><span id=\"-switch-3\">\uff12-\uff15\uff0eswitch\u6587\u5185\u306e\u5909\u6570\u306e\u30b9\u30b3\u30fc\u30d7\u306f\u30d6\u30ed\u30c3\u30af\u5168\u4f53<\/span><\/h3>\n<p>\u3053\u308c\u306f\u7d50\u69cb\u3084\u3084\u3053\u3057\u3044\u3067\u3059\u3002\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e<span>switch<\/span>\u6587\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306a\u308a\u307e\u3059\u3002\u3067\u3059\u306e\u3067\u3001\u306a\u308b\u3079\u304f\u8907\u6570\u306e<span>case<\/span>\u306b\u307e\u305f\u304c\u308b\u3088\u3046\u306a\u5909\u6570\u306f\u4f7f\u308f\u305a\u3001\u306a\u308b\u3079\u304f\u4e00\u3064\u306e<span>case<\/span>\u306e\u4e2d\u306b\u53ce\u307e\u308b\u3088\u3046\u306b\u4f7f\u3046\u306e\u304c\u826f\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 1;\r\nswitch (x) {\r\ncase 0:\r\n\t\/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc!! \u3053\u306e\u6642\u70b9\u3067\u306f\u5909\u6570y\u304c\u5ba3\u8a00\u3055\u308c\u3066\u3044\u306a\u3044\r\n\tSystem.out.println(y);\r\ncase 10:\r\n\tint y = 0;\r\ncase 100:\r\n\t\/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc!! case 10\u306e\u5f8c\u306a\u306e\u3067\u5909\u6570y\u306f\u4f7f\u3048\u308b\u304c\u3001\u76f4\u63a5\u3053\u306ecase\u306b\u6765\u305f\u6642\u306f\u5909\u6570\u304c\u672a\u521d\u671f\u5316\u306a\u53ef\u80fd\u6027\u304c\u3042\u308b\r\n\tSystem.out.println(y);\r\n}<\/pre>\n<h3><span id=\"-switch-4\">\uff12-\uff16\uff0eswitch\u5185\u3067\u5ba3\u8a00\u3057\u305f\u5909\u6570\u306f\u30d6\u30ed\u30c3\u30af\u306e\u5916\u3067\u306f\u4f7f\u3048\u306a\u3044<\/span><\/h3>\n<p>for\/while\/if\u6587\u306a\u3069\u3068\u540c\u3058\u3067\u3001<span>switch<\/span>\u6587\u5168\u4f53\u304c\u5927\u304d\u306a\u4e00\u3064\u306e\u30d6\u30ed\u30c3\u30af\u306b\u306a\u308b\u306e\u3067\u3001<span>{}<\/span>\u306e\u4e2d\u3067\u5ba3\u8a00\u3057\u305f\u5909\u6570\u306f<span>switch<\/span>\u6587\u306e\u5916\u90e8\u3067\u306f\u4f7f\u3048\u307e\u305b\u3093\u3002\u898b\u843d\u3068\u3057\u304c\u3061\u306a\u306e\u3067\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 1;\r\n\r\nswitch (x) {\r\ncase 0:\r\n\tint x2 = 0;\r\n}\r\n\r\nSystem.out.println(x2); \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc!! x2\u306fswitch\u6587\u306e\u30d6\u30ed\u30c3\u30af\u306e\u4e2d\u3067\u306e\u307f\u6709\u52b9<\/pre>\n<h3><span id=\"-switchbreakbreak\">\uff12-\uff17\uff0e\u30cd\u30b9\u30c8\u3057\u305f<span>switch<\/span>\u304b\u3089<span>break<\/span>\u3059\u308b\u306b\u306f\u30e9\u30d9\u30eb\u4ed8\u304d<span>break<\/span>\u3092\u4f7f\u3046<\/span><\/h3>\n<p>\u3042\u307e\u308a\u306a\u3044\u3068\u601d\u3044\u307e\u3059\u304c\u3001<span>switch<\/span>\u6587\u3092\u30cd\u30b9\u30c8\u3055\u305b\u305f\u3044\u3053\u3068\u304c\u3042\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u305d\u306e\u5834\u5408\u3001\u30cd\u30b9\u30c8\u304c\u6df1\u3044\u65b9\u306e<span>switch<\/span>\u6587\u3092<span>break<\/span>\u3057\u305f\u3060\u3051\u3067\u306f\u3001\u305d\u306e<span>switch<\/span>\u6587\u3060\u3051\u304c<span>break<\/span>\u3055\u308c\u308b\u306e\u3067\u3001\u5927\u5143\u306e<span>switch<\/span>\u6587\u306e\u5f8c\u7d9a\u51e6\u7406\u306f\u305d\u306e\u307e\u307e\u5b9f\u884c\u3055\u308c\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 1;\r\nint y = 100;\r\n\r\nswitch (x) { \/\/ \u5927\u5143\u306eswitch\r\ncase 1:\r\n\tswitch (y) { \/\/ \u30cd\u30b9\u30c8\u3057\u305fswitch\r\n\tcase 100:\r\n\t\tbreak; \/\/ \u3053\u3053\u3067break\u3057\u3066\u3082\u3001\r\n\t}\r\n\tSystem.out.println(\"after switch(y)\"); \/\/ \u3053\u306e\u6587\u306f\u5b9f\u884c\u3055\u308c\u308b\r\n\tbreak;\r\n}<\/pre>\n<p>\u3082\u3057\u3001\u30cd\u30b9\u30c8\u304c\u6df1\u3044<span>switch<\/span>\u6587\u304b\u3089\u76f4\u63a5<span>switch<\/span>\u6587\u5168\u4f53\u3092<span>break<\/span>\u3057\u305f\u3044\u306a\u3089\u3001\u30e9\u30d9\u30eb\u4ed8\u304d<span>break<\/span>\u304c\u4f7f\u3048\u307e\u3059\u3002\u4f8b\u306f\u4ee5\u4e0b\u306e\u3068\u304a\u308a\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 1;\r\nint y = 100;\r\n\r\nSWITCH1: switch (x) {\r\ncase 1:\r\n\tswitch (y) {\r\n\tcase 100:\r\n\t\tbreak SWITCH1; \/\/ \u30e9\u30d9\u30eb\u4ed8\u304dbreak\u3057\u3066\u5927\u5143\u306eswitch\u6587\u5168\u4f53\u304b\u3089\u629c\u3051\u308c\u3070\u3001\r\n\t}\r\n\tSystem.out.println(\"after switch(y)\"); \/\/ \u3053\u306e\u6587\u306f\u5b9f\u884c\u3055\u308c\u306a\u3044\r\n\tbreak;\r\n}<\/pre>\n<h3><span id=\"-switch-5\">\uff12-\uff18\uff0eswitch\u3067\u51e6\u7406\u3057\u305f\u3044\u5024\u4ee5\u5916\u304c\u6765\u305f\u6642\u306e\u5bfe\u51e6\u65b9\u6cd5<\/span><\/h3>\n<p>switch\u3067\u51e6\u7406\u3057\u305f\u3044\u5024\u4ee5\u5916\u304c\u6765\u305f\u6642\u306e\u5bfe\u51e6\u65b9\u6cd5\u306b\u306f\u3044\u304f\u3064\u304b\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>1\u3064\u76ee\u306f\u305d\u3082\u305d\u3082\u5fc5\u8981\u306a\u5024\u4ee5\u5916\u3092<span>case<\/span>\u306b\u66f8\u304b\u306a\u3044\u304b\u3001\u65e2\u306b\u304a\u4f1d\u3048\u3057\u305f<span>default<\/span>\u3092\u4f7f\u3048\u3070\u826f\u3044\u3067\u3057\u3087\u3046\u3002<span>default<\/span>\u3092\u4f7f\u3046\u5834\u5408\u3082\u6307\u5b9a\u306f\u3059\u308b\u3051\u308c\u3069\u3082\u3001\u4e2d\u3067\u306f\u4f55\u3082\u3057\u306a\u3044\u306e\u3067\u3059\u3002\u4f55\u4e8b\u3082\u306a\u304b\u3063\u305f\u304b\u306e\u3054\u3068\u304f\u5f8c\u7d9a\u306e\u51e6\u7406\u304c\u52d5\u3051\u3070\u3044\u3044\u306a\u3089\u3053\u308c\u304c\u6700\u3082\u7c21\u5358\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 100;\r\n\r\nswtich(x) {\r\n10:\r\n\t10\u306e\u6642\u306e\u51e6\u7406;\r\n\tbreak;\r\n20:\r\n\t20\u306e\u6642\u306e\u51e6\u7406;\r\n\tbreak;\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">int x = 100;\r\n\r\nswtich(x) {\r\n10:\r\n\t10\u306e\u6642\u306e\u51e6\u7406;\r\n\tbreak;\r\n20:\r\n\t20\u306e\u6642\u306e\u51e6\u7406;\r\n\tbreak;\r\ndefault:\r\n\t\/\/ \u4f55\u3082\u3057\u306a\u3044\r\n}<\/pre>\n<p>2\u3064\u76ee\u306f\u3001<span>default<\/span>\u306f\u4f7f\u3046\u3051\u308c\u3069\u3082\u4f8b\u5916\u3092<span>throw<\/span>\u3059\u308b\u3082\u306e\u3067\u3059\u3002\u30a4\u30c7\u30a3\u30aa\u30e0\u306e\u4e00\u3064\u3067\u3082\u3042\u308a\u307e\u3059\u3002\u826f\u304f\u898b\u304b\u3051\u308b\u306e\u306f<span>IllegalArgumentException<\/span>\u3084<span>IllegalStateException<\/span>\u3092<span>throw<\/span>\u3059\u308b\u3082\u306e\u3067\u3059\u304c\u3001\u4ed6\u306e\u4f8b\u5916\u3084\u81ea\u4f5c\u306e\u4f8b\u5916\u3092<span>throw<\/span>\u3057\u3066\u3082<span>OK<\/span>\u3067\u3059\u3002<span>if-else<\/span>\u306e<span>else<\/span>\u3067\u4f8b\u5916\u3092<span>throw<\/span>\u3059\u308b\u306e\u3068\u540c\u3058\u3067\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int x = 100;\r\nint result;\r\n\r\nswtich(x) {\r\n10:\r\n\tresult = x * 10;\r\n\tbreak;\r\n20:\r\n\tresult = x * 100;\r\n\tbreak;\r\ndefault:\r\n\tthrow new IllegalStateException(); \/\/ 10, 20\u4ee5\u5916\u306e\u5024\u306a\u3089\u4f8b\u5916\u3092throw\u3059\u308b\r\n}\r\n\r\nSystem.out.println(result);<\/pre>\n<p>\u3053\u308c\u306e\u826f\u3044\u3068\u3053\u308d\u306f\u3001\u60f3\u5b9a\u3057\u305f\u5024\u4ee5\u5916\u3067\u306f\u7d76\u5bfe\u306b\u5f8c\u7d9a\u51e6\u7406\u304c\u52d5\u304b\u306a\u3044\u3053\u3068\u3067\u3059\u3002\u3053\u3046\u3044\u3046\u66f8\u304d\u65b9\u3060\u3068\u3001\u4f8b\u3067\u306e<span>result<\/span>\u306b\u306f\u5fc5\u305a\u5024\u304c\u8a2d\u5b9a\u3055\u308c\u308b\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u307e\u3059\u306e\u3067\u3001\u5909\u6570\u306e\u521d\u671f\u5316\u6f0f\u308c\u3084\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u307e\u307e\u3060\u3063\u305f\u2026\u3068\u3044\u3046\u3088\u3046\u306a\u3046\u3063\u304b\u308a\u30df\u30b9\u3092\u9632\u3052\u307e\u3059\u3002<\/p>\n<p>\u305d\u308c\u306b\u3001\u4f8b\u5916\u3092<span>throw<\/span>\u3059\u308b\u3053\u3068\u3067\u300c\u60f3\u5b9a\u3057\u3066\u3044\u308b\u5024\u4ee5\u5916\u306f\u7d76\u5bfe\u306b\u8a31\u53ef\u3057\u306a\u3044\u300d\u3068\u3044\u3046\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u306e\u610f\u601d\u3092\u8868\u73fe\u3067\u304d\u307e\u3059\u3002<span>1<\/span>\u3064\u76ee\u306e\u3084\u308a\u65b9\u3060\u3068\u3001\u8003\u616e\u6f0f\u308c\u306a\u306e\u304b\u3042\u308b\u3044\u306f\u5206\u304b\u3063\u3066\u3044\u3066\u305d\u3046\u3057\u3066\u3044\u308b\u306e\u304b\u3001\u8a2d\u8a08\u66f8\u3084\u30b3\u30e1\u30f3\u30c8\u3067\u3082\u6b8b\u3063\u3066\u3044\u306a\u3051\u308c\u3070\u308f\u304b\u3089\u306a\u3044\u3067\u3059\u3088\u306d\u3002<\/p>\n<h2><span id=\"Javaswitchif\">\uff13\uff0e\u3010Java\u3011switch\u6587\u3068<span>if<\/span>\u6587\u3068\u306e\u4f7f\u3044\u5206\u3051\u306e\u5224\u65ad\u57fa\u6e96<\/span><\/h2>\n<p>switch\u6587\u3068<span>if<\/span>\u6587\u3092\u4f7f\u3044\u5206\u3051\u308b\u6642\u306e\u5224\u65ad\u57fa\u6e96\u306e\u4e00\u3064\u306f\u3001\u5224\u5b9a\u51e6\u7406\u306b\u304b\u304b\u308b\u30b3\u30b9\u30c8\u3068\u901f\u3055\u3067\u3059\u3002<\/p>\n<p>if\u6587\u306f\u5168\u3066\u306e\u6761\u4ef6\u5224\u5b9a\u3092\u4e0a\u304b\u3089\u9806\u756a\u306b\u884c\u3046\u306e\u3067\u3001\u67d4\u8edf\u306a\u6761\u4ef6\u5224\u5b9a\u304c\u3067\u304d\u308b\u4ee3\u308f\u308a\u306b\u3001\u5224\u5b9a\u306b\u304b\u304b\u308b\u30b3\u30b9\u30c8<span>(<\/span>\u51e6\u7406\u6642\u9593\u542b\u3080<span>)<\/span>\u304c\u5927\u304d\u304f\u306a\u308a\u304c\u3061\u3067\u3059\u3002\u5224\u5b9a\u6761\u4ef6\u304c\u8907\u96d1\u306b\u306a\u308c\u3070\u306a\u308b\u307b\u3069\u3001<span>if<\/span>\u6587\u5168\u4f53\u306e\u5b9f\u884c\u30b3\u30b9\u30c8\u304c\u4e0a\u304c\u3063\u3066\u3044\u304d\u307e\u3059\u3002\u826f\u304f\u767a\u751f\u3059\u308b\u6761\u4ef6\u307b\u3069<span>if<\/span>\u6587\u306e\u524d\u306e\u65b9\u306b\u6301\u3063\u3066\u304f\u308b\u3079\u304d\u306a\u306e\u306f\u3001\u3053\u308c\u304c\u7406\u7531\u3067\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">if (\u5224\u5b9a\u6761\u4ef61) {\r\n\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n} else if (\u5224\u5b9a\u6761\u4ef62) {\r\n\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n} else if (\u5224\u5b9a\u6761\u4ef63) {\r\n\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n} else if (\u5224\u5b9a\u6761\u4ef64) {\r\n\t\/\/ \u4f55\u304b\u306e\u51e6\u7406\r\n} else {\r\n\t\/\/ \u3053\u3053\u306b\u6765\u308b\u305f\u3081\u306b\u306f\u3001\u3053\u3053\u307e\u3067\u306e\u5168\u3066\u306eif\u6587\u306e\u4e2d\u306e\u5224\u5b9a\u6761\u4ef6\u3092\u691c\u8a3c\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\r\n}<\/pre>\n<p>switch\u6587\u306f\u3001\u8a72\u5f53\u3059\u308b\u5024\u306e\u7b87\u6240\u3078\u51e6\u7406\u304c\u76f4\u63a5\u30b8\u30e3\u30f3\u30d7\u3059\u308b\u3001\u3044\u308f\u3086\u308b\u300c<span>GOTO<\/span>\u6587\u300d\u306e\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002<span>GOTO<\/span>\u6587\u306e\u3088\u3046\u306a\u51e6\u7406\u306f\u9078\u629e\u80a2\u304c\u3044\u304f\u3089\u591a\u304f\u3066\u3082\u30b8\u30e3\u30f3\u30d7\u306b\u5fc5\u8981\u306a\u6642\u9593\u306f\u307b\u307c\u4e00\u5b9a\u3067\u3001\u305d\u308c\u304c<span>switch<\/span>\u6587\u306e\u7279\u5fb4\u3067\u3082\u3042\u308a\u307e\u3059<span>(<\/span>\u3061\u306a\u307f\u306b\u3001<span>GOTO<\/span>\u6587\u306f\u6700\u8fd1\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u306b\u306f\u4ed5\u69d8\u4e0a\u3067\u5b58\u5728\u3057\u306a\u3044\u3053\u3068\u304c\u591a\u3044\u3067\u3059<span>)<\/span>\u3002<\/p>\n<p>\u3067\u3059\u306e\u3067\u3001\u4e0a\u306e<span>if<\/span>\u6587\u3067\u4f8b\u3048\u308b\u306a\u3089\u3001<span>switch<\/span>\u6587\u306f\u9014\u4e2d\u306e\u5224\u5b9a\u51e6\u7406<span>1<\/span>\uff5e<span>3<\/span>\u3092\u5b9f\u884c\u3059\u3089\u305b\u305a\u3001\u3044\u304d\u306a\u308a\u5224\u5b9a\u6761\u4ef6<span>4<\/span>\u306e\u30d6\u30ed\u30c3\u30af\u5185\u306b\u51e6\u7406\u304c\u79fb\u308b\u3001\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002\u3053\u308c\u304c<span>switch<\/span>\u6587\u3068<span>GOTO<\/span>\u6587\u304c\u540c\u3058\u3068\u8a00\u3048\u308b\u3068\u3053\u308d\u3067\u3059\u3002\u305f\u3060\u3057\u3001\u305d\u306e\u4ee3\u511f\u3068\u3057\u3066<span>switch<\/span>\u6587\u3067\u306f\u8907\u96d1\u306a\u6761\u4ef6\u5224\u5b9a\u306f\u884c\u3048\u307e\u305b\u3093\u3002<\/p>\n<p>\u5f93\u3063\u3066\u3001<span>switch<\/span>\u6587\u3068<span>if<\/span>\u6587\u306e\u4f7f\u3044\u5206\u3051\u306e\u65b9\u91dd\u306e\u4e00\u3064\u3068\u3057\u3066\u306f\u3001\u4ee5\u4e0b\u3092\u8003\u3048\u3066\u3001\u5f53\u3066\u306f\u307e\u308b\u3082\u306e\u304c\u591a\u3051\u308c\u3070<span>switch<\/span>\u6587\u2026\u3068\u3057\u3066\u3082\u826f\u3044\u306e\u3067\u306f\u306a\u3044\u306e\u3067\u3057\u3087\u3046\u304b\u3002\u3082\u3061\u308d\u3093\u3001\u898b\u305f\u76ee\u304c\u597d\u304d\u3068\u3044\u3046\u306e\u3082\u3042\u308a\u306a\u306e\u3067\u3059\u304c\u3001\u9078\u3093\u3060\u7406\u7531\u3092\u304d\u3061\u3093\u3068\u8a00\u3048\u308b\u3068\u683c\u597d\u3044\u3044\u3067\u3059\u3088\u306d\u3002<\/p>\n<ul>\n<li>\u5224\u5b9a\u6761\u4ef6\u3067\u4f7f\u3046\u5909\u6570\u306f<span>1<\/span>\u3064\u3060\u3051\u304b<\/li>\n<li>\u5224\u5b9a\u6761\u4ef6\u3067\u4f7f\u3046\u5909\u6570\u306e\u578b\u306f<span>1<\/span>\u3064\u3060\u3051\u3001\u304b\u3064<span>switch<\/span>\u6587\u3067\u4f7f\u3048\u308b\u3082\u306e\u304b<\/li>\n<li>\u5224\u5b9a\u6761\u4ef6\u306f<span> == <\/span>\u3042\u308b\u3044\u306f<span> equals <\/span>\u3060\u3051\u304b<\/li>\n<li>\u5224\u5b9a\u6761\u4ef6\u306e\u5024\u3001\u7dcf\u6570\u304c\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u6642\u306b\u9759\u7684\u306b\u6c7a\u5b9a\u3067\u304d\u308b\u304b<\/li>\n<li>\u5224\u5b9a\u51e6\u7406\u306e\u901f\u5ea6\u304c\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u8981\u4ef6\u30fb\u4ed5\u69d8\u4e0a\u3067\u91cd\u8981\u304b<\/li>\n<\/ul>\n<h2><span id=\"JavaswitchJEP_325Switch_Expressions\">\uff14\uff0e\u3010Java\u3011switch\u306e\u672a\u6765\u3001<span>JEP 325:Switch Expressions<\/span><\/span><\/h2>\n<p>switch\u306e\u69cb\u6587\u305d\u306e\u3082\u306e\u306f<span>Java<\/span>\u306e\u521d\u671f\u304b\u3089\u5909\u308f\u3063\u3066\u3044\u307e\u305b\u3093\u3002\u3053\u308c\u307e\u3067\u306e<span>Java<\/span>\u4ed5\u69d8\u306e\u6539\u5b9a\u3067\u306f\u3001\u6271\u3048\u308b\u5024\u306e\u578b\u304c\u5897\u3048\u305f\u3060\u3051\u3067\u3057\u305f\u3002\u3082\u3061\u308d\u3093\u3001<span>switch<\/span>\u6587\u3067<span>enum<\/span>\u3084<span>String<\/span>\u304c\u6271\u3048\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u3060\u3051\u3067\u3082\u5927\u304d\u306a\u9032\u6b69\u3067\u3059\u3002<\/p>\n<p>\u3067\u3059\u304c\u3001\u300c<span>JEP 325 Switch Expressions<\/span>\u300d\u306b\u3088\u308a<span>switch<\/span>\u6587\u306e\u69cb\u6587\u306b\u5927\u304d\u306a\u5909\u5316\u304c\u8a2a\u308c\u308b\u4e88\u5b9a\u306a\u306e\u3067\u3001\u5148\u53d6\u308a\u3057\u3066\u77e5\u8b58\u3092\u5f97\u3066\u304a\u3044\u3066\u3082\u826f\u3044\u3067\u3057\u3087\u3046\u3002<span>JEP 325<\/span>\u306f<span>Java 12<\/span>\u3067\u53d6\u308a\u8fbc\u307e\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u4ed5\u69d8\u3067\u3059<span>(2018\/10<\/span>\u6642\u70b9<span>)<\/span>\u3002<\/p>\n<p>JEP 325\u3067\u306f\u3001<span>switch<\/span>\u6587\u81ea\u4f53\u304c\u623b\u308a\u5024\u3092\u8fd4\u305b\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u308a\u3001\u30e9\u30e0\u30c0\u5f0f\u306e\u3088\u3046\u306b\u4f7f\u3048\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070\u4ee5\u4e0b\u306e\u3082\u306e\u306f<span>JEP 325<\/span>\u304b\u3089\u629c\u7c8b\u3057\u305f\u3082\u306e\u3067\u3059\u304c\u3001\u3082\u3063\u3068<span>switch<\/span>\u6587\u3092\u6d3b\u7528\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u305d\u3046\u3067\u3059\u306d\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ case\u3067\u5b9f\u884c\u3059\u308b\u6587\u3092\u30e9\u30e0\u30c0\u5f0f\u306e\u3088\u3046\u306b\u66f8\u3051\u3001case\u3054\u3068\u306b\u30d6\u30ed\u30c3\u30af\u304c\u72ec\u7acb\u3059\u308b!!\r\nswitch (day) {\r\n    case MONDAY, FRIDAY, SUNDAY -&gt; System.out.println(6);\r\n    case TUESDAY                -&gt; System.out.println(7);\r\n    case THURSDAY, SATURDAY     -&gt; System.out.println(8);\r\n    case WEDNESDAY              -&gt; System.out.println(9);\r\n}<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ swtich\u6587\u81ea\u4f53\u304c\u623b\u308a\u5024\u3092\u6301\u3064!!\r\nint numLetters = switch (day) {\r\n    case MONDAY, FRIDAY, SUNDAY -&gt; 6;\r\n    case TUESDAY                -&gt; 7;\r\n    case THURSDAY, SATURDAY     -&gt; 8;\r\n    case WEDNESDAY              -&gt; 9;\r\n};<\/pre>\n<pre class=\"prettyprint lang:default decode:true\">\/\/ switch\u306e\u5f0f\u3068\u623b\u308a\u5024\u306e\u578b\u304c\u9055\u3063\u3066\u3044\u3066\u3082\u3044\u3044!!\r\nint result = switch (s) {\r\n    case \"Foo\": \r\n        break 1;\r\n    case \"Bar\":\r\n        break 2;\r\n    default:\r\n        System.out.println(\"Neither Foo nor Bar, hmmm...\");\r\n        break 0;\r\n};<\/pre>\n<h2><span id=\"i-3\">\uff15\uff0e\u307e\u3068\u3081<\/span><\/h2>\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f<span>switch<\/span>\u306e\u57fa\u672c\u3068\u306f\u307e\u308a\u30dd\u30a4\u30f3\u30c8\u3001\u306a\u305c<span>switch<\/span>\u304c\u65e9\u3044\u306e\u304b\u3092\u304a\u4f1d\u3048\u3057\u307e\u3057\u305f\u3002<span>switch<\/span>\u6587\u306b\u306f<span>if<\/span>\u6587\u306b\u306f\u306a\u3044\u7279\u5fb4\u304c\u3042\u308a\u307e\u3059\u306e\u3067\u3001\u305c\u3072\u6d3b\u7528\u3057\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u307e\u305f\u3001\u73fe\u5728\u6642\u70b9\u3067\u958b\u767a\u4e2d\u306e<span>JEP 325<\/span>\u3067\u306f\u3001<span>switch<\/span>\u6587\u306e\u69cb\u6587\u304c\u62e1\u5f35\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u3088\u3046\u306a\u60c5\u5831\u3092\u5148\u53d6\u308a\u3059\u308b\u3053\u3068\u3067\u3001\u5468\u56f2\u306e\u4e00\u6b69\u5148\u3092\u884c\u3051\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u306d\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Java\u306eswitch\u6587\u306f\u3001\u6761\u4ef6\u5206\u5c90\u306e\u69cb\u6587\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001\u307e\u305a\u306fswitch\u6587\u306e\u69cb\u6587\u3068\u4f7f\u3044\u65b9\u306e\u57fa\u672c\u3092\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002 \u306a\u304a\u3001\u5b9f\u969b\u306bswitch\u3092\u4f7f\u3046\u969b\u306f\u3001\u540c\u3058\u6761\u4ef6\u5206\u5c90\u306e\u69cb\u6587\u3067\u3042\u308bif\u6587\u3068\u306e\u4f7f\u3044\u5206\u3051\u306b\u8ff7\u3046\u304b\u3082\u3057\u308c\u307e [&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\/833"}],"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=833"}],"version-history":[{"count":7,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/833\/revisions"}],"predecessor-version":[{"id":5683,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/833\/revisions\/5683"}],"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=833"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/categories?post=833"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}