{"id":65457,"date":"2025-05-03T10:30:35","date_gmt":"2025-05-03T02:30:35","guid":{"rendered":"https:\/\/fwq.ai\/blog\/65457\/"},"modified":"2025-05-03T10:30:35","modified_gmt":"2025-05-03T02:30:35","slug":"java%e6%95%b0%e7%bb%84%e6%80%8e%e4%b9%88%e8%8e%b7%e5%8f%96%e7%a9%ba%e5%85%83%e7%b4%a0","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/65457\/","title":{"rendered":"java\u6570\u7ec4\u600e\u4e48\u83b7\u53d6\u7a7a\u5143\u7d20"},"content":{"rendered":"<blockquote><p>\n  java \u6570\u7ec4\u6ca1\u6709\u300c\u7a7a\u5143\u7d20\u300d\uff0c\u4f46\u53ef\u4ee5\u83b7\u53d6\u4e3a null \u7684\u5143\u7d20\u3002\u83b7\u53d6 null \u5143\u7d20\u7684\u7d22\u5f15\u53ef\u4ee5\u4f7f\u7528 for \u5faa\u73af\u6216 list \u8f6c\u6362\u540e\u83b7\u53d6\u7b2c\u4e00\u4e2a\u548c\u6700\u540e\u4e00\u4e2a null \u5143\u7d20\u7684\u7d22\u5f15\u3002\n<\/p><\/blockquote>\n<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/202411\/13\/2024111301250114790.jpg\" class=\"aligncenter\" title=\"java\u6570\u7ec4\u600e\u4e48\u83b7\u53d6\u7a7a\u5143\u7d20\u63d2\u56fe\" alt=\"java\u6570\u7ec4\u600e\u4e48\u83b7\u53d6\u7a7a\u5143\u7d20\u63d2\u56fe\" \/><\/p>\n<p><strong>Java \u6570\u7ec4\u83b7\u53d6\u7a7a\u5143\u7d20<\/strong><\/p>\n<p>Java \u6570\u7ec4\u4e2d\u4e0d\u5b58\u5728\u300c\u7a7a\u5143\u7d20\u300d\u7684\u6982\u5ff5\u3002\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u90fd\u5177\u6709\u786e\u5b9a\u7684\u503c\uff0c\u5373\u4f7f\u8fd9\u4e2a\u503c\u662f Java \u4e2d\u7684\u9ed8\u8ba4\u503c null\u3002<\/p>\n<p><strong>\u786e\u5b9a\u6570\u7ec4\u5143\u7d20\u662f\u5426\u4e3a null<\/strong><\/p>\n<p>\u8981\u786e\u5b9a\u6570\u7ec4\u5143\u7d20\u662f\u5426\u4e3a null\uff0c\u53ef\u4ee5\u4f7f\u7528 == \u8fd0\u7b97\u7b26\u8fdb\u884c\u6bd4\u8f83\u3002\u4f8b\u5982\uff1a<\/p>\n<p><span>\u7acb\u5373\u5b66\u4e60<\/span>\u201c\u201d\uff1b<\/p>\n<pre>int[] myArray = {1, 2, 3, null};\nif (myArray[3] == null) {\n    \/\/ myArray[3] \u4e3a\u7a7a\n}<\/pre>\n<p> \u767b\u5f55\u540e\u590d\u5236 <\/p>\n<p><strong>\u83b7\u53d6\u6570\u7ec4\u7a7a\u5143\u7d20\u7684\u7d22\u5f15<\/strong><\/p>\n<p>Java \u4e2d\u6ca1\u6709\u76f4\u63a5\u83b7\u53d6\u6570\u7ec4\u7a7a\u5143\u7d20\u7d22\u5f15\u7684\u65b9\u6cd5\u3002\u4f46\u662f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u65b9\u6cd5\u627e\u5230\u7b2c\u4e00\u4e2a\u6216\u6700\u540e\u4e00\u4e2a null \u5143\u7d20\u7684\u7d22\u5f15\uff1a<\/p>\n<p><strong>1. \u4f7f\u7528 for \u5faa\u73af<\/strong><\/p>\n<pre>int[] myArray = {1, 2, 3, null, 5};\nint firstNullIndex = -1;\nint lastNullIndex = -1;\n\nfor (int i = 0; i &lt; myArray.length; i++) {\n    if (myArray[i] == null) {\n        if (firstNullIndex == -1) {\n            firstNullIndex = i;\n        }\n        lastNullIndex = i;\n    }\n}<\/pre>\n<p> \u767b\u5f55\u540e\u590d\u5236 <\/p>\n<p><strong>2. \u4f7f\u7528 List<\/strong><\/p>\n<pre>List&lt;Integer&gt; myList = Arrays.asList(1, 2, 3, null, 5);\nint firstNullIndex = myList.indexOf(null);  \/\/ 3\nint lastNullIndex = myList.lastIndexOf(null);  \/\/ 3<\/pre>\n<p> \u767b\u5f55\u540e\u590d\u5236 <\/p>\n<p>\u4ee5\u4e0a\u5c31\u662fjava\u6570\u7ec4\u600e\u4e48\u83b7\u53d6\u7a7a\u5143\u7d20\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8IDCBABY\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>java \u6570\u7ec4\u6ca1\u6709\u300c\u7a7a\u5143\u7d20\u300d\uff0c\u4f46\u53ef\u4ee5\u83b7\u53d6\u4e3a null \u7684\u5143\u7d20\u3002\u83b7\u53d6 null \u5143\u7d20\u7684\u7d22\u5f15\u53ef\u4ee5\u4f7f\u7528 for \u5faa\u73af\u6216 list \u8f6c\u6362\u540e\u83b7\u53d6\u7b2c\u4e00\u4e2a\u548c\u6700\u540e\u4e00\u4e2a null \u5143\u7d20\u7684\u7d22\u5f15\u3002 Java \u6570\u7ec4\u83b7\u53d6\u7a7a\u5143\u7d20 Java \u6570\u7ec4\u4e2d\u4e0d\u5b58\u5728\u300c\u7a7a\u5143\u7d20\u300d\u7684\u6982\u5ff5\u3002\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u90fd\u5177\u6709\u786e\u5b9a\u7684\u503c\uff0c\u5373\u4f7f\u8fd9\u4e2a\u503c\u662f Java \u4e2d\u7684\u9ed8\u8ba4\u503c null\u3002 \u786e\u5b9a\u6570\u7ec4\u5143\u7d20\u662f\u5426\u4e3a null \u8981\u786e\u5b9a\u6570\u7ec4\u5143\u7d20\u662f\u5426\u4e3a null\uff0c\u53ef\u4ee5\u4f7f\u7528 == \u8fd0\u7b97\u7b26\u8fdb\u884c\u6bd4\u8f83\u3002\u4f8b\u5982\uff1a \u7acb\u5373\u5b66\u4e60\u201c\u201d\uff1b int[] myArray = {1, 2, 3, null}; if (myArray[3] == null) { \/\/ myArray[3] \u4e3a\u7a7a } \u767b\u5f55\u540e\u590d\u5236 \u83b7\u53d6\u6570\u7ec4\u7a7a\u5143\u7d20\u7684\u7d22\u5f15 Java \u4e2d\u6ca1\u6709\u76f4\u63a5\u83b7\u53d6\u6570\u7ec4\u7a7a\u5143\u7d20\u7d22\u5f15\u7684\u65b9\u6cd5\u3002\u4f46\u662f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u65b9\u6cd5\u627e\u5230\u7b2c\u4e00\u4e2a\u6216\u6700\u540e\u4e00\u4e2a null \u5143\u7d20\u7684\u7d22\u5f15\uff1a 1. \u4f7f\u7528 for \u5faa\u73af int[] myArray = [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-65457","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/65457","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=65457"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/65457\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=65457"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=65457"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=65457"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}