{"id":5532,"date":"2026-01-23T17:26:43","date_gmt":"2026-01-23T09:26:43","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=5532"},"modified":"2026-01-23T17:26:43","modified_gmt":"2026-01-23T09:26:43","slug":"1-%e8%a1%8c%e4%bb%a3%e7%a0%81%ef%bc%8c%e4%b8%89%e4%b8%aa-null%ef%bc%8cjava-%e6%8b%92%e7%bb%9d%e4%ba%86-elvis-%e6%93%8d%e4%bd%9c%e7%ac%a6","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=5532","title":{"rendered":"1 \u884c\u4ee3\u7801\uff0c\u4e09\u4e2a null\uff0cJava \u62d2\u7edd\u4e86 Elvis \u64cd\u4f5c\u7b26"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">NPE \u8ba9\u6211\u4eec\u6df1\u591c\u52a0\u73ed\uff0cJEP 358 \u6551\u6211\u4eec\u7684\u547d\uff0c\u4f46\u201c?.\u201d\u64cd\u4f5c\u7b26\u5374\u88ab Oracle\uff0c\u4e5f\u5c31\u662f Java \u201c\u62d2\u4e4b\u95e8\u5916\u201d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6bcf\u4e2a Java \u7a0b\u5e8f\u5458\u90fd\u66fe\u88ab<code>#NullPointerException<\/code>\uff08NPE\uff09\u652f\u914d\u8fc7\uff0c\u5c24\u5176\u662f\u521d\u5165\u884c\u7684\u65f6\u5019\u30021 \u884c\u770b\u4f3c\u7b80\u5355\u7684<code>user.getGroup().getLeader().getDeptName()<\/code>\u4ee3\u7801\uff0c\u4e00\u65e6\u629b\u51fa NPE\uff0c\u4e0d\u5c11\u4eba\u66fe\u7ecf\u5bf9\u7740\u5806\u6808\u4fe1\u606f\u6293\u8033\u6320\u816e\uff0c\u731c\u6d4b\u5230\u5e95\u662f user\u3001group \u8fd8\u662f leader \u4e3a null\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u597d\u5728\u4ece Java 14 \u5f15\u5165\u7684 JEP 358 \u7279\u6027\u4e4b\u540e\uff0c\u7ec8\u7ed3\u4e86\u8fd9\u573a\u201c\u731c\u8c1c\u6e38\u620f\u201d\uff0c\u4f46\u662f\u8fd9\u5e76\u6ca1\u6709\u89e3\u51b3 null \u5e26\u6765\u7684 NPE \u95ee\u9898\u3002Java \u53cd\u800c\u5f15\u5165\u4e86\u4e00\u4e2a\u9887\u5177\u4e89\u8bae\u7684 Optional\uff0c\u8bd5\u56fe\u8ba9 NPE \u95ee\u9898\u5f97\u5230\u66f4\u7a33\u59a5\u7684\u5904\u7406\uff0c\u4f46\u662f\u8fd9\u4e2a Optional \u5728\u793e\u533a\u91cc\u7684\u201c\u540d\u58f0\u201d\u975e\u5e38\u4e0d\u597d\uff0c\u88ab\u591a\u6570\u4eba\u79f0\u4e3a\u9e21\u808b\u3002\u5177\u4f53\u53ef\u4ee5\u53c2\u8003\u6211\u7684\u8fd9\u4e9b\u6587\u7ae0\u300a<a href=\"https:\/\/mp.weixin.qq.com\/s\/gdvGqd0NSae9Y1vne99uVQ\">https:\/\/mp.weixin.qq.com\/s\/gdvGqd0NSae9Y1vne99uVQ<\/a>\u300b\u3001\u300a<a href=\"https:\/\/mp.weixin.qq.com\/s\/Ard-MCSFITVcvyL71XQchQ\">https:\/\/mp.weixin.qq.com\/s\/Ard-MCSFITVcvyL71XQchQ<\/a>\u300b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u9762\u5bf9\u8fd9\u79cd\uff0c1 \u884c\u4ee3\u7801\uff0c\u4e09\u4e2a null\uff0cKotlin \u6709 \u201c?.\u201d\uff0cJava \u4e3a\u4ec0\u4e48\u6ca1\u6709<code>?.<\/code>\uff0c\u8fd9\u4e2a\u5b89\u5168\u5bfc\u822a\u64cd\u4f5c\u7b26\u81f3\u4eca\u4ecd\u672a\u52a0\u5165 Java \u5927\u5bb6\u5ead\u7684\u539f\u56e0\u662f\u4ec0\u4e48\uff1f\u4eca\u5929\u6211\u4eec\u5c31\u4e00\u8d77\u6765\u804a\u4e00\u804a\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">JEP 358<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java 14 \u53d1\u5e03\u7684\u65f6\u5019\uff0c\u6211\u770b\u5230\u4e86 JEP 358\uff0c\u6211\u672c\u4ee5\u4e3a\u770b\u5230\u4e86\u5e0c\u671b\uff0c\u8fd9\u4e9b\u5e74\u624d\u77e5\u9053\uff0c\u6211\u770b\u5230\u7684\u662f\u5931\u671b&#x1f923;\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u63d0\u6848\u8981\u89e3\u51b3\u7684\u95ee\u9898\u662f\uff0c\u8be6\u7ec6\u7cbe\u786e\u7684\u6307\u51fa\u662f\u5177\u4f53\u662f\u54ea\u4e2a\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\u4e3a null\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728\u8fd9\u4e2a\u63d0\u6848\u4e4b\u524d\uff0c\u6bd4\u5982\u7c7b\u4f3c\u4e0b\u9762\u8fd9\u4e2a\u5f02\u5e38\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Exception in thread \"main\" java.lang.NullPointerException\n    at com.xttblog.NpeTest.main(NpeTest.java:5)<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6211\u4eec\u5bf9\u8fd9\u4e2a\u7a7a\u5f02\u5e38\u7834\u6848\u65f6\uff0c\u5c31\u50cf\u4fa6\u63a2\u7834\u6848\u53ea\u7ed9\u4e86\u4f60\u4e00\u4e2a\u6848\u53d1\u5730\u70b9\uff08\u7b2c 5 \u884c\uff09\uff0c\u5374\u6ca1\u6709\u4efb\u4f55\u5173\u4e8e\u51f6\u624b\uff08\u54ea\u4e2a\u53d8\u91cf\u4e3a null\uff09\u7684\u7ebf\u7d22\u3002\u5bf9\u4e8e<code>a.b.c.i = 99;<\/code>\u8fd9\u6837\u7684\u94fe\u5f0f\u8c03\u7528\uff0c\u6839\u672c\u65e0\u6cd5\u4ece\u5806\u6808\u4e2d\u5224\u65ad\u662f a\u3001b \u8fd8\u662f c \u4e3a null\u3002\u901a\u5e38\uff0c\u6211\u4eec\u53ea\u80fd\u901a\u8fc7\u6dfb\u52a0\u65e5\u5fd7\u3001\u65ad\u70b9\u8c03\u8bd5\uff0c\u751a\u81f3\u91cd\u6784\u4ee3\u7801\u6765\u62c6\u5206\u8c03\u7528\u94fe\uff0c\u624d\u80fd\u5b9a\u4f4d\u95ee\u9898\u3002\u8fd9\u5bf9\u4e8e\u7ebf\u4e0a\u6545\u969c\u6392\u67e5\u6765\u8bf4\uff0c\u6548\u7387\u6781\u4f4e\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e8e\u662f\uff0cJava \u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u957f\u671f\u75db\u70b9\uff0cOpenJDK \u5728 Java 14 \u4e2d\u6b63\u5f0f\u5f15\u5165\u4e86<code>#JEP 358: Helpful NullPointerExceptions #\u4e1a\u4f59\u8349<\/code>\uff08\u53cb\u597d\u7684\u7a7a\u6307\u9488\u5f02\u5e38\uff09\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u9879\u7279\u6027\u8ba9 JVM \u5728\u629b\u51fa NPE \u65f6\uff0c\u4e0d\u518d\u53ea\u662f\u51b7\u51b0\u51b0\u5730\u544a\u8bc9\u4f60\u201c\u51fa\u4e8b\u4e86\u201d\uff0c\u800c\u662f\u4f1a\u63d0\u4f9b\u4e00\u4efd\u8be6\u7ec6\u7684\u201c\u76ee\u51fb\u8005\u8bc1\u8bcd\u201d\uff0c\u7cbe\u786e\u6307\u51fa\u662f\u54ea\u4e2a\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\u4e3a null\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u4ee3\u7801: a.b.c.i = 99;\nException in thread \"main\" java.lang.NullPointerException:\nCannot read field \"c\" because \"a.b\" is null\n    at NpeTest.main(NpeTest.java:5)<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">Kotlin \u7684 \u201c?.\u201d<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u7528\u8fc7 Kotlin\uff0c\u6216\u89c1\u8fc7 Kotlin \u7684\u5e94\u8be5\u77e5\u9053\uff0c\u5b83\u6709\u4e00\u4e2a<code>?.<\/code>\u5f0f\u7684\u8bed\u6cd5\u3002\u652f\u6301\u4e0b\u9762\u8fd9\u6837\u7684\u94fe\u5f0f\u8c03\u7528\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5373\u4f7f return null \u8fd4\u56de\u7a7a\uff0c\u4e5f\u4e0d\u4f1a\u629b\u51fa NPE\n\nString text = user.getGroup()?.getLeader()?.getDeptName();\n\nval deptName = user?.group?.leader?.deptName<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u5c31\u662f Elvis \u8868\u8fbe\u5f0f (Null Coalescing)\u7ed9\u5b83\u7684\u4e00\u4e2a\u515c\u5e95\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7c7b\u4f3c<code>?.<\/code>\u8fd9\u6837\u7684\u5b89\u5168\u5bfc\u822a\u64cd\u4f5c\u7b26\uff08Safe Navigation Operator\uff09\u5728 Groovy\u3001Kotlin\u3001JavaScript\u3001C#\u3001Swift\u3001Ruby \u4e2d\u90fd\u5f97\u5230\u4e86\u7c7b\u4f3c\u7684\u652f\u6301\uff0c\u7136\u800c Java \u5374\u5f88\u5934\u94c1\uff0c\u5b83\u4e0d\u652f\u6301\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e8b\u5b9e\u4e0a\uff0c\u5728 Java 7 \u7684\u65e9\u671f\u8ba8\u8bba\u4e2d\uff0c\u5c31\u66fe\u6709\u4eba\u63d0\u8bae\u52a0\u5165\u7c7b\u4f3c\u201cElvis \u64cd\u4f5c\u7b26\u201d\u7684\u8bed\u6cd5\u7cd6\uff0c\u4f46\u6700\u7ec8\u88ab\u62d2\u7edd\u4e86\u3002\u5177\u4f53\u7684\u7ec6\u8282\u53c2\u8003\u8fd9\u7bc7\u6587\u7ae0<code>https:\/\/mail.openjdk.org\/pipermail\/coin-dev\/2009-March\/000047.html<\/code>\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Java \u62d2\u7edd\u7684\u539f\u56e0<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u793e\u533a\u91cc\u603b\u7ed3\u4e86\u4e0d\u5c11 Java \u62d2\u7edd\u7684\u539f\u56e0\uff0c\u4f46\u6211\u8ba4\u4e3a\u8fd9\u5f88\u53ef\u80fd\u90fd\u662f\u8868\u9762\u539f\u56e0\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u66f4\u6df1\u5c42\u6b21\u7684\u539f\u56e0\u662f\uff0cjava 7 \u90a3\u4e2a\u65f6\u5019\uff0c\u9762\u4e34\u7740\u88ab\u6536\u8d2d\uff0c\u4ee5\u53ca\u4f17\u591a\u7279\u6027\u96be\u4ea7\u7684\u539f\u56e0\uff0c\u6ca1\u6709\u4f59\u529b\u6765\u5b9e\u73b0\u4e00\u4e2a\u6781\u5176\u590d\u6742\u7684\u64cd\u4f5c\u7b26\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8981\u77e5\u9053\uff0c\u90a3\u4e2a\u65f6\u5019\uff0cJava 7 \u5ef6\u671f\u3001\u5ef6\u671f\uff0c\u8fd8\u662f\u5ef6\u671f\uff0c\u5305\u62ec lambda \u5728\u5185\u7684\u4f17\u591a\u7279\u6027\u90fd\u780d\u6389\uff0c\u653e\u5230 Java 8 \u4e86\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6240\u4ee5\uff0c\u90a3\u4e2a\u65f6\u5019\uff0cJava \u56e2\u961f\u7ed9\u51fa\u7684\u539f\u56e0\uff0c\u6211\u4e00\u70b9\u4e5f\u4e0d\u89c9\u5f97\u662f\u963b\u788d\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u8bed\u8a00\u54f2\u5b66\uff1aJava \u7684\u8bbe\u8ba1\u54f2\u5b66\u503e\u5411\u4e8e\u663e\u5f0f\u548c\u660e\u786e\u3002\u6838\u5fc3\u5f00\u53d1\u56e2\u961f\u8ba4\u4e3a\uff0c\u4f7f\u7528 Optional \u7c7b\u6216\u4f20\u7edf\u7684 if \u5224\u65ad\u867d\u7136\u4ee3\u7801\u7565\u663e\u5197\u957f\uff0c\u4f46\u903b\u8f91\u66f4\u6e05\u6670\uff0c\u610f\u56fe\u66f4\u660e\u786e\u3002<\/li><li>\u5df2\u6709\u66ff\u4ee3\u65b9\u6848\uff1aJava 8 \u5f15\u5165\u7684 Optional \u7c7b\u5c31\u662f\u5b98\u65b9\u63a8\u8350\u7684\u5904\u7406\u53ef\u80fd\u4e3a null \u7684\u503c\u7684\u65b9\u5f0f\u3002\u867d\u7136\u5b83\u5728\u5904\u7406\u6df1\u5c42\u5d4c\u5957\u65f6\u4f9d\u7136\u4e0d\u591f\u4f18\u96c5\uff0c\u4f46\u5b83\u63d0\u4f9b\u4e86\u4e00\u79cd\u51fd\u6570\u5f0f\u7684\u3001\u94fe\u5f0f\u8c03\u7528\u7684\u89e3\u51b3\u65b9\u6848\u3002<\/li><li>\u517c\u5bb9\u6027\u4e0e\u8bed\u6cd5\u590d\u6742\u6027\uff1a\u5411\u4e00\u95e8\u6210\u719f\u4e14\u5e9e\u5927\u7684\u8bed\u8a00\u4e2d\u6dfb\u52a0\u65b0\u7684\u64cd\u4f5c\u7b26\uff0c\u9700\u8981\u8003\u8651\u5176\u4e0e\u73b0\u6709\u8bed\u6cd5\u3001\u6cdb\u578b\u3001\u7c7b\u578b\u63a8\u65ad\u7b49\u7279\u6027\u7684\u4ea4\u4e92\uff0c\u8bc4\u4f30\u5176\u5e26\u6765\u7684\u590d\u6742\u6027\u662f\u5426\u503c\u5f97\u3002<\/li><li>Java \u7684\u6838\u5fc3\u8bbe\u8ba1\u539f\u5219\u4e4b\u4e00\uff1a \u201c\u663e\u5f0f\u4f18\u4e8e\u9690\u5f0f\u201d\uff08Explicit is better than implicit\uff09\u3002<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u603b\u4e4b\uff0c\u8fd9\u7c7b<code>?.<\/code>\u5b89\u5168\u5bfc\u822a\u64cd\u4f5c\u7b26\u6216\u53ef\u9009\u94fe\u64cd\u4f5c\u7b26\uff0c\u5728 Java 7 \u65f6\u671f\u5c31\u88ab\u62d2\u7edd\u4e86\u3002\u90a3\u65f6\uff0c\u5c31\u6709\u793e\u533a\u63d0\u8bae\u5f15\u5165\u7c7b\u4f3c<code>?.<\/code>\u6216 <code>?:<\/code>\uff08Elvis \u64cd\u4f5c\u7b26\uff09\u7684\u8bed\u6cd5\u7cd6\uff0c\u4f46\u90fd\u88ab\u5f53\u65f6\u7684\u8bed\u8a00\u56e2\u961f\uff08\u7531 Gilad Bracha \u7b49\u4eba\u4e3b\u5bfc\uff09\u660e\u786e\u62d2\u7edd\uff0c\u7406\u7531\u4e4b\u4e00\u6b63\u662f\u201c\u7834\u574f\u8bed\u8a00\u4e00\u81f4\u6027\u201d\u548c\u201c\u9f13\u52b1\u4e0d\u826f\u5b9e\u8df5\u201d\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Java \u63a8\u8350\u65b9\u6848<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c31\u8fd9\u6837\uff0c\u4e00\u4e9b Java \u70ed\u7231\u8005\u7531\u7c89\u8f6c\u9ed1\u4e86\u3002\u800c\u5b98\u65b9\u63a8\u8350\u62e5\u62b1 Optional\uff0c\u539f\u56e0\u4e4b\u4e00\u5c31\u662f\u6211\u8bf4\u7684\uff0c\u5b83\u5b9e\u73b0\u8d77\u6765\u66f4\u7b80\u5355\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String deptName = Optional.ofNullable(user)\n    .map(User::getGroup)\n    .map(Group::getLeader)\n    .map(Leader::getDeptName)\n    .orElse(\"Unknown\");<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u66f4\u6709\u201c\u6076\u5fc3\u201d\u7684\u4eba\uff0c\u5c01\u88c5\u4e86\u4e00\u4e2a\u641e\u7b11\u7684\u5de5\u5177\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public static &lt;T&gt; T safeGet(Supplier&lt;T&gt; supplier, T defaultValue) {\n    try {\n        return supplier.get();\n    } catch (NullPointerException e) {\n        return defaultValue;\n    }\n}\n\n\/\/ \u4f7f\u7528\nString deptName = safeGet(() -&gt; user.getGroup().getLeader().getDeptName(), \"\u4e1a\u4f59\u8349\");<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5f53\u7136\uff0c\u4e5f\u6709\u4e00\u4e9b\u7b2c\u4e09\u65b9\u6846\u67b6\u6216\u4e09\u65b9\u5e93\uff0c\u5982 Vavr\uff08\u4ee5\u524d\u53eb Javaslang\uff09\uff0c\u63d0\u4f9b\u4e86\u66f4\u5f3a\u5927\u7684 Option \u7c7b\u578b\u548c\u6a21\u5f0f\u5339\u914d\uff0c\u80fd\u5199\u51fa\u66f4\u63a5\u8fd1\u51fd\u6570\u5f0f\u8bed\u8a00\u7684\u4ee3\u7801\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u603b\u7ed3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u6211\u4e2a\u4eba\u89c9\u5f97\u7c7b\u4f3c<code>?.<\/code>\u8fd9\u7c7b\u5b89\u5168\u5bfc\u822a\u64cd\u4f5c\u7b26\uff08Safe Navigation Operator\uff09\uff0c\u4e5f\u6709\u4eba\u79f0\u4e3a \u201c\u7a7a\u611f\u77e5\u64cd\u4f5c\u7b26\u201d \u6216 \u201c\u53ef\u9009\u94fe\u64cd\u4f5c\u7b26\uff08Optional Chaining Operator\uff09\u201d\uff0c\u6ca1\u6709\u88ab\u6b63\u5f0f\u63a8\u51fa\uff0c\u662f\u6709\u4e00\u90e8\u5206\u5386\u53f2\u539f\u56e0\u7684\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u800c\u73b0\u5728\u7684 Java \u8bed\u8a00\u67b6\u6784\u5e08\uff08\u5982 Brian Goetz\uff09\u4e5f\u591a\u6b21\u5728\u516c\u5f00\u573a\u5408\u8868\u793a\uff0c\u4ed6\u4eec\u66f4\u5173\u6ce8\u6a21\u5f0f\u5339\u914d\u3001\u503c\u7c7b\u578b\u3001\u6cdb\u578b\u589e\u5f3a\u7b49\u201c\u7ed3\u6784\u6027\u6539\u8fdb\u201d\uff0c\u800c\u975e\u589e\u52a0\u201c\u8bed\u6cd5\u7cd6\u201d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u793e\u533a\u91cc\uff0c\u867d\u7136\u4e5f\u6709\u4e00\u5c0f\u90e8\u5206\u547c\u58f0\uff0c\u4f46\u672a\u5f62\u6210\u8db3\u591f\u63a8\u52a8\u529b\u3002\u76f8\u53cd\uff0c\u5927\u5bb6\u8ba4\u4e3a\u5728\u4e91\u539f\u751f\u65f6\u4ee3\uff0c Project Loom\uff08\u865a\u62df\u7ebf\u7a0b\uff09\u3001Project Valhalla\uff08\u503c\u7c7b\u578b\uff09\u7b49\u91cd\u5927\u7279\u6027\u7684\u4f18\u5148\u7ea7\u66f4\u9ad8\uff0c<code>?.<\/code>\u7684\u4f18\u5148\u7ea7\u88ab\u9057\u5fd8\u5230\u4e86\u89d2\u843d\u3002\u66f4\u4f55\u51b5\u73b0\u5728\u6709\u4e86 Option\uff0c<code>?.<\/code>\u8fd9\u7c7b\u7279\u6027\u6216\u8bb8\u96be\u6709\u201c\u51fa\u5934\u4e4b\u65e5\u201d\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u53c2\u8003\u8d44\u6599<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li><code>https:\/\/mail.openjdk.org\/pipermail\/coin-dev\/2009-March\/000047.html<\/code><\/li><li><code>https:\/\/openjdk.org\/jeps\/358<\/code><\/li><li><code>https:\/\/en.wikipedia.org\/wiki\/Safe_navigation_operator<\/code><\/li><li><code>https:\/\/stackoverflow.com\/questions\/61042145\/java-14-nullpointerexception-no-detailed-message<\/code><\/li><li><code>https:\/\/vavr.io<\/code><\/li><li><code>https:\/\/www.baeldung.com\/java-8-elvis-operator-implementation<\/code><\/li><\/ul>\n<!-- <audio autoplay=\"autoplay\" height=\"100\" width=\"100\" hidden=\"true\"><source src=\"https:\/\/c.coka.la\/orAvPR.mp3\" type=\"audio\/mp3\"\/><\/audio><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/ws3.sinaimg.cn\/large\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/> --><p><!-- <img decoding=\"async\" src=\"https:\/\/raw.githubusercontent.com\/xmt1139057136\/xttblog\/master\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/>--><img decoding=\"async\" src=\"https:\/\/saas.51autoparts.cn\/api\/admin\/sys-file\/oss\/file?fileName=84db51f8561e448f9a4fda2eff0811f9.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/><\/p><p>\u6700\u540e\uff0c\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u4e2a\u4eba\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u4e1a\u4f59\u8349\uff08yyucao\uff09\uff01<b>\u53ef\u52a0\u4f5c\u8005\u5fae\u4fe1\u53f7\uff1a<font color=\"red\">xttblog2<\/font>\u3002\u5907\u6ce8\uff1a\u201c1\u201d\uff0c\u6dfb\u52a0\u535a\u4e3b\u5fae\u4fe1\u62c9\u4f60\u8fdb\u5fae\u4fe1\u7fa4\u3002\u5907\u6ce8\u9519\u8bef\u4e0d\u4f1a\u540c\u610f\u597d\u53cb\u7533\u8bf7\u3002<\/b>\u518d\u6b21\u611f\u8c22\u60a8\u7684\u5173\u6ce8\uff01\u540e\u7eed\u6709\u7cbe\u5f69\u5185\u5bb9\u4f1a\u7b2c\u4e00\u65f6\u95f4\u53d1\u7ed9\u60a8\uff01\u539f\u521b\u6587\u7ae0\u6295\u7a3f\u8bf7\u53d1\u9001\u81f3532009913@qq.com\u90ae\u7bb1\u3002\u5546\u52a1\u5408\u4f5c\u4e5f\u53ef\u6dfb\u52a0\u4f5c\u8005\u5fae\u4fe1\u8fdb\u884c\u8054\u7cfb\uff01<\/p><p>\u672c\u6587\u539f\u6587\u51fa\u5904\uff1a<a href=\"https:\/\/www.xttblog.com\">\u4e1a\u4f59\u8349<\/a>\uff1a &raquo; <a href=\"https:\/\/www.xttblog.com\/?p=5532\">1 \u884c\u4ee3\u7801\uff0c\u4e09\u4e2a null\uff0cJava \u62d2\u7edd\u4e86 Elvis \u64cd\u4f5c\u7b26<\/a><\/p><!-- <div class=\"bd-reward-stl\"><button id=\"bdRewardBtn\"><span><\/span><\/button><\/div> -->","protected":false},"excerpt":{"rendered":"<p>NPE \u8ba9\u6211\u4eec\u6df1\u591c\u52a0\u73ed\uff0cJEP 358 \u6551\u6211\u4eec\u7684\u547d\uff0c\u4f46\u201c?.\u201d\u64cd\u4f5c\u7b26\u5374\u88ab Oracle\uff0c\u4e5f\u5c31\u662f Java \u201c\u62d2 [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[267,866,1471,654,792],"class_list":["post-5532","post","type-post","status-publish","format-standard","hentry","category-java","tag-nullpointerexception","tag-optimizer","tag-optional","tag-wp_options","tag-792"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5532","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5532"}],"version-history":[{"count":1,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5532\/revisions"}],"predecessor-version":[{"id":5533,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5532\/revisions\/5533"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5532"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5532"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5532"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}