{"id":753,"date":"2024-02-26T11:36:49","date_gmt":"2022-11-22T04:49:57","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/index.php\/2023\/11\/30\/java-12-%e7%89%b9%e6%80%a7\/"},"modified":"2025-08-03T06:23:13","modified_gmt":"2025-08-02T22:23:13","slug":"java-12-%e7%89%b9%e6%80%a7","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/java-12-%e7%89%b9%e6%80%a7\/","title":{"rendered":"Java 12\u65b0\u7279\u6027\u5168\u9762\u89e3\u6790\uff1a\u5f00\u53d1\u8005\u5fc5\u77e5\u7684\u529f\u80fd\u6539\u8fdb\u4e0e\u5e94\u7528\u6280\u5de7"},"content":{"rendered":"

\u6700\u7ec8\uff0cJDK 12\u4f5c\u4e3a\u516d\u4e2a\u6708\u53d1\u5e03\u5468\u671f\u7684\u4e00\u90e8\u5206\u5df2\u7ecf\u53d1\u5e03\u4e86\u3002\u5b83\u662f\u7ee7\u4e0a\u4e00\u4e2aJava LTS\u7248\u672c11\u4e4b\u540e\u63a8\u51fa\u7684\u3002\u6211\u4eec\u4e4b\u524d\u8be6\u7ec6\u8ba8\u8bba\u8fc7Java 11\u7684\u7279\u6027\u3002\u4eca\u5929\u6211\u4eec\u5c06\u8ba8\u8bbaJava 12\u7684\u7279\u6027\uff0c\u5e76\u770b\u770b\u5b83\u4e3a\u5f00\u53d1\u8005\u5e26\u6765\u4e86\u4ec0\u4e48\u3002Java 12\u4e8e2019\u5e743\u670819\u65e5\u53d1\u5e03\uff0c\u5b83\u662f\u4e00\u4e2a\u975eLTS\u7248\u672c\uff0c\u56e0\u6b64\u4e0d\u4f1a\u83b7\u5f97\u957f\u671f\u652f\u6301\u3002<\/p>\n

Java 12\u7684\u529f\u80fd<\/h2>\n

Java 12\u7684\u4e00\u4e9b\u91cd\u8981\u529f\u80fd\u5305\u62ec\uff1a<\/p>\n

    \n
  1. JVM\u53d8\u52a8 – JEP 189\u3001JEP 346\u3001JEP 344 \u548c JEP 230\u3002<\/li>\n
  2. \u5207\u6362\u8868\u8fbe\u5f0f<\/li>\n
  3. \u6587\u4ef6mismatch()\u65b9\u6cd5<\/li>\n
  4. \u7d27\u51d1\u6570\u5b57\u683c\u5f0f<\/li>\n
  5. \u6d41API\u4e2d\u7684\u5408\u5e76\u6536\u96c6\u5668<\/li>\n
  6. Java\u5b57\u7b26\u4e32\u65b0\u65b9\u6cd5 – indent()\u3001transform()\u3001describeConstable() \u548c resolveConstantDesc()\u3002<\/li>\n
  7. JEP 334: JVM\u5e38\u91cfAPI<\/li>\n
  8. JEP 305: instanceof\u7684\u6a21\u5f0f\u5339\u914d<\/li>\n
  9. \u539f\u59cb\u5b57\u7b26\u4e32\u5b57\u9762\u91cf\u4eceJDK 12\u4e2d\u79fb\u9664\u3002<\/li>\n<\/ol>\n

    \u8ba9\u6211\u4eec\u9010\u4e00\u63a2\u7a76\u6240\u6709Java 12\u7684\u7279\u6027\u3002<\/p>\n

    JVM \u53d8\u52a8<\/h2>\n

    1. JEP 189 – Shenandoah\uff1a\u4e00\u79cd\u4f4e\u505c\u987f\u65f6\u95f4\u5783\u573e\u56de\u6536\u5668\uff08\u5b9e\u9a8c\u6027\uff09<\/h3>\n

    RedHat\u53d1\u8d77\u4e86Shenandoah\u5783\u573e\u6536\u96c6\u5668\uff0c\u4ee5\u51cf\u5c11GC\u6682\u505c\u65f6\u95f4\u3002\u5176\u7406\u5ff5\u662f\u4e0e\u6b63\u5728\u8fd0\u884c\u7684Java\u7ebf\u7a0b\u5e76\u53d1\u8fd0\u884cGC\uff0c\u65e8\u5728\u65e0\u8bba\u5806\u5927\u5c0f\u5982\u4f55\u4fdd\u6301\u4e00\u81f4\u4e14\u53ef\u9884\u6d4b\u7684\u77ed\u6682\u6682\u505c\u3002\u56e0\u6b64\uff0c\u5806\u5927\u5c0f\u662f15MB\u8fd8\u662f15GB\u5e76\u4e0d\u91cd\u8981\u3002\u8fd9\u662fJava 12\u4e2d\u7684\u4e00\u4e2a\u5b9e\u9a8c\u6027\u7279\u6027\u3002<\/p>\n

    2. JEP 346 – G1\u53ca\u65f6\u5f52\u8fd8\u672a\u4f7f\u7528\u7684\u5df2\u5206\u914d\u5185\u5b58<\/h3>\n

    \u5728 Java 12 \u4e2d\uff0cG1 \u5c06\u5728\u5e94\u7528\u7a0b\u5e8f\u975e\u6d3b\u52a8\u65f6\u68c0\u67e5 Java \u5806\u5185\u5b58\uff0c\u5e76\u5c06\u5176\u5f52\u8fd8\u7ed9\u64cd\u4f5c\u7cfb\u7edf\u3002\u8fd9\u662f\u4e00\u9879\u9884\u9632\u6027\u63aa\u65bd\uff0c\u4ee5\u8282\u7ea6\u548c\u4f7f\u7528\u7a7a\u95f2\u5185\u5b58\u3002<\/p>\n

    3. JEP 344\uff1a\u53ef\u4e2d\u6b62\u6df7\u5408\u96c6\u5408\u7528\u4e8eG1\u3002<\/h3>\n

    G1\u6548\u7387\u7684\u6539\u8fdb\u5305\u62ec\u4f7f\u5f97G1\u6df7\u5408\u6536\u96c6\u53ef\u4ee5\u5728\u8d85\u8fc7\u5b9a\u4e49\u7684\u6682\u505c\u76ee\u6807\u65f6\u4e2d\u6b62\u3002\u8fd9\u662f\u901a\u8fc7\u5c06\u6df7\u5408\u6536\u96c6\u96c6\u5408\u5206\u5272\u4e3a\u5f3a\u5236\u6027\u548c\u53ef\u9009\u6027\u6765\u5b9e\u73b0\u7684\u3002\u56e0\u6b64\uff0cG1\u6536\u96c6\u5668\u53ef\u4ee5\u4f18\u5148\u6536\u96c6\u5f3a\u5236\u6027\u96c6\u5408\u4ee5\u8fbe\u5230\u6682\u505c\u65f6\u95f4\u76ee\u6807\u3002<\/p>\n

    4. JEP 230\u548c344<\/h3>\n

    \u5fae\u57fa\u51c6\u5957\u4ef6\uff0cJEP 230\u529f\u80fd\u5728JDK\u6e90\u4ee3\u7801\u4e2d\u6dfb\u52a0\u4e86\u4e00\u4e2a\u57fa\u672c\u7684\u5fae\u57fa\u51c6\u5957\u4ef6\u3002\u8fd9\u4f7f\u5f00\u53d1\u4eba\u5458\u80fd\u591f\u8f7b\u677e\u8fd0\u884c\u73b0\u6709\u7684\u5fae\u57fa\u51c6\u5e76\u521b\u5efa\u65b0\u7684\u57fa\u51c6\u3002JEP 344\u53ea\u4fdd\u7559\u4e86\u4e0e32\u4f4dARM\u7aef\u53e3\u548c64\u4f4daarch64\u7aef\u53e3\u76f8\u5173\u7684\u6e90\u4ee3\u7801\uff0c\u79fb\u9664\u4e86\u4e0earm64\u7aef\u53e3\u76f8\u5173\u7684\u6240\u6709\u6e90\u4ee3\u7801\u3002\u8fd9\u4f7f\u5f97\u8d21\u732e\u8005\u80fd\u591f\u5c06\u7cbe\u529b\u96c6\u4e2d\u5728\u5355\u4e2a64\u4f4dARM\u5b9e\u73b0\u4e0a\u3002<\/p>\n

    5. JEP 341 \u9ed8\u8ba4 CDS \u5f52\u6863<\/h3>\n

    \u8fd9\u4e2a\u589e\u5f3a\u4e86JDK\u6784\u5efa\u8fc7\u7a0b\uff0c\u7528\u4e8e\u572864\u4f4d\u5e73\u53f0\u4e0a\u751f\u6210\u4e00\u4e2a\u4f7f\u7528\u9ed8\u8ba4\u7c7b\u5217\u8868\u7684\u7c7b\u6570\u636e\u5171\u4eab\uff08CDS\uff09\u5b58\u6863\u3002\u76ee\u6807\u662f\u63d0\u9ad8\u542f\u52a8\u65f6\u95f4\u3002\u4eceJava 12\u5f00\u59cb\uff0c\u9ed8\u8ba4\u60c5\u51b5\u4e0bCDS\u662f\u5f00\u542f\u7684\u3002\u5982\u679c\u8981\u5173\u95edCDS\u5e76\u8fd0\u884c\u7a0b\u5e8f\uff0c\u8bf7\u6309\u4ee5\u4e0b\u6b65\u9aa4\u64cd\u4f5c\u3002<\/p>\n

    java -Xshare:off HelloWorld.java\r\n<\/code><\/pre>\n
    \u73b0\u5728\uff0c\u8fd9\u4f1a\u5ef6\u8fdf\u7a0b\u5e8f\u7684\u542f\u52a8\u65f6\u95f4\u3002<\/p>\n
    \u8bed\u8a00\u7684\u53d8\u5316\u548c\u7279\u70b9<\/h2>\n
    Java 12\u5f15\u5165\u4e86\u8bb8\u591a\u8bed\u8a00\u7279\u6027\uff0c\u8ba9\u6211\u4eec\u6765\u770b\u4e00\u4e9b\u5177\u4f53\u7684\u5b9e\u73b0\u3002<\/p>\n
    1. \u5f00\u5173\u8868\u8fbe\u5f0f\uff08\u9884\u89c8\u7248\uff09<\/h3>\n
    Java 12\u5bf9\u6a21\u5f0f\u5339\u914d\u7684Switch\u8868\u8fbe\u5f0f\u8fdb\u884c\u4e86\u52a0\u5f3a\u3002\u8fd9\u4e2a\u65b0\u7684\u8bed\u6cd5\u662f\u5728JEP 325\u4e2d\u5f15\u5165\u7684\uff0c\u4f5c\u4e3a\u4e00\u79cd\u9884\u89c8\u8bed\u8a00\u7279\u6027\u3002\u4ee5\u4e0b\u662f\u5173\u4e8eSwitch\u8868\u8fbe\u5f0f\u9700\u8981\u6ce8\u610f\u7684\u4e00\u4e9b\u4e8b\u9879\uff1a<\/p>\n
      \n
    • \u65b0\u8bed\u6cd5\u6d88\u9664\u4e86\u4f7f\u7528break\u8bed\u53e5\u6765\u9632\u6b62fallthroughs\u7684\u9700\u8981\u3002<\/li>\n
    • Switch\u8868\u8fbe\u5f0f\u4e0d\u518d\u53d1\u751ffallthrough\u3002<\/li>\n
    • \u6b64\u5916\uff0c\u6211\u4eec\u53ef\u4ee5\u5728\u540c\u4e00\u6807\u7b7e\u4e2d\u5b9a\u4e49\u591a\u4e2a\u5e38\u91cf\u3002<\/li>\n
    • \u5728Switch\u8868\u8fbe\u5f0f\u4e2d\uff0cdefault case\u73b0\u5728\u662f\u5f3a\u5236\u6027\u7684\u3002<\/li>\n
    • \u5728Switch\u8868\u8fbe\u5f0f\u4e2d\uff0cbreak\u7528\u4e8e\u4ececase\u672c\u8eab\u8fd4\u56de\u503c\u3002<\/li>\n<\/ul>\n
      \u7ecf\u5178\u7684switch\u8bed\u53e5\uff1a<\/p>\n
      String result = \"\";\r\n        switch (day) {\r\n            case \"M\":\r\n            case \"W\":\r\n            case \"F\": {\r\n                result = \"MWF\";\r\n                break;\r\n            }\r\n            case \"T\":\r\n            case \"TH\":\r\n            case \"S\": {\r\n                result = \"TTS\";\r\n                break;\r\n            }\r\n        };\r\n\r\n        System.out.println(\"Old Switch Result:\");\r\n        System.out.println(result);\r\n<\/code><\/pre>\n
      \u6709\u4e86\u65b0\u7684Switch\u8868\u8fbe\u5f0f\uff0c\u6211\u4eec\u4e0d\u9700\u8981\u5728\u6bcf\u4e2a\u5730\u65b9\u8bbe\u7f6ebreak\uff0c\u4ece\u800c\u9632\u6b62\u903b\u8f91\u9519\u8bef\uff01<\/p>\n
      String result = switch (day) {\r\n            case \"M\", \"W\", \"F\" -> \"MWF\";\r\n            case \"T\", \"TH\", \"S\" -> \"TTS\";\r\n            default -> {\r\n                if(day.isEmpty())\r\n                    break \"Please insert a valid day.\";\r\n                else\r\n                    break \"Looks like a Sunday.\";\r\n            }\r\n\r\n        };\r\n\r\n        System.out.println(result);\r\n<\/code><\/pre>\n
      \u8ba9\u6211\u4eec\u8fd0\u884c\u5305\u542b\u65b0\u7684 JDK 12 Switch \u8868\u8fbe\u5f0f\u7684\u4ee5\u4e0b\u7a0b\u5e8f\u3002<\/p>\n
      public class SwitchExpressions {\r\n\r\n    public static void main(String[] args)\r\n    {\r\n        System.out.println(\"New Switch Expression result:\");\r\n        executeNewSwitchExpression(\"M\");\r\n        executeNewSwitchExpression(\"TH\");\r\n        executeNewSwitchExpression(\"\");\r\n        executeNewSwitchExpression(\"SUN\");\r\n    }\r\n\r\n    public static void executeNewSwitchExpression(String day){\r\n\r\n        String result = switch (day) {\r\n            case \"M\", \"W\", \"F\" -> \"MWF\";\r\n            case \"T\", \"TH\", \"S\" -> \"TTS\";\r\n            default -> {\r\n                if(day.isEmpty())\r\n                    break \"Please insert a valid day.\";\r\n                else\r\n                    break \"Looks like a Sunday.\";\r\n            }\r\n\r\n        };\r\n\r\n        System.out.println(result);\r\n    }\r\n}\r\n<\/code><\/pre>\n
      \u7531\u4e8e\u8fd9\u662f\u4e00\u4e2a\u9884\u89c8\u529f\u80fd\uff0c\u8bf7\u786e\u4fdd\u60a8\u9009\u62e9\u4e86Java 12\u9884\u89c8\u7248\u4f5c\u4e3a\u8bed\u8a00\u7ea7\u522b\u3002\u8981\u7f16\u8bd1\u4e0a\u8ff0\u4ee3\u7801\uff0c\u8bf7\u8fd0\u884c\u4ee5\u4e0b\u547d\u4ee4\u3002<\/p>\n
      javac -Xlint:preview --enable-preview -source 12 src\/main\/java\/SwitchExpressions.java\r\n<\/code><\/pre>\n
      \u5728\u8fd0\u884c\u7f16\u8bd1\u7a0b\u5e8f\u4e4b\u540e\uff0c\u5728\u63a7\u5236\u53f0\u4e0a\u6211\u4eec\u5f97\u5230\u4e86\u4ee5\u4e0b\u7ed3\u679c\u3002<\/p>\n
      \n    \"Java\n<\/div>\n
      switch\u8868\u8fbe\u5f0f\u662f\u4e00\u79cd\u9884\u89c8\u8bed\u8a00\u529f\u80fd\u3002\u8fd9\u610f\u5473\u7740\u5c3d\u7ba1\u5b83\u5df2\u7ecf\u5b8c\u6574\uff0c\u4f46\u5728\u672a\u6765\u7684Java\u7248\u672c\u4e2d\u53ef\u80fd\u4e0d\u4f1a\u88ab\u786e\u8ba4\u3002<\/p>\n
      2. \u6587\u4ef6\u4e0d\u5339\u914d\u65b9\u6cd5<\/h3>\n
      Java 12\u65b0\u589e\u4e86\u4e00\u79cd\u6bd4\u8f83\u4e24\u4e2a\u6587\u4ef6\u7684\u65b9\u6cd5\u3002<\/p>\n
      public static long mismatch(Path path, Path path2) throws IOException\r\n<\/code><\/pre>\n
      \u5982\u679c\u4e24\u4e2a\u6587\u4ef6\u5b58\u5728\u4e0d\u5339\u914d\u60c5\u51b5\uff0c\u5219\u8be5\u65b9\u6cd5\u8fd4\u56de\u7b2c\u4e00\u4e2a\u4e0d\u5339\u914d\u7684\u4f4d\u7f6e\uff0c\u5982\u679c\u6ca1\u6709\u4e0d\u5339\u914d\u5219\u8fd4\u56de-1L\u3002<\/p>\n
        \n
      • \u5982\u679c\u5b57\u8282\u4e0d\u76f8\u540c\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u8fd4\u56de\u7b2c\u4e00\u4e2a\u4e0d\u5339\u914d\u5b57\u8282\u7684\u4f4d\u7f6e\u3002<\/li>\n
      • \u6587\u4ef6\u5927\u5c0f\u4e0d\u76f8\u540c\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u8fd4\u56de\u8f83\u5c0f\u6587\u4ef6\u7684\u5927\u5c0f\u3002<\/li>\n<\/ul>\n
        \u4ee5\u4e0b\u662f\u6765\u81eaIntelliJ Idea\u7684\u793a\u4f8b\u4ee3\u7801\u7247\u6bb5\uff1a<\/p>\n
        import java.io.IOException;\r\nimport java.nio.file.Files;\r\nimport java.nio.file.Path;\r\n\r\npublic class FileMismatchExample {\r\n\r\n    public static void main(String[] args) throws IOException {\r\n        Path filePath1 = Files.createTempFile(\"file1\", \".txt\");\r\n        Path filePath2 = Files.createTempFile(\"file2\", \".txt\");\r\n        Files.writeString(filePath1,\"JournalDev Test String\");\r\n        Files.writeString(filePath2,\"JournalDev Test String\");\r\n\r\n        long mismatch = Files.mismatch(filePath1, filePath2);\r\n\r\n        System.out.println(\"\u6587\u4ef6\u4e0d\u5339\u914d\u4f4d\u7f6e...\u5982\u679c\u6ca1\u6709\u4e0d\u5339\u914d\u5219\u8fd4\u56de-1\");\r\n\r\n        System.out.println(\"file1\u548cfile2\u4e2d\u7684\u4e0d\u5339\u914d\u4f4d\u7f6e\u662f >>>>\");\r\n        System.out.println(mismatch);\r\n\r\n        filePath1.toFile().deleteOnExit();\r\n        filePath2.toFile().deleteOnExit();\r\n\r\n        System.out.println();\r\n\r\n        Path filePath3 = Files.createTempFile(\"file3\", \".txt\");\r\n        Path filePath4 = Files.createTempFile(\"file4\", \".txt\");\r\n        Files.writeString(filePath3,\"JournalDev Test String\");\r\n        Files.writeString(filePath4,\"JournalDev.com Test String\");\r\n\r\n        long mismatch2 = Files.mismatch(filePath3, filePath4);\r\n\r\n        System.out.println(\"file3\u548cfile4\u4e2d\u7684\u4e0d\u5339\u914d\u4f4d\u7f6e\u662f >>>>\");\r\n        System.out.println(mismatch2);\r\n\r\n        filePath3.toFile().deleteOnExit();\r\n        filePath4.toFile().deleteOnExit();\r\n\r\n\r\n\r\n    }\r\n\r\n}\r\n<\/code><\/pre>\n
        \u5f53\u4e0a\u8ff0Java\u7a0b\u5e8f\u88ab\u7f16\u8bd1\u5e76\u8fd0\u884c\u65f6\u7684\u8f93\u51fa\u662f\uff1a<\/p>\n
        \n    \"Java\u6587\u4ef6\u4e0d\u5339\u914d\u793a\u4f8b\u7a0b\u5e8f\u8f93\u51fa\"\n<\/div>\n
        3. \u7d27\u51d1\u6570\u5b57\u683c\u5f0f\u5316<\/h3>\n
        import java.text.NumberFormat;\r\nimport java.util.Locale;\r\n\r\npublic class CompactNumberFormatting {\r\n\r\n\r\n    public static void main(String[] args)\r\n    {\r\n        System.out.println(\"\u7d27\u51d1\u683c\u5f0f\u5316\u662f:\");\r\n        NumberFormat upvotes = NumberFormat\r\n                .getCompactNumberInstance(new Locale(\"en\", \"US\"), NumberFormat.Style.SHORT);\r\n        upvotes.setMaximumFractionDigits(1);\r\n\r\n        System.out.println(upvotes.format(2592) + \" \u4e2a\u8d5e\");\r\n\r\n\r\n        NumberFormat upvotes2 = NumberFormat\r\n                .getCompactNumberInstance(new Locale(\"en\", \"US\"), NumberFormat.Style.LONG);\r\n        upvotes2.setMaximumFractionDigits(2);\r\n        System.out.println(upvotes2.format(2011) + \" \u4e2a\u8d5e\");\r\n    }\r\n\r\n\r\n}\r\n<\/code><\/pre>\n
        \n    \"Java\u7d27\u51d1\u6570\u5b57\u683c\u5f0f\u5316\u7a0b\u5e8f\u8f93\u51fa\"\n<\/div>\n
        4. \u5212\u5206\u6536\u96c6\u5668<\/h3>\n
        Teeing Collector\uff08\u5206\u6d41\u6536\u96c6\u5668\uff09\u662f\u5728 Streams API \u4e2d\u5f15\u5165\u7684\u65b0\u6536\u96c6\u5de5\u5177\u3002\u8fd9\u4e2a\u6536\u96c6\u5de5\u5177\u6709\u4e09\u4e2a\u53c2\u6570 – \u4e24\u4e2a\u6536\u96c6\u5668\u548c\u4e00\u4e2a\u53cc\u51fd\u6570\u3002\u6240\u6709\u7684\u8f93\u5165\u503c\u90fd\u4f1a\u4f20\u9012\u7ed9\u6bcf\u4e2a\u6536\u96c6\u5668\uff0c\u5e76\u4e14\u7ed3\u679c\u53ef\u5728\u53cc\u51fd\u6570\u4e2d\u83b7\u5f97\u3002<\/p>\n
        double mean = Stream.of(1, 2, 3, 4, 5)\r\n                .collect(Collectors.teeing(\r\n                        summingDouble(i -> i),\r\n                        counting(),\r\n                        (sum, n) -> sum \/ n));\r\n\r\nSystem.out.println(mean);\r\n<\/code><\/pre>\n
        \u8f93\u51fa\u662f3.0\u3002<\/p>\n
        5. Java\u5b57\u7b26\u4e32\u7684\u65b0\u65b9\u6cd5<\/h3>\n
        Java 12\u4e2d\u5f15\u5165\u4e864\u79cd\u65b0\u65b9\u6cd5\uff0c\u5b83\u4eec\u5206\u522b\u662f\uff1a<\/p>\n
          \n
        • indent(int n) – \u7f29\u8fdb\u65b9\u6cd5<\/li>\n
        • transform(Function f) – \u8f6c\u6362\u65b9\u6cd5<\/li>\n
        • Optional describeConstable() – \u63cf\u8ff0\u5e38\u91cf\u65b9\u6cd5<\/li>\n
        • String resolveConstantDesc\u200b(MethodHandles.Lookup lookup) – \u89e3\u6790\u5e38\u91cf\u63cf\u8ff0\u65b9\u6cd5<\/li>\n<\/ul>\n
          \u8981\u8be6\u7ec6\u4e86\u89e3\u4e0a\u8ff0\u65b9\u6cd5\u53ca\u5176\u5b9e\u73b0\uff0c\u8bf7\u53c2\u8003\u6211\u4eec\u7684Java 12\u5b57\u7b26\u4e32\u65b9\u6cd5\u6559\u7a0b\u3002<\/p>\n
          6. JEP 334: JVM Constants API – JEP 334\uff1aJVM \u5e38\u91cf API<\/h3>\n
          \u8fd9\u4e2a JEP \u5f15\u5165\u4e86\u4e00\u4e2a\u65b0\u5305 java.lang.constant\u3002\u5bf9\u4e8e\u4e0d\u4f7f\u7528\u5e38\u91cf\u6c60\u7684\u5f00\u53d1\u8005\u6765\u8bf4\uff0c\u8fd9\u5e76\u4e0d\u662f\u5f88\u6709\u7528\u3002<\/p>\n
          7. JEP 305: instanceof\u7684\u6a21\u5f0f\u5339\u914d\uff08\u9884\u89c8\uff09<\/h3>\n
          \u53e6\u4e00\u4e2a\u9884\u89c8\u8bed\u8a00\u529f\u80fd\uff01\u4ee5\u524d\u5c06\u4e00\u79cd\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u7c7b\u578b\u7684\u65b9\u6cd5\u662f\uff1a<\/p>\n
          if (obj instanceof String) {\r\n    String s = (String) obj;\r\n    \/\/ \u4ece\u8fd9\u91cc\u5f00\u59cb\u53ef\u4ee5\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528s\r\n}\r\n<\/code><\/pre>\n
          \u65b0\u7684\u65b9\u5f0f\u662f\uff1a<\/p>\n
          if (obj instanceof String s) {\r\n    \/\/ \u53ef\u4ee5\u5728\u8fd9\u91cc\u76f4\u63a5\u4f7f\u7528s\r\n} \r\n<\/code><\/pre>\n
          \u8fd9\u6837\u505a\u53ef\u4ee5\u907f\u514d\u4e00\u4e9b\u4e0d\u5fc5\u8981\u7684\u7c7b\u578b\u8f6c\u6362\u3002<\/p>\n
          JDK 12 \u4e2d\u5df2\u79fb\u9664\u539f\u59cb\u5b57\u7b26\u4e32\u5b57\u9762\u503c\u3002<\/p>\n
          \u8fd9\u7bc7\u6587\u7ae0\u4ecb\u7ecd\u4e86Java 12\u7684\u7279\u6027\uff0c\u5230\u8fd9\u91cc\u5c31\u7ed3\u675f\u4e86\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
          \u6700\u7ec8\uff0cJDK 12\u4f5c\u4e3a\u516d\u4e2a\u6708\u53d1\u5e03\u5468\u671f\u7684\u4e00\u90e8\u5206\u5df2\u7ecf\u53d1\u5e03\u4e86\u3002\u5b83\u662f\u7ee7\u4e0a\u4e00\u4e2aJava LTS\u7248\u672c11\u4e4b\u540e\u63a8\u51fa\u7684\u3002\u6211\u4eec\u4e4b […]<\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[2041,761,1244,180,2042],"class_list":["post-753","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-java-12","tag-java"],"yoast_head":"\nJava 12\u65b0\u7279\u6027\u5168\u9762\u89e3\u6790\uff1a\u5f00\u53d1\u8005\u5fc5\u77e5\u7684\u529f\u80fd\u6539\u8fdb\u4e0e\u5e94\u7528\u6280\u5de7 - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"\u6df1\u5165\u89e3\u6790Java 12\u7248\u672c\u5e26\u6765\u7684\u91cd\u8981\u65b0\u7279\u6027\u548c\u6539\u8fdb\uff0c\u5305\u62ecSwitch\u8868\u8fbe\u5f0f\u3001\u65b0\u7684String\u65b9\u6cd5\u3001GC\u6539\u8fdb\u7b49\u6838\u5fc3\u529f\u80fd\u3002\u672c\u6587\u4e3aJava\u5f00\u53d1\u8005\u63d0\u4f9b\u5168\u9762\u7684\u6280\u672f\u5206\u6790\u3001\u4ee3\u7801\u793a\u4f8b\u548c\u5b9e\u6218\u5e94\u7528\u6280\u5de7\uff0c\u52a9\u60a8\u5feb\u901f\u638c\u63e1Java 12\u7684\u6700\u65b0\u529f\u80fd\uff0c\u63d0\u5347\u5f00\u53d1\u6548\u7387\u3002\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/zh\/blog\/java-12-\u7279\u6027\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Java 12\u65b0\u7279\u6027\u5168\u9762\u89e3\u6790\uff1a\u5f00\u53d1\u8005\u5fc5\u77e5\u7684\u529f\u80fd\u6539\u8fdb\u4e0e\u5e94\u7528\u6280\u5de7\" \/>\n<meta property=\"og:description\" content=\"\u6df1\u5165\u89e3\u6790Java 12\u7248\u672c\u5e26\u6765\u7684\u91cd\u8981\u65b0\u7279\u6027\u548c\u6539\u8fdb\uff0c\u5305\u62ecSwitch\u8868\u8fbe\u5f0f\u3001\u65b0\u7684String\u65b9\u6cd5\u3001GC\u6539\u8fdb\u7b49\u6838\u5fc3\u529f\u80fd\u3002\u672c\u6587\u4e3aJava\u5f00\u53d1\u8005\u63d0\u4f9b\u5168\u9762\u7684\u6280\u672f\u5206\u6790\u3001\u4ee3\u7801\u793a\u4f8b\u548c\u5b9e\u6218\u5e94\u7528\u6280\u5de7\uff0c\u52a9\u60a8\u5feb\u901f\u638c\u63e1Java 12\u7684\u6700\u65b0\u529f\u80fd\uff0c\u63d0\u5347\u5f00\u53d1\u6548\u7387\u3002\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/java-12-\u7279\u6027\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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