{"id":34393,"date":"2019-03-14T12:23:00","date_gmt":"2019-03-14T04:23:00","guid":{"rendered":"https:\/\/blog.jetbrains.com\/cn\/?p=234"},"modified":"2020-02-10T23:46:16","modified_gmt":"2020-02-10T15:46:16","slug":"java-12-intellij-idea","status":"publish","type":"post","link":"https:\/\/blog.jetbrains.com\/zh-hans\/2019\/03\/14\/java-12-intellij-idea\/","title":{"rendered":"Java 12 \u548c IntelliJ IDEA"},"content":{"rendered":"\u901a\u8fc7 switch \u8868\u8fbe\u5f0f\uff0cJava 12 \u6b63\u5728\u589e\u5f3a\u5176\u57fa\u672c\u8bed\u8a00\u7ed3\u6784\u4e4b\u4e00 \u2013\u00a0switch\u00a0\u2013 \u6539\u5584\u5f00\u53d1\u4eba\u5458\u7684\u65e5\u5e38\u7f16\u7a0b\u4f53\u9a8c\u3002\r\n\u4f18\u70b9\u662f\u591a\u65b9\u9762\u7684\u3002\u4e0e'\u4f20\u7edf' switch \u7ed3\u6784\u76f8\u6bd4\uff0cswitch \u8868\u8fbe\u5f0f\u53ef\u4ee5\u8fd4\u56de\u503c\u3002\u4f7f\u7528 switch \u5206\u652f\u5b9a\u4e49\u591a\u4e2a\u5e38\u91cf\u7684\u80fd\u529b\u4ee5\u53ca\u6539\u8fdb\u7684\u4ee3\u7801\u8bed\u4e49\u4f7f\u5176\u7b80\u6d01\u3002\u901a\u8fc7\u5220\u9664 switch \u5206\u652f\u7684\u9ed8\u8ba4\u901a\u8fc7\u6761\u4ef6\uff0c\u964d\u4f4e\u4e86\u5728 switch \u8868\u8fbe\u5f0f\u4e2d\u5f15\u5165\u903b\u8f91\u9519\u8bef\u7684\u53ef\u80fd\u6027\u3002\r\n\u5728\u8fd9\u7bc7\u535a\u5ba2\u4e2d\uff0c\u6211\u4eec\u5c06\u4ecb\u7ecd\u4f7f\u7528\u73b0\u6709 switch \u8bed\u53e5\u7684\u96be\u70b9\uff0c\u5b9a\u4e49\u00a0switch \u8868\u8fbe\u5f0f\uff0c\u5e76\u4e14\u89e3\u91ca\u5b83\u4eec\u4e3a\u4ec0\u4e48\u5bf9\u60a8\u6709\u597d\u5904\u3002\r\n\u6211\u4eec\u5f00\u59cb\u5427\u3002\r\n\u4f20\u7edf switch \u67b6\u6784\r\n\u5982\u679c\u5c06 switch \u67b6\u6784\u89c6\u4e3a\u591a\u8def\u6761\u4ef6\uff0c\u90a3\u4e48\u4f7f\u7528\u8868\u8fbe\u5f0f\u4f3c\u4e4e\u66f4\u5408\u9002\u3002\u4f46\u5728\u90a3\u4e4b\u524d\uff0cswitch \u53ea\u80fd\u7528\u4f5c\u8bed\u53e5\u3002\u5f53\u524d\u7684 switch \u8bed\u6cd5\u53d7\u9650\u4e14\u5197\u957f\u3002\u7ecf\u5e38\u5bfc\u81f4\u5bb9\u6613\u51fa\u9519\u3001\u96be\u4ee5\u8c03\u8bd5\u7684\u4ee3\u7801\u3002\r\n\u8fd9\u662f\u4e00\u4e2a\u4f7f\u7528 switch \u8bed\u53e5\uff0c\u6839\u636e\u7ed9\u5b83\u7684\u00a0size\u00a0\u6765\u8ba1\u7b97\u6905\u5b50\u00a0height\u00a0\u7684\u793a\u4f8b\uff1a\r\n\r\npublic enum Size {S, M, L, XL};\r\npublic class Chair {\r\n    public void calcHeight(Size size) {\r\n        int height = 0; \r\n        switch (size) {\r\n            case S:\r\n                height = 18;\r\n            case M:\r\n                height = 20;\r\n                break;\r\n            case L:\r\n                height = 25;\r\n                break;\r\n        }\r\n    }\r\n}\r\n\u4e0a\u8ff0\u4ee3\u7801\u6709\u51e0\u4e2a\u95ee\u9898\uff1a\r\n\r\n\t\r\n\u91cd\u590d\u7684\u00a0break\u00a0\u548c\u8d4b\u503c\u8bed\u53e5\u4e3a\u4ee3\u7801\u6dfb\u52a0\u566a\u58f0\u3002\r\n\r\n\t\r\n\u4ee3\u7801\u5197\u957f\u4f7f\u5176\u96be\u4ee5\u7406\u89e3\u3002\r\n\r\n\t\r\nSwitch \u5206\u652f\u7684\u9ed8\u8ba4\u901a\u8fc7\u6761\u4ef6\u6f5c\u85cf\u903b\u8f91\u9519\u8bef \u2013 case \u6807\u7b7e\u00a0S\u00a0\u7f3a\u5c11\u7684\u00a0break\u00a0\u8bed\u53e5\u8ba9\u63a7\u5236\u843d\u5165 case \u6807\u7b7e\u00a0M\u3002\u8fd9\u5bfc\u81f4\u5f53\u60a8\u6267\u884c\u00a0calcHeight(Size.S)\u65f6\uff0cheight\u00a0\u503c\u4e3a 20 \u800c\u4e0d\u662f 18\u3002\r\n\r\n\r\nSwitch \u8868\u8fbe\u5f0f\r\n\u8ba9\u6211\u4eec\u4f7f\u7528 switch \u8868\u8fbe\u5f0f\u91cd\u5199\u524d\u9762\u7684\u793a\u4f8b\u3002\u5728 IntelliJ IDEA \u4e2d\uff0c\u60a8\u53ef\u4ee5\u5bf9\u00a0switch\u00a0\u5173\u952e\u5b57\u4f7f\u7528 Alt+Enter \u6765\u67e5\u770b\u5efa\u8bae\u3002\r\n\u00a0\u9009\u62e9\u2018\u4ee5\u589e\u5f3a\u7684 switch \u8bed\u53e5\u66ff\u6362 (Replace with enhanced \u2018switch\u2019 statement)\u2019\uff0c\u5c06\u4f20\u7edf\u00a0switch\u00a0\u8bed\u53e5\u8f6c\u6362\u4e3a switch \u8868\u8fbe\u5f0f\uff1a\r\n\r\n\r\n\r\n\u4e0a\u8ff0\u4ee3\u7801\u6709\u51e0\u4e2a\u4f18\u70b9\uff1a\r\n\r\n\t\r\nSwitch \u5206\u652f\u4e2d\u7684\u4ee3\u7801\u7b80\u6d01\u6613\u8bfb\u3002\u60a8\u5728\u00a0->\u00a0\u53f3\u8fb9\u5b9a\u4e49\u8981\u6267\u884c\u7684\u5185\u5bb9\u3002\r\n\r\n\t\r\nSwitch \u5206\u652f\u53ef\u4ee5\u8fd4\u56de\u4e00\u4e2a\u503c\uff0c\u8be5\u503c\u53ef\u7528\u4e8e\u4e3a\u53d8\u91cf\u8d4b\u503c\u3002\r\n\r\n\t\r\nSwitch \u5206\u652f\u4e0d\u9700\u8981\u00a0break\u00a0\u8bed\u53e5\u6765\u6807\u8bb0\u5176\u7ed3\u675f\u3002\u7f3a\u5c11\u00a0break\u00a0\u8bed\u53e5\uff0c\u63a7\u5236\u4e0d\u4f1a\u8fdb\u5165 switch \u6807\u7b7e \u2013 \u4ece\u800c\u907f\u514d\u903b\u8f91\u9519\u8bef\u3002\r\n\r\n\r\n\u8fd4\u56de\u503c vs.\u6267\u884c\u8bed\u53e5\r\n\u5f53\u60a8\u4e0d\u4f7f\u7528 switch \u8868\u8fbe\u5f0f\u8fd4\u56de\u503c\u65f6\uff0cswitch \u5206\u652f\u53ef\u4ee5\u9009\u62e9\u6267\u884c\u8bed\u53e5\u6216\u8bed\u53e5\u5757\uff0c\u751a\u81f3\u629b\u51fa\u5f02\u5e38\uff1a\r\n\r\n\r\n\r\npublic enum Size {S, M, L, XL};\r\npublic class NotReturningValueFromSwitchLabel {\r\n    public void calcHeight(Size size) {\r\n        int height = 0; \r\n        switch (size) {\r\n            case S -> height = 18;\r\n            case M -> { \r\n                           height = 20; \r\n                           System.out.println(height);\r\n                      }\r\n            case L -> height = 25;\r\n        }\r\n    }\r\n}\r\n\r\n\r\n\u5904\u7406\u6240\u6709\u53ef\u80fd\u53c2\u6570\u503c\r\n\u5f53\u60a8\u4f7f\u7528 switch \u8868\u8fbe\u5f0f\u8fd4\u56de\u4e00\u4e2a\u503c\u65f6\uff0c\u5b83\u5e94\u8be5\u53ef\u4ee5\u5904\u7406\u6240\u6709\u53ef\u80fd\u7684\u503c\uff0c\u60a8\u53ef\u4ee5\u5c06\u8fd9\u4e9b\u503c\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u7ed9\u5b83\u3002\u4f8b\u5982\uff0c\u5982\u679c\u60a8\u5fd8\u4e86\u4e0e\u67d0\u4e2a\u679a\u4e3e\u5e38\u91cf\u5bf9\u5e94\u7684 case \u6807\u7b7e\uff0cIntelliJ IDEA \u53ef\u4ee5\u68c0\u6d4b\u5230\u3002\u5b83\u53ef\u4ee5\u63d2\u5165\u7279\u5b9a case \u6807\u7b7e\u6216\u9ed8\u8ba4\u00a0case \u6807\u7b7e\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cIntelliJ IDEA \u6839\u636e\u53d8\u91cf\u7c7b\u578b\u63d2\u5165\u9ed8\u8ba4\u503c\u3002\r\n\u00a0\u60a8\u53ef\u4ee5\u7f16\u8f91\u5360\u4f4d\u7b26\u503c\uff1a\r\n\r\n\r\n\r\n\u679a\u4e3e\u4ee5\u5916\u7684\u7c7b\u578b\u53ef\u4ee5\u6709\u65e0\u9650\u503c\u3002\r\n\r\n\u5f53\u60a8\u4f20\u9012\u00a0byte\u3001short\u3001int\u00a0\u6216\u00a0String\u00a0\u7b49\u7c7b\u578b\uff0c\u5e76\u4e14\u5fd8\u8bb0\u5305\u542bdefault\u00a0\u6807\u7b7e\uff0cIntelliJ IDEA \u53ef\u4ee5\u68c0\u6d4b\u5230\u5e76\u4fee\u590d\u8fd9\u4e2a\u95ee\u9898\uff1a\r\n\r\n\r\n\u5728\u540c\u4e00\u4e2a case \u6807\u7b7e\u4e2d\u5b9a\u4e49\u591a\u4e2a\u5e38\u91cf\r\n\u4e0d\u540c\u4e8e switch \u8bed\u53e5\uff0cswitch \u8868\u8fbe\u5f0f\u5141\u8bb8\u60a8\u5728 case \u6807\u7b7e\u4e2d\u5b9a\u4e49\u7528\u9017\u53f7\u5206\u9694\u7684\u591a\u4e2a\u5e38\u91cf\u3002\r\n\u8fd9\u6837\u51cf\u5c11\u4e86\u4ee3\u7801\u5197\u4f59 - \u60a8\u53ef\u4ee5\u4e3a\u6240\u6709 case \u6807\u7b7e\u6267\u884c\u76f8\u540c\u7684\u4ee3\u7801\u3002\u5982\u679c\u5728 switch \u8868\u8fbe\u5f0f\u4e2d\u4e3a case \u6807\u7b7e\u5b9a\u4e49\u4e86\u5197\u4f59\u4ee3\u7801\uff0cIntelliJ IDEA \u53ef\u4ee5\u4fee\u590d\u8fd9\u4e2a\u95ee\u9898\uff1a\r\n\r\n\r\nSwitch \u5206\u652f\u4e2d\u7684\u5c40\u90e8\u53d8\u91cf\u548c break \u8bed\u53e5\r\n\u53ef\u4ee5\u901a\u8fc7 switch \u8868\u8fbe\u5f0f\u5728 switch \u5206\u652f\u4e2d\u5b9a\u4e49\u5c40\u90e8\u53d8\u91cf\u3002\u4ee3\u7801\u5757\u5fc5\u987b\u5305\u542b\u6307\u5b9a\u8981\u8fd4\u56de\u7684\u503c\u7684break\u00a0\u8bed\u53e5\uff1a\r\n\r\nenum Size {S, M, L, XL};\r\n\r\npublic class LocalVariablesWithSwitch {\r\n    public void assignValue(Size size) {\r\n        int height = 0;\r\n        height = switch(size) {\r\n            case S -> 18;\r\n            case M -> {\r\n                    int weight = 19;\r\n                    break (weight > 10 ? 15 : 20); \r\n                } \r\n            case L, XL -> 25;\r\n        };\r\n    }\r\n}\r\n\r\n\u503c M \u7684 case \u6807\u7b7e\u5b9a\u4e49\u4e86\u4e00\u4e2a\u5757\u8bed\u53e5\u3002\u4ee3\u7801\u5757\u4e5f\u53ef\u5b9a\u4e49\u5c40\u90e8\u53d8\u91cf\uff08\u672c\u793a\u4f8b\u4e2d\u7684 weight\uff09\u3002\u5c40\u90e8\u53d8\u91cf\u00a0weight\u00a0\u7684\u8303\u56f4\u548c\u53ef\u8bbf\u95ee\u6027\u4ec5\u9650\u4e8e case \u6807\u7b7e M\u3002\u8bf7\u6ce8\u610f switch \u8868\u8fbe\u5f0f\u5982\u4f55\u4f7f\u7528\u00a0break\u00a0\u8bed\u53e5\u6765\u8fd4\u56de\u503c\u3002\r\n\u4ee5\u9632\u60a8\u5fd8\u8bb0\u4e3a switch \u5206\u652f\u5b9a\u4e49\u8fd4\u56de\u503c, \u56e0\u6b64 IntelliJ IDEA \u4ee5\u4e0b\u5212\u7ebf\u5f3a\u8c03\u00a0case\u3002\u5f53\u60a8\u628a\u9f20\u6807\u7f6e\u4e8e\u5176\u4e0a\uff0c\u53ef\u4ee5\u67e5\u770b\u5173\u4e8e\u7f3a\u5c11\u8fd4\u56de\u503c\u7684\u6d88\u606f\uff1a\r\n\r\n\r\n\u9884\u6f14\u8bed\u8a00\uff08Preview language\uff09\u529f\u80fd\r\nSwitch \u8868\u8fbe\u5f0f\u662f\u4e00\u79cd\u9884\u6f14\u8bed\u8a00\u529f\u80fd\u3002\u8fd9\u57fa\u672c\u4e0a\u610f\u5473\u7740\u5373\u4f7f\u5b83\u662f\u5b8c\u6574\u7684\uff0c\u4e5f\u6709\u53ef\u80fd\u5728\u4eca\u540e\u7684 Java \u7248\u672c\u4e2d\u4e0d\u88ab\u786e\u8ba4\u4e3a\u6c38\u4e45\u529f\u80fd\u3002\u8fd9\u662f\u6709\u539f\u56e0\u7684\u3002\r\nJava \u8fd0\u884c\u5728\u6570\u5341\u4ebf\u53f0\u8bbe\u5907\u4e0a\uff0c\u800c\u4e14\u6709\u6570\u767e\u4e07\u5f00\u53d1\u4eba\u5458\u4f7f\u7528\u8fd9\u79cd\u8bed\u8a00\u3002Java \u8bed\u8a00\u65b0\u529f\u80fd\u7684\u4efb\u4f55\u9519\u8bef\u90fd\u4f1a\u5e26\u6765\u9ad8\u98ce\u9669\u3002\u5c06\u67d0\u9879\u8bed\u8a00\u529f\u80fd\u6c38\u4e45\u52a0\u5165 Java \u524d\uff0cJava \u67b6\u6784\u5e08\u4f1a\u8bc4\u4f30\u5f00\u53d1\u4eba\u5458\u5bf9\u5b83\u7684\u770b\u6cd5 \u2013 \u5176\u597d\u574f\u7a0b\u5ea6\u5982\u4f55\u3002\u6839\u636e\u53cd\u9988\uff0c\u5728\u6dfb\u52a0\u5230 Java SE \u524d\uff0c\u53ef\u80fd\u4f1a\u4f18\u5316\u6216\u5b8c\u5168\u5220\u9664\u9884\u6f14\u529f\u80fd\u3002\r\n\u6240\u4ee5\uff0c\u5982\u679c\u60a8\u6709\u4efb\u4f55\u5173\u4e8e Switch \u8868\u8fbe\u5f0f\u7684\u53cd\u9988\uff0c\u8bf7\u5728\u6b64\u5206\u4eab\u3002\r\n\r\nIntelliJ IDEA \u914d\u7f6e\r\n\u7531\u4e8e Switch \u8868\u8fbe\u5f0f\u662f\u4e00\u9879 Java 12 \u8bed\u8a00\u529f\u80fd\uff0c\u8bf7\u4e0b\u8f7d\u5e76\u5b89\u88c5\u00a0OpenJDK 12\uff0c\u5e76\u4e14\u914d\u7f6e\u4e3a\u4e0e IntelliJ IDEA \u4e00\u8d77\u4f7f\u7528\uff1a\r\n\r\nJava \u6b63\u5728\u4e0d\u65ad\u53d1\u5c55\uff0c\u800c switch \u8868\u8fbe\u5f0f\u6b63\u662f Java 12 \u4e2d\u4e00\u9879\u53d7\u6b22\u8fce\u7684\u53d8\u5316\u3002\r\n\u5feb\u4e50\u7f16\u7a0b\uff01\r\n\r\n\u539f\u6587\u53d1\u8868\u4e8e2019\u5e742\u670822\u65e5\uff0c\u4f5c\u8005\u00a0Mala Gupta","protected":false},"excerpt":{"rendered":"\u901a\u8fc7 switch \u8868\u8fbe\u5f0f\uff0cJava 12 \u6b63\u5728\u589e\u5f3a\u5176\u57fa\u672c\u8bed\u8a00\u7ed3\u6784\u4e4b\u4e00 \u2013\u00a0switch\u00a0\u2013 \u6539\u5584\u5f00\u53d1\u4eba\u5458\u7684\u65e5\u5e38\u7f16\u7a0b\u4f53\u9a8c\u3002\u4f18\u70b9\u662f\u591a\u65b9\u9762\u7684\u3002\u4e0e'\u4f20\u7edf' switch \u7ed3\u6784\u76f8\u6bd4\uff0cswitch \u8868\u8fbe\u5f0f\u53ef\u4ee5\u8fd4\u56de\u503c\u3002\u4f7f\u7528 switch \u5206\u652f\u5b9a\u4e49\u591a\u4e2a\u5e38\u91cf\u7684\u80fd\u529b\u4ee5\u53ca\u6539\u8fdb\u7684\u4ee3\u7801\u8bed\u4e49\u4f7f\u5176\u7b80\u6d01\u3002\u901a\u8fc7\u5220\u9664 switch \u5206\u652f\u7684\u9ed8\u8ba4\u901a\u8fc7\u6761\u4ef6\uff0c\u964d\u4f4e\u4e86\u5728 switch \u8868\u8fbe\u5f0f\u4e2d\u5f15\u5165\u903b\u8f91\u9519\u8bef\u7684\u53ef\u80fd\u6027\u3002\u5728\u8fd9\u7bc7\u535a\u5ba2\u4e2d\uff0c\u6211\u4eec","protected":false},"author":{"name":"Lei","link":"https:\/\/blog.jetbrains.com\/zh-hans\/author\/lei-zhaojetbrains-com"},"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[4759,2347,4757],"tags":[5335,155],"cross-post-tag":[],"acf":[],"featured_image":null,"_links":{"self":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/posts\/34393"}],"collection":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/users\/814"},{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/users\/814"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/comments?post=34393"}],"version-history":[{"count":0,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/posts\/34393\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/media?parent=34393"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/categories?post=34393"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/tags?post=34393"},{"taxonomy":"cross-post-tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/zh-hans\/wp-json\/wp\/v2\/cross-post-tag?post=34393"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}