{"id":342526,"date":"2023-04-13T11:17:23","date_gmt":"2023-04-13T10:17:23","guid":{"rendered":"https:\/\/blog.jetbrains.com\/?post_type=idea&p=342526"},"modified":"2023-04-13T11:19:06","modified_gmt":"2023-04-13T10:19:06","slug":"java-20-and-intellij-idea","status":"publish","type":"idea","link":"https:\/\/blog.jetbrains.com\/zh-hans\/idea\/2023\/04\/java-20-and-intellij-idea\/","title":{"rendered":"Java 20 \u548c IntelliJ IDEA"},"content":{"rendered":"

\u672c\u4eba\u64b0\u5199\u6709\u5173\u65b0 Java \u7248\u672c\u7684\u6587\u7ae0\u5df2\u6709\u4e00\u6bb5\u65f6\u95f4\uff08\u81ea Java 10 \u4ee5\u6765\uff09\uff0c\u6211\u5f88\u559c\u6b22\u5f00\u53d1\u8005\u4eec\u6bcf\u516d\u4e2a\u6708\u5c31\u6709\u673a\u4f1a\u4e86\u89e3\u548c\u4f7f\u7528\u65b0\u7684 Java \u529f\u80fd\u8fd9\u79cd\u6a21\u5f0f\u3002<\/p>\n

\u76f8\u6bd4\u4e4b\u524d\u7684\u4e00\u4e9b\u7248\u672c\uff0cJava 20 \u7684\u65b0\u589e\u529f\u80fd\u76f8\u5bf9\u8f83\u5c11\u3002 \u5b83\u5f15\u5165\u4e86\u4f5c\u7528\u57df\u503c<\/a>\u4f5c\u4e3a\u5b75\u5316 API<\/a>\uff0c\u901a\u8fc7\u5728\u7ebf\u7a0b\u5185\u548c\u8de8\u7ebf\u7a0b\u5171\u4eab\u4e0d\u53ef\u53d8\u6570\u636e\u6765\u652f\u6301\u865a\u62df\u7ebf\u7a0b\u3002 \u5728\u5b83\u7684\u7b2c\u4e8c\u4e2a\u9884\u89c8\u7248\u4e2d\uff0c\u8bb0\u5f55\u6a21\u5f0f<\/a>\u6539\u8fdb\u4e86\u5bf9\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7684\u652f\u6301\uff0c\u5e76\u652f\u6301\u5728\u589e\u5f3a for \u8bed\u53e5\u4e2d\u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f\u3002 \u5728\u5b83\u7684\u7b2c\u56db\u4e2a\u9884\u89c8\u7248\u4e2d\uff0cswitch \u7684\u6a21\u5f0f\u5339\u914d<\/a>\u6539\u8fdb\u4e86\u5b83\u5728\u5904\u7406\u8be6\u5c3d switch\u3001\u7b80\u5316 switch \u6807\u7b7e\u548c\u63a8\u65ad\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7684\u7c7b\u578b\u5b9e\u53c2\u65f6\u7684\u4f7f\u7528\u3002<\/p>\n

\u5728 Java 20 \u7684\u7b2c\u4e8c\u4e2a\u9884\u89c8\u7248\u4e2d\uff0cForeign Function & Memory API<\/a> \u7ee7\u7eed\u6539\u8fdb\u5176\u529f\u80fd\uff0c\u4f7f Java \u4ee3\u7801\u80fd\u591f\u4e0e JVM \u5916\u90e8\u7684\u4ee3\u7801\u548c\u6570\u636e\u8fdb\u884c\u5bf9\u8bdd\u3002 \u865a\u62df\u7ebf\u7a0b<\/a>\u662f\u4e00\u79cd\u8f7b\u91cf\u7ea7\u7ebf\u7a0b\uff0c\u5b83\u5c06\u5f7b\u5e95\u6539\u53d8\u60a8\u521b\u5efa\u591a\u7ebf\u7a0b\u5e94\u7528\u7a0b\u5e8f\u7684\u65b9\u5f0f\u3002\u865a\u62df\u7ebf\u7a0b\u53d7\u7ed3\u6784\u5316\u5e76\u53d1<\/a>\u652f\u6301\uff0c\u5728\u6700\u65b0 Java \u7248\u672c\u7684\u53e6\u4e00\u4e2a\u9884\u89c8\u7248\u4e2d\u63a8\u51fa\u3002 Vector API<\/a> \u76ee\u524d\u5904\u4e8e\u7b2c\u4e94\u4e2a\u9884\u89c8\u7248\u9636\u6bb5\uff0c\u53ef\u4ee5\u5e2e\u52a9\u60a8\u5728\u4ee3\u7801\u4e2d\u8fdb\u884c\u77e2\u91cf\u8ba1\u7b97\u3002<\/p>\n

\u5728\u8fd9\u7bc7\u535a\u6587\u4e2d\uff0c\u6211\u5c06\u4ecb\u7ecd IntelliJ IDEA \u5728\u8bed\u8a00\u529f\u80fd\u65b9\u9762\u7684\u652f\u6301\uff0c\u4f8b\u5982\u8bb0\u5f55\u6a21\u5f0f\u548c switch \u7684\u6a21\u5f0f\u5339\u914d\uff0c\u5e76\u5c06\u7279\u522b\u4ecb\u7ecd\u6700\u6709\u8da3\u7684\u53d8\u5316\uff0c\u4f8b\u5982\u6539\u8fdb\u4e86\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7684\u7c7b\u578b\u63a8\u65ad\u3001\u8be6\u5c3d switch \u8bed\u53e5\u548c\u8868\u8fbe\u5f0f\uff0c\u4ee5\u53ca\u589e\u5f3a for<\/code> \u8bed\u53e5\u5934\u4e2d\u7684\u8bb0\u5f55\u6a21\u5f0f\u65b9\u9762\u7684\u652f\u6301\u3002<\/p>\n

\u6211\u4eec\u5f00\u59cb\u5427\u3002<\/p>\n

\"\"<\/figure>\n

IntelliJ IDEA \u914d\u7f6e<\/h2>\n

IntelliJ IDEA 2023.1 \u4e2d\u63d0\u4f9b\u4e86\u5bf9 Java 20 \u7684\u652f\u6301\u3002 \u672a\u6765\u7684 IntelliJ IDEA \u7248\u672c\u5c06\u63d0\u4f9b\u66f4\u591a\u652f\u6301\u3002<\/p>\n

\u8981\u4f7f\u7528 Java 20 \u4e2d\u8bf8\u5982\u8bb0\u5f55\u6a21\u5f0f\u548c switch \u7684\u6a21\u5f0f\u5339\u914d\u7b49\u65b0\u8bed\u8a00\u529f\u80fd\uff0c\u8bf7\u8f6c\u5230 ProjectSettings | Project<\/i>\uff08\u9879\u76ee\u8bbe\u7f6e | \u9879\u76ee\uff09\uff0c\u5c06 Project SDK\uff08\u9879\u76ee SDK\uff09\u8bbe\u7f6e\u4e3a 20\uff0c\u5c06 Project language level\uff08\u9879\u76ee\u8bed\u8a00\u7ea7\u522b\uff09\u8bbe\u7f6e\u4e3a 20 (Preview) \u2013 Record patterns (second preview), Pattern Matching for switch (fourth preview)<\/i>\uff1a<\/p>\n

\"\"<\/figure>\n

\u00a0<\/p>\n

\u60a8\u53ef\u4ee5\u4f7f\u7528\u7cfb\u7edf\u4e0a\u5df2\u7ecf\u4e0b\u8f7d\u7684\u4efb\u610f\u7248\u672c JDK\uff0c\u4e5f\u53ef\u4ee5\u70b9\u51fb Edit<\/i>\uff08\u7f16\u8f91\uff09\uff0c\u7136\u540e\u9009\u62e9 Add SDK > <\/i>Download JDK\u2026<\/i>\uff08\u6dfb\u52a0 SDK > \u4e0b\u8f7d JDK\u2026\uff09\u6765\u4e0b\u8f7d\u5176\u4ed6\u7248\u672c\u3002 \u60a8\u53ef\u4ee5\u4ece\u4f9b\u5e94\u5546\u5217\u8868\u4e2d\u9009\u62e9\u8981\u4e0b\u8f7d\u7684 JDK \u7248\u672c\u3002<\/p>\n

\u5728 Modules\uff08\u6a21\u5757\uff09\u6807\u7b7e\u9875\u4e0a\uff0c\u786e\u4fdd\u4e3a\u6a21\u5757\u9009\u62e9\u76f8\u540c\u7684\u8bed\u8a00\u7ea7\u522b \u2013 20 (Preview) \u2013 Record patterns (second preview), Pattern Matching for switch (fourth preview)<\/i>\uff1a<\/p>\n

\"\"<\/figure>\n

\u00a0<\/p>\n

\u9009\u62e9\u6b64\u9009\u9879\u540e\uff0c\u53ef\u80fd\u4f1a\u51fa\u73b0\u4ee5\u4e0b\u5f39\u51fa\u7a97\u53e3\uff0c\u901a\u77e5\u60a8 IntelliJ IDEA \u53ef\u80fd\u4f1a\u5728\u540e\u7eed\u7248\u672c\u4e2d\u505c\u6b62\u5bf9 Java \u9884\u89c8\u8bed\u8a00\u529f\u80fd\u7684\u652f\u6301\u3002 \u56e0\u4e3a\u9884\u89c8\u529f\u80fd\u4e0d\u662f\u6c38\u4e45\u6027\u7684\uff0c\u5e76\u4e14\u53ef\u80fd\u5728\u672a\u6765\u7684 Java \u7248\u672c\u4e2d\u53d1\u751f\u53d8\u5316\uff08\u751a\u81f3\u88ab\u79fb\u9664\uff09\u3002
\u6211\u4eec\u5148\u5feb\u901f\u56de\u987e\u4e00\u4e0b Java 19 \u4e2d\u5f15\u5165\u7684\u8bb0\u5f55\u6a21\u5f0f\u3002<\/p>\n

\u00a0<\/p>\n

\u8bb0\u5f55\u6a21\u5f0f<\/h2>\n

\u5bf9\u4e8e\u8bb0\u5f55\u5b9e\u4f8b\uff0c\u60a8\u663e\u7136\u4f1a\u6267\u884c\u7684\u4e00\u9879\u64cd\u4f5c\u5c31\u662f\u63d0\u53d6\u5176\u7ec4\u4ef6\u7684\u503c\u4ee5\u4fbf\u5728\u5e94\u7528\u7a0b\u5e8f\u4e2d\u4f7f\u7528\u3002 \u8fd9\u6b63\u662f\u8bb0\u5f55\u6a21\u5f0f\u7684\u529f\u80fd\u3002<\/p>\n

\u9996\u5148\uff0c\u8ba9\u6211\u4eec\u5feb\u901f\u56de\u987e\u4e00\u4e0b\u8bb0\u5f55\u6a21\u5f0f\u662f\u4ec0\u4e48\u4ee5\u53ca\u60a8\u4e3a\u4ec0\u4e48\u9700\u8981\u5b83\u4eec\u3002<\/p>\n

\u8bb0\u5f55\u6a21\u5f0f\u5feb\u901f\u56de\u987e<\/h3>\n

\u00a0<\/p>\n

\u8bb0\u5f55\u63d0\u4f9b\u4e86\u4e00\u79cd\u7b80\u5355\u660e\u4e86\u7684\u65b9\u5f0f\u6765\u4e3a\u60a8\u7684\u6570\u636e\u521b\u5efa\u900f\u660e\u7684\u8f7d\u4f53\u3002 \u5b83\u4eec\u4f7f\u60a8\u80fd\u591f\u5c06\u591a\u4e2a\u503c\uff08\u4e5f\u79f0\u4e3a\u7ec4\u4ef6\uff09\u6c47\u603b\u5230\u4e00\u8d77\u3002 \u53e6\u4e00\u65b9\u9762\uff0c\u8bb0\u5f55\u6a21\u5f0f\u53ef\u4ee5\u5c06\u8bb0\u5f55\u5b9e\u4f8b\u5206\u89e3\u4e3a\u5176\u7ec4\u4ef6\uff0c\u4ece\u800c\u4f7f\u60a8\u80fd\u591f\u8f7b\u677e\u5730\u4f7f\u7528\u7ec4\u4ef6\u7684\u503c\u3002<\/p>\n

\u4f8b\u5982\uff0c\u5bf9\u4e8e\u4ee5\u4e0b\u8bb0\u5f55\uff1a<\/p>\n

record Name       (String fName, String lName) { }\nrecord PhoneNumber(String areaCode, String number) { }\nrecord Country    (String countryCode, String countryName) { }\nrecord Passenger  (Name name,\n                  PhoneNumber phoneNumber,\n                  Country from,\n                  Country destination) { }<\/pre>\n
\u4ee5\u4e0b\u4ee3\u7801\u6f14\u793a\u4e86\u5982\u4f55\u5c06\u8bb0\u5f55\u6a21\u5f0f\u4e0e instanceof<\/code> \u8fd0\u7b97\u7b26\u642d\u914d\u4f7f\u7528\uff0c\u5e76\u5b9a\u4e49\u7b80\u6d01\u660e\u4e86\u7684\u4ee3\u7801\u4ee5\u5c06\u8bb0\u5f55\u5b9e\u4f8b\u7684\u7ec4\u4ef6\u5206\u89e3\u4e3a\u4e00\u7ec4\u6a21\u5f0f\u53d8\u91cf\uff1a<\/p>\n
boolean checkFirstNameAndCountryCodeAgain (Object obj) {\n  if (obj instanceof Passenger(Name (String fName, var lName),\n                               var phoneNumber,\n                               Country from,\n                               Country (var countryCode, String countryName) )) {\n      if (fName != null && countryCode != null) {\n          return fName.startsWith(\"Simo\") && countryCode.equals(\"PRG\");\n      }\n  }\n  return false;\n}<\/pre>\n
\u5982\u679c\u60a8\u5bf9\u8bb0\u5f55\u6a21\u5f0f\u5b8c\u5168\u964c\u751f\uff0c\u5efa\u8bae\u60a8\u53c2\u9605\u6211\u7684\u535a\u6587 Java 19 \u548c IntelliJ IDEA<\/a>\uff0c\u5176\u4e2d\u8be6\u7ec6\u4ecb\u7ecd\u4e86\u8bb0\u5f55\u6a21\u5f0f \u2013 \u5b83\u4eec\u662f\u4ec0\u4e48\uff0c\u4e3a\u4ec0\u4e48\u4ee5\u53ca\u5982\u4f55\u4f7f\u7528\u5b83\u4eec\u3002 \u5728\u672c\u6587\u4e2d\uff0c\u6211\u5c06\u4ecb\u7ecd\u8bb0\u5f55\u6a21\u5f0f\u4ece Java 19 \u5230 Java 20 \u53d1\u751f\u7684\u53d8\u5316\u3002<\/p>\n
Java 20 \u4e0d\u518d\u4f7f\u7528\u6700\u521d\u5728 Java 19 \u4e2d\u6dfb\u52a0\u7684\u547d\u540d\u8bb0\u5f55\u6a21\u5f0f<\/a>\u3002 Java 20 \u8fd8\u6539\u8fdb\u4e86\u5bf9\u63a8\u65ad\u6cdb\u578b\u8bb0\u5f55\u7c7b\u578b\u5b9e\u53c2\u7684\u652f\u6301\uff0c\u5e76\u652f\u6301\u5728\u589e\u5f3a for<\/code> \u5faa\u73af\u8bed\u53e5\u5934\u4e2d\u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f\u3002<\/p>\n
\u00a0<\/p>\n
\u8bb0\u5f55\u7ec4\u4ef6\u7c7b\u578b\u63a8\u65ad<\/h3>\n
\u00a0<\/p>\n
Java 19 \u652f\u6301\u8bb0\u5f55\u7ec4\u4ef6\u7684\u63a8\u65ad \u2013 \u60a8\u53ef\u4ee5\u4f7f\u7528 var<\/code> \u800c\u4e0d\u662f\u8bb0\u5f55\u7ec4\u4ef6\u7684\u663e\u5f0f\u7c7b\u578b\u3002 \u6211\u4eec\u56de\u987e\u4e00\u4e0b\u4e0a\u4e00\u90e8\u5206\u4e2d\u63d0\u4f9b\u7684\u8bb0\u5f55\u6a21\u5f0f\u793a\u4f8b\uff0c\u5e76\u6ce8\u610f var<\/code> \u7684\u7528\u6cd5\uff1a<\/p>\n
boolean checkFirstNameAndCountryCodeAgain (Object obj) {\n  if (obj instanceof Passenger(Name (String fName, var lName),\n                               var phoneNumber,\n                               Country from,\n                               Country (var countryCode, String countryName) )) {\n      if (fName != null && countryCode != null) {\n          return fName.startsWith(\"Simo\") && countryCode.equals(\"PRG\");\n      }\n  }\n  return false;\n}<\/pre>\n
\u9002\u7528\u4e8e\u6240\u6709\u4f7f\u7528 var<\/code> \u5b9a\u4e49\u7684\u5c40\u90e8\u53d8\u91cf\uff0cIntelliJ IDEA \u53ef\u4ee5\u663e\u793a\u4f7f\u7528\u4fdd\u7559\u5173\u952e\u5b57 var<\/code> \u5b9a\u4e49\u7684\u53d8\u91cf\u7684\u663e\u5f0f\u7c7b\u578b\uff1a<\/p>\n
\"\"<\/figure>\n
\u00a0<\/p>\n
\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f<\/h3>\n
\u00a0<\/p>\n
Java 20 \u652f\u6301\u63a8\u65ad\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7684\u7c7b\u578b\u5b9e\u53c2\u3002 \u6211\u4eec\u4ee5\u5411\u597d\u53cb\u9001\u793c\u4e3a\u4f8b\u6765\u7406\u89e3\u8fd9\u4e00\u5185\u5bb9\uff0c\u60a8\u53ef\u80fd\u60f3\u5411\u597d\u53cb\u8d60\u9001\u624b\u8868\u6216\u4e66\u7c4d\u4e4b\u7c7b\u7684\u793c\u7269\u3002<\/p>\n
\u5047\u8bbe\u4ee5\u4e0b\u975e\u6cdb\u578b\u7c7b Book<\/code> \u548c WristWatch<\/code> \u4ee5\u53ca\u6cdb\u578b\u8bb0\u5f55 Gift<\/code> \u5b9a\u4e49\uff1a<\/p>\n
class Book {...}\nclass WristWatch {...}\nrecord Gift<T>(T t) {}<\/pre>\n
\u5f53\u60a8\u7684\u597d\u53cb\u6536\u5230\u60a8\u7684\u793c\u7269\u5e76\u8bd5\u56fe\u89e3\u5f00\u793c\u7269\u5305\u88c5\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1f \u5047\u8bbe\u4ed6\u4eec\u8c03\u7528\u4e0b\u65b9\u5b9a\u4e49\u7684\u89e3\u5305\u65b9\u6cd5\u3002 \u5728\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u65b9\u6cd5 unwrap<\/code> \u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f Gift<wristwatch> (var watch)<\/code>\u3002 \u7531\u4e8e\u6b64\u6a21\u5f0f\u5df2\u7ecf\u4f7f\u7528\u8bb0\u5f55\u540d\u79f0 Gift<\/code> \u6307\u5b9a\u4e86\u6cdb\u578b\u7c7b\u578b WristWatch<\/code>\uff0c\u6a21\u5f0f\u53d8\u91cf watch<\/code> \u53ef\u88ab\u63a8\u65ad\u4e3a\u7c7b\u578b WristWatch<\/code>\uff1a<\/p>\n
void unwrap(Gift<wristwatch> obj) {\n   if (obj instanceof Gift<wristwatch> (var watch)) {\n       watch.setAlarm(LocalTime.of(10, 25));\n   }\n}<\/pre>\n
\u4ee5\u4e0b\u793a\u4f8b\u5728 Java 19 \u4e2d\u4e0d\u8d77\u4f5c\u7528\uff0c\u4f46\u5728 Java 20 \u4e2d\u53ef\u4ee5\uff1a<\/p>\n
void unwrapAndRevealSurprise(Gift<WristWatch> obj) {\n    if (obj instanceof Gift<WristWatch> (var watch)) {\n        System.out.println(watch);\n    }\n}\n\nvoid unwrapAndUseGift(Gift<WristWatch> obj) {\n    if (obj instanceof Gift(var gift)) {\n        gift.setAlarmTime(LocalTime.now());\n    }\n}\n\nvoid birthdayGift(Gift<DiamondStudded<WristWatch>> gift) {\n    if (gift instanceof Gift<DiamondStudded<WristWatch>>(DiamondStudded(var personalizedGift))) {\n        System.out.println(personalizedGift);\n    }\n}\n\nvoid performanceBonus(Gift<DiamondStudded<WristWatch>> personalizedGift) {\n    if (personalizedGift instanceof Gift(DiamondStudded(var actualGift))) {\n        System.out.println(\"Wrist watch\" + actualGift);\n    }\n}<\/pre>\n
\u8ba9\u6211\u4eec\u5728\u4e0b\u4e00\u90e8\u5206\u4e2d\u4e86\u89e3\u8fd9\u4f1a\u5982\u4f55\u6539\u53d8\u8be6\u5c3d switch \u6784\u9020\u7684\u5de5\u4f5c\u65b9\u5f0f\u3002<\/p>\n
\u00a0<\/p>\n
\u8be6\u5c3d switch \u6784\u9020\u4e0e\u6cdb\u578b\u8bb0\u5f55<\/h3>\n
\u00a0<\/p>\n
\u5f00\u59cb\u4e4b\u524d\uff0c\u6211\u4eec\u5148\u6765\u68b3\u7406\u4e00\u4e0b\u57fa\u7840\u77e5\u8bc6\u3002 \u4e0b\u56fe\u5c55\u793a\u4e86\u9009\u62e9\u5668\u8868\u8fbe\u5f0f\u5728 switch \u8bed\u53e5\u6216 switch \u8868\u8fbe\u5f0f\u4e2d\u5f15\u7528\u7684\u5185\u5bb9\uff08\u4f20\u9012\u7ed9 switch \u6784\u9020\u7684\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\uff09\uff1a<\/p>\n
\"\"<\/figure>\n
switch \u8bed\u53e5\u548c switch \u8868\u8fbe\u5f0f\u7684\u8bed\u6cd5\u89c4\u5b9a\uff0c\u5f53\u60a8\u5c1d\u8bd5\u5c06\u9009\u62e9\u5668\u8868\u8fbe\u5f0f\u7684\u503c\u4e0e\u5176 case \u6807\u7b7e\u4e2d\u7684\u7c7b\u578b\u6a21\u5f0f\u6216\u8bb0\u5f55\u6a21\u5f0f\u76f8\u5339\u914d\u65f6\uff0c\u5b83\u5fc5\u987b\u662f\u8be6\u5c3d\u7684\u3002 \u6362\u53e5\u8bdd\u8bf4\uff0c\u9009\u62e9\u5668\u8868\u8fbe\u5f0f\u5fc5\u987b\u81f3\u5c11\u4e0e case \u6807\u7b7e\u4e2d\u5b9a\u4e49\u7684\u4e00\u4e2a\u503c\u76f8\u5339\u914d\u3002<\/p>\n
\u5bf9\u4e8e\u8bf8\u5982 Object<\/code> \u7c7b\u578b\u8fd9\u79cd\u5b50\u7c7b\u578b\u6570\u91cf\u4e0d\u786e\u5b9a\u7684\u7c7b\u578b\uff08\u5373\u6269\u5c55\u8be5\u7c7b\u578b\u7684\u5176\u4ed6\u7c7b\u7684\u6570\u91cf\u4e0d\u56fa\u5b9a\uff09\uff0c\u60a8\u53ef\u4ee5\u5b9a\u4e49 default<\/code> case \u6807\u7b7e\u6216 Object<\/code> \u7c7b\u578b\u672c\u8eab\u4f5c\u4e3a case \u6807\u7b7e\u4e4b\u4e00\uff0c\u4ece\u800c\u4f7f\u5176\u6210\u4e3a\u8be6\u5c3d switch \u6784\u9020\u3002 \u4ee5\u4e0b\u662f\u8be6\u5c3d switch \u8868\u8fbe\u5f0f\u548c\u8be6\u5c3d switch \u8bed\u53e5\u7684\u6709\u6548\u793a\u4f8b\uff1a<\/p>\n
String exhaustiveSwitchExpression(Object obj) {\n   return switch (obj) {\n       case String s -> \"String\";\n       case Apple apple -> \"Apple\";\n       default -> \"everything else\";\n   };\n}\n\nvoid exhaustiveSwitchStatement(Object obj) {\n   switch (obj) {\n       case String s -> System.out.println(\"String\");\n       case Apple apple -> System.out.println(\"Apple\");\n       case Object object -> System.out.println(\"everything else\");\n   };\n}<\/pre>\n
\u67d0\u4e9b\u7c7b\u578b\uff08\u5982\u5bc6\u5c01\u7c7b\uff09\u5177\u6709\u660e\u786e\u7684\u5b50\u7c7b\u578b\uff0c\u56e0\u6b64\u60a8\u53ef\u80fd\u4e0d\u9700\u8981 default<\/code> \u6807\u7b7e\u5373\u53ef\u5b9a\u4e49\u8be6\u5c3d switch \u8bed\u53e5\u6216 switch \u8868\u8fbe\u5f0f\u3002 \u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n
sealed interface HighProtein permits Egg, Cheese {}\nfinal class Egg implements HighProtein {}\nfinal class Cheese implements HighProtein {}\n \nint processHighProtein(HighProtein protein) {\n   return switch (protein) {\n       case Egg egg -> 2;\n       case Cheese cheese -> 10;\n   };\n}<\/pre>\n
\u4f46\u662f\uff0c\u5982\u679c\u60a8\u5c06\u63a5\u53e3 HighProtein<\/code> \u5b9a\u4e49\u4e3a\u5e38\u89c4\u63a5\u53e3\uff0c\u4e5f\u5c31\u662f\u975e\u5bc6\u5c01\u63a5\u53e3\uff0c\u90a3\u4e48\u4e0a\u9762\u7684\u4ee3\u7801\u5c31\u65e0\u6cd5\u7f16\u8bd1\u3002<\/p>\n
\u73b0\u5728\uff0c\u6211\u4eec\u6765\u804a\u4e00\u804a\u5982\u679c\u9009\u62e9\u5668\u8868\u8fbe\u5f0f\u4e3a\u6cdb\u578b\u8bb0\u5f55\uff0c\u5b83\u4e0e\u8bb0\u5f55\u6a21\u5f0f\u5339\u914d\u65f6\u5982\u4f55\u5b9a\u4e49\u8be6\u5c3d case \u6807\u7b7e\u3002 \u4ee5\u4e0b\u662f\u4e00\u4e2a\u6cdb\u578b\u7c7b Apple<\/code> \u7684\u793a\u4f8b\uff0c\u5b83\u88ab\u4ee5\u4e0b\u5185\u5bb9\u6269\u5c55\uff1a\u53e6\u4e00\u4e2a\u7c7b HimalayanApple<\/code>\u3001\u7531\u7c7b Egg<\/code> \u548c Cheese<\/code> \u5b9e\u73b0\u7684\u5bc6\u5c01\u63a5\u53e3 HighProtein<\/code>\uff0c\u4ee5\u53ca\u63a5\u53d7\u7c7b\u578b\u5f62\u53c2\u5e76\u5b9a\u4e49\u8be5\u7c7b\u578b\u7684\u4e24\u4e2a\u7ec4\u4ef6\u7684\u6cdb\u578b\u8bb0\u5f55 Dish<\/code>\uff1a<\/p>\n
public class Apple {}\npublic class HimalayanApple extends Apple{}\n\nsealed public interface HighProtein permits Egg, Cheese {}\npublic final class Egg implements HighProtein {}\npublic final class Cheese implements HighProtein {}\n\npublic record Dish<T> (T x, T y){}<\/pre>\n
\u6211\u4eec\u6765\u804a\u4e00\u804a\u60a8\u5728\u5207\u6362\u6b64\u6cdb\u578b\u8bb0\u5f55\u7c7b Dish<\/code> \u7684\u5b9e\u4f8b\u65f6\u53ef\u4ee5\u4f7f\u7528\u6216\u4e0d\u53ef\u4ee5\u4f7f\u7528\u7684\u591a\u79cd\u7ec4\u5408\u3002<\/p>\n
\u8ba9\u6211\u4eec\u4ece\u65b9\u6cd5\u5f00\u59cb\uff0c\u4f8b\u5982 orderAppleDish<\/code>\uff0c\u5b83\u63a5\u53d7 Dish<Apple> appleDish<\/code> \u7c7b\u578b\u7684\u65b9\u6cd5\u5f62\u53c2\u5e76\u8fdb\u884c\u5207\u6362\uff0c\u8fdb\u800c\u4e0e\u8bb0\u5f55\u6a21\u5f0f\u76f8\u5339\u914d\u3002 \u60a8\u8ba4\u4e3a\u4ee5\u4e0b\u4ee3\u7801\u662f\u5426\u53ef\u884c\uff1a<\/p>\n
    int orderAppleDish(Dish<Apple> appleDish) {\n        return switch (appleDish) {\n            case Dish<Apple>(Apple apple, HimalayanApple himalayanApple) -> 1;\n            case Dish<Apple>(HimalayanApple himalayanApple, Apple apple) -> 2;\n        };\n    }<\/pre>\n
\u7531\u4e8e HimalayanApple<\/code> \u7c7b\u6269\u5c55 Apple<\/code> \u7c7b\uff0c\u9700\u8981\u4ee5\u4e0b\u4e24\u79cd\u7ec4\u5408\u624d\u80fd\u4f7f\u524d\u9762\u7684 switch \u8868\u8fbe\u5f0f\u6210\u4e3a\u8be6\u5c3d switch\uff1a<\/p>\n
Apple, Apple
HimalayanApple, HimalayanApple<\/p>\n
\u4ee5\u4e0b GIF \u56fe\u5c55\u793a\u4e86 IntelliJ IDEA \u5982\u4f55\u68c0\u6d4b\u5230\u524d\u9762\u7684\u4ee3\u7801\u5b58\u5728\u95ee\u9898\u5e76\u5e2e\u52a9\u60a8\u5bfc\u822a\u4ee3\u7801\u5e76\u66f4\u6b63\u9519\u8bef\uff1a<\/p>\n
\"\"<\/figure>\n
\u4ee5\u4e0b\u662f\u4e0a\u65b9 gif \u4e2d\u7684\u6700\u7ec8\u4ee3\u7801\uff0c\u4f9b\u60a8\u53c2\u8003\uff1a<\/p>\n
class Apple {}\nclass HimalayanApple extends Apple{}\nrecord Dish<T> (T ingredient1, T ingredient2) {}\n\npublic class FoodOrder {\n\n    int orderAppleDish(Dish<Apple> appleDish) {\n        return switch (appleDish) {\n            case Dish<Apple>(HimalayanApple apple1, HimalayanApple apple2) -> 4;\n            case Dish<Apple>(Apple apple, HimalayanApple himalayanApple) -> 1;\n            case Dish<Apple>(HimalayanApple himalayanApple, Apple apple) -> 2;\n            case Dish<Apple>(Apple apple1, Apple apple2) -> 3;\n        };\n    }\n\n}<\/pre>\n
\u6211\u4eec\u6765\u770b\u53e6\u4e00\u4e2a\u793a\u4f8b\uff0c\u5b83\u5c06\u4ee5\u4e0b\u5bc6\u5c01\u63a5\u53e3\u53ca\u5176\u5b9e\u73b0\u4e0e\u6cdb\u578b\u8bb0\u5f55 Dish<\/code> \u7ed3\u5408\u4f7f\u7528\uff1a<\/p>\n
sealed public interface HighProtein permits Egg, Cheese {}\npublic final class Egg implements HighProtein {}\npublic final class Cheese implements HighProtein {}\n\npublic record Dish<T> (T x, T y){}<\/pre>\n
\u60f3\u8c61\u4e00\u4e2a\u4eba\u5728\u70b9\u83dc\uff0c\u4ed6\u4f20\u9012\u4e86\u4e00\u4e2a Dish<\/code> \u5b9e\u4f8b\uff0c\u4ee5\u63a5\u53e3 HighProtein<\/code> \u4f5c\u4e3a\u5176\u7c7b\u578b\u5f62\u53c2\u3002 \u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4ee5\u4e0b switch \u8868\u8fbe\u5f0f\u4e3a\u8be6\u5c3d\uff1a<\/p>\n
\"\"<\/figure>\n
\u4ee5\u4e0b\u4ee3\u7801\u4f9b\u60a8\u53c2\u8003\uff1a<\/p>\n
public class FoodOrder {\n\n    int orderHighProteinDish(Dish<HighProtein> proteinDish) {\n        return switch (proteinDish) {\n            case Dish<HighProtein>(HighProtein protein, Egg egg) -> 1;\n            case Dish<HighProtein>(HighProtein protein, Cheese cheese) -> 2;\n        };\n    }\n\n}<\/pre>\n
\u7531\u4e8e HighProtein<\/code> \u662f\u4e00\u4e2a\u5bc6\u5c01\u63a5\u53e3\uff0c\u4ee5\u4e0b switch \u6784\u9020\u4e2d\u7684\u7b2c\u4e00\u4e2a case \u6807\u7b7e\u6db5\u76d6\u4e86\u5c06 Egg<\/code> \u6216 Cheese<\/code> \u4f5c\u4e3a\u7b2c\u4e8c\u4e2a\u503c\u4f20\u9012\u7ed9\u8bb0\u5f55 Dish \u7684\u53ef\u80fd\u6027\u3002 \u56e0\u6b64\uff0c\u5373\u4f7f\u4ec5\u5b9a\u4e49\u4e86\u4e09\u4e2a case \u6807\u7b7e\uff0c\u5b83\u4e5f\u662f\u8be6\u5c3d switch \u8868\u8fbe\u5f0f\uff1a<\/p>\n
public class FoodOrder {\n\n    int orderHighProteinDish(Dish<HighProtein> proteinDish) {\n        return switch (proteinDish) {\n            case Dish<HighProtein>(Egg protein, HighProtein highProtein) -> 1;\n            case Dish<HighProtein>(Cheese cheese, Egg egg) -> 2;\n            case Dish<HighProtein>(Cheese cheese1, Cheese cheese2) -> 4;\n        };\n    }\n\n}<\/pre>\n
\u5728\u5173\u4e8e\u8be6\u5c3d switch \u548c\u6cdb\u578b\u8bb0\u5f55\u7684\u6700\u540e\u4e00\u4e2a\u793a\u4f8b\u4e2d\uff0cswitch \u8868\u8fbe\u5f0f\u4e2d\u7684\u4ee5\u4e0b\u521d\u59cb case \u6807\u7b7e\u96c6\u5e76\u4e0d\u8be6\u5c3d\uff0c\u56e0\u4e3a\u5b83\u4e0d\u5305\u542b\u7aef\u4e0a\u4e00\u9053\u7b2c\u4e00\u79cd\u539f\u6599\u4e3a HighProtein<\/code> \u7684\u5b9e\u4f8b\u4ee5\u53ca\u7b2c\u4e8c\u4e2a\u503c\u4e3a Egg<\/code> \u7684\u5b9e\u4f8b\u7684\u9ad8\u86cb\u767d\u83dc\u80b4\u7684\u53ef\u80fd\u6027\uff1a<\/p>\n
    int orderHighProteinDish(Dish<HighProtein> proteinDish) {\n        return switch (proteinDish) {\n            case Dish<HighProtein>(Egg protein, Cheese cheese) -> 1;\n            case Dish<HighProtein>(Cheese cheese, Egg egg) -> 2;\n            case Dish<HighProtein>(HighProtein highProtein, Cheese cheese) -> 3;\n        };\n    }\n<\/pre>\n
\u8ba9\u6211\u4eec\u5728\u524d\u9762\u7684\u4ee3\u7801\u4e2d\u6dfb\u52a0\u53e6\u4e00\u4e2a case \u6807\u7b7e\uff0c\u4f7f\u5176\u6210\u4e3a\u8be6\u5c3d switch \u8868\u8fbe\u5f0f\uff1a<\/p>\n
            case Dish<HighProtein>(HighProtein highProtein, Egg egg) -> 10;<\/pre>\n
\u00a0<\/p>\n
\u5c06\u8bb0\u5f55\u6a21\u5f0f\u4e0e\u589e\u5f3a for \u8bed\u53e5\u7ed3\u5408\u4f7f\u7528<\/h3>\n
\u00a0<\/p>\n
\u4f7f\u7528 Java 20\uff0c\u60a8\u53ef\u4ee5\u5728\u589e\u5f3a for<\/code> \u5faa\u73af\u8bed\u53e5\u5934\u4e2d\u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f\u3002 \u4f46\u662f\uff0c\u5bf9\u4e8e\u53ef\u4ee5\u5728\u5176\u4e2d\u6307\u5b9a\u591a\u4e2a case \u6807\u7b7e\u7684 switch \u8bed\u53e5\u6216\u8868\u8fbe\u5f0f\uff0c\u60a8\u5728\u589e\u5f3a for \u5faa\u73af\u8bed\u53e5\u5934\u4e2d\u4f7f\u7528\u7684\u5355\u4e2a\u8bb0\u5f55\u6a21\u5f0f\u5fc5\u987b\u4e0e\u60a8\u5728 for \u5faa\u73af\u4e2d\u904d\u5386\u7684\u6240\u6709\u503c\u76f8\u5339\u914d\u3002 \u5426\u5219\uff0c\u60a8\u7684\u4ee3\u7801\u5c06\u629b\u51fa\u8fd0\u884c\u65f6\u5f02\u5e38\u3002<\/p>\n
\u4ee5\u4e0b\u793a\u4f8b\u91c7\u7528\u4e86 Point<\/code> \u548c Triangle<\/code> \u8bb0\u5f55\u4ee5\u53ca\u589e\u5f3a for \u5faa\u73af\uff0c\u540e\u8005\u5728\u5176\u8bed\u53e5\u5934\u4e2d\u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f\u6765\u904d\u5386 Triangle<\/code> \u5b9e\u4f8b\u7684\u5217\u8868\uff1a<\/p>\n
record Point (int x, int y) { }\nrecord Triangle(Point pointA, Point pointB, Point PointC) { }\n\nlong addLowerRightCoordinates(List<Triangle> triangles) {\n    long sum = 0;\n    for (Triangle(Point a, Point b, Point (int x, int y)) : triangles) {\n        sum += x + y;\n    }\n    return sum;\n}<\/pre>\n
\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4e0d\u6b63\u786e\u7684\u793a\u4f8b\uff1a<\/p>\n
public class Test {\n\n    sealed interface UpperWithPermit permits PermittedRecord {}\n    record PermittedRecord(int x) implements UpperWithPermit {}\n    interface Upper {}\n    record Record(List<String> x) implements Upper {}\n\n    void test1(List<Upper> lists) {\n        for (Record(List<String> x) : lists) {} \n    }\n\n    void test2(List<? super UpperWithPermit> lists) {\n        for (PermittedRecord(var x) : lists) {} \n    }\n\n    void test3(List<? super PermittedRecord> lists) {\n        for (PermittedRecord(var x) : lists) {} \n    }\n\n    void test4(List lists) {\n        for (PermittedRecord(var x) : lists) {} \n    }\n\n    void test5(List<?> lists) {\n        for (PermittedRecord(var x) : lists) {} \n    }\n}<\/pre>\n
\u00a0<\/p>\n
switch \u7684\u6a21\u5f0f\u5339\u914d<\/h2>\n
\u5728 Java 20 \u4e2d\uff0cswitch \u7684\u6a21\u5f0f\u5339\u914d\u5df2\u8fdb\u5165\u7b2c\u56db\u4e2a\u9884\u89c8\u7248\u9636\u6bb5\u3002 \u5982\u679c\u60a8\u5bf9\u6a21\u5f0f\u5339\u914d\u5b8c\u5168\u964c\u751f\uff0c\u5efa\u8bae\u60a8\u53c2\u89c1\u6b64\u94fe\u63a5<\/a>\u6765\u9996\u5148\u4e86\u89e3 instanceof \u6a21\u5f0f\u5339\u914d\u3002 \u5982\u679c\u60a8\u5c1a\u4e0d\u719f\u6089 switch \u7684\u6a21\u5f0f\u5339\u914d\uff0c\u8bf7\u53c2\u89c1\u6b64\u94fe\u63a5<\/a>\u3002<\/p>\n
Java 20 \u4e2d\u5bf9\u6b64\u529f\u80fd\u8fdb\u884c\u4e86\u4e00\u4e9b\u66f4\u6539\u3002 \u4e0e\u679a\u4e3e\u7c7b\u7ed3\u5408\u4f7f\u7528\u65f6\uff0c\u5982\u679c\u8be6\u5c3d switch \u8bed\u53e5\u6216 switch \u8868\u8fbe\u5f0f\u5728\u8fd0\u884c\u65f6\u627e\u4e0d\u5230\u5339\u914d\u7684\u6807\u7b7e\uff0c\u5219 switch \u7684\u6a21\u5f0f\u5339\u914d\u73b0\u5728\u4f1a\u629b\u51fa MatchException<\/code>\uff0c\u800c\u4e0d\u662f\u629b\u51fa ImcompatibleClassChangeError<\/code>\u3002 Java 20 \u4e2d\u6b64\u529f\u80fd\u7684\u53e6\u4e00\u4e2a\u53d8\u5316\u662f\u5173\u4e8e case \u6807\u7b7e\u4e2d\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7684\u7c7b\u578b\u5f62\u53c2\u63a8\u65ad\u3002 \u6211\u5df2\u7ecf\u5728\u8fd9\u7bc7\u535a\u6587\u7684 \u8be6\u5c3d switch \u6784\u9020\u4e0e\u6cdb\u578b\u8bb0\u5f55<\/a>\u90e8\u5206\u4e2d\u4ecb\u7ecd\u4e86\u6b64\u529f\u80fd\u3002<\/p>\n
\u603b\u7ed3<\/h2>\n
\u00a0<\/p>\n
IntelliJ IDEA \u7ee7\u7eed\u964d\u4f4e\u5f00\u53d1\u8005\u4f7f\u7528\u6700\u65b0 Java \u529f\u80fd\u7684\u8ba4\u77e5\u8d1f\u62c5\u3002 IntelliJ IDEA 2023.1 \u652f\u6301 Java 20 \u4e2d\u6dfb\u52a0\u7684\u5bf9\u201cswitch \u7684\u6a21\u5f0f\u5339\u914d\u201d\u548c\u201c\u8bb0\u5f55\u6a21\u5f0f\u201d\u7b49\u8bed\u8a00\u529f\u80fd\u7684\u66f4\u6539\u3002 \u8fd9\u4e9b\u529f\u80fd\u4e2d\u6700\u6709\u8da3\u7684\u53d8\u5316\u662f\u652f\u6301\u5728\u589e\u5f3a for \u8bed\u53e5\u5934\u4e2d\u4f7f\u7528\u8bb0\u5f55\u6a21\u5f0f\uff0c\u4ee5\u53ca\u6539\u8fdb\u4e86\u6cdb\u578b\u8bb0\u5f55\u6a21\u5f0f\u7c7b\u578b\u5b9e\u53c2\u7684\u7c7b\u578b\u63a8\u65ad\u3002<\/p>\n
\u5feb\u4e50\u7f16\u7a0b\uff01<\/p>\n
\u00a0<\/p>\n
\u672c\u535a\u6587\u82f1\u6587\u539f\u4f5c\u8005\uff1a<\/p>\n\n    
\n        
\n            
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