{"id":49911,"date":"2023-08-21T19:46:15","date_gmt":"2023-08-21T11:46:15","guid":{"rendered":"https:\/\/docs.pingcode.com\/?p=49911"},"modified":"2023-08-21T19:46:18","modified_gmt":"2023-08-21T11:46:18","slug":"java%e5%88%a4%e6%96%adnulla%e5%92%8canull%e7%9a%84%e5%8c%ba%e5%88%ab%e6%98%af%e4%bb%80%e4%b9%88","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/49911.html","title":{"rendered":"java\u5224\u65adnull!=a\u548ca!=null\u7684\u533a\u522b\u662f\u4ec0\u4e48"},"content":{"rendered":"\n
\n

\u5728Java\u7f16\u7a0b\u4e2d\uff0cnull != a<\/code>\u548ca != null<\/code>\u4e24\u4e2a\u8868\u8fbe\u5f0f\u7528\u4e8e\u68c0\u67e5\u53d8\u91cfa<\/code>\u662f\u5426\u4e0d\u7b49\u4e8enull<\/code>\u3002\u8fd9\u4e24\u79cd\u8868\u8fbe\u5f0f\u5b9e\u9645\u4e0a\u6ca1\u6709\u529f\u80fd\u4e0a\u7684\u533a\u522b\uff0c\u90fd\u8fd4\u56de\u76f8\u540c\u7684\u7ed3\u679c\u3002\u533a\u522b\u5728\u4e8e\u7f16\u5199\u98ce\u683c<\/strong>\u548c\u53ef\u8bfb\u6027<\/strong>\u3002\u4f8b\u5982\uff0c\u4e00\u4e9b\u5f00\u53d1\u8005\u53ef\u80fd\u66f4\u503e\u5411\u4e8e\u4f7f\u7528null != a<\/code>\u7684\u5f62\u5f0f\u6765\u589e\u52a0\u4ee3\u7801\u7684\u4e00\u81f4\u6027\u548c\u53ef\u8bfb\u6027\u3002\u672c\u6587\u5c06\u8fdb\u4e00\u6b65\u63a2\u8ba8\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u7684\u4f7f\u7528\u60c5\u5883\u548c\u80cc\u540e\u7684\u903b\u8f91\u3002<\/p>\n<\/blockquote>\n\n\n

\n
\"\"<\/figure><\/div>\n\n\n

\u4e00\u3001\u529f\u80fd\u548c\u903b\u8f91\u5206\u6790<\/strong><\/h2>\n\n\n\n
    \n
  • \u529f\u80fd\u4e00\u81f4<\/strong>\uff1a\u65e0\u8bba\u662fnull != a<\/code>\u8fd8\u662fa != null<\/code>\uff0c\u5b83\u4eec\u90fd\u662f\u7528\u6765\u5224\u65ad\u53d8\u91cfa<\/code>\u662f\u5426\u4e0d\u7b49\u4e8enull<\/code>\u3002<\/li>\n\n\n\n
  • \u903b\u8f91\u76f8\u540c<\/strong>\uff1a\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u7684\u903b\u8f91\u5b8c\u5168\u76f8\u540c\uff0c\u6ca1\u6709\u6027\u80fd\u6216\u529f\u80fd\u4e0a\u7684\u533a\u522b\u3002<\/li>\n<\/ul>\n\n\n\n

    \u4e8c\u3001\u7f16\u7a0b\u98ce\u683c\u8003\u8651<\/strong><\/h2>\n\n\n\n
      \n
    • \u53ef\u8bfb\u6027<\/strong>\uff1a\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u7684\u53ef\u8bfb\u6027\u5dee\u522b\u4e3b\u8981\u53d6\u51b3\u4e8e\u56e2\u961f\u6216\u4e2a\u4eba\u7684\u7f16\u7a0b\u4e60\u60ef\u3002\u6709\u4eba\u53ef\u80fd\u89c9\u5f97a != null<\/code>\u66f4\u81ea\u7136\uff0c\u6709\u4eba\u53ef\u80fd\u503e\u5411\u4e8enull != a<\/code>\u3002<\/li>\n\n\n\n
    • \u4e00\u81f4\u6027<\/strong>\uff1a\u6709\u4e9b\u5f00\u53d1\u8005\u559c\u6b22\u5c06\u5b57\u9762\u503c\u6216\u5e38\u91cf\u653e\u5728\u6bd4\u8f83\u64cd\u4f5c\u7684\u5de6\u4fa7\uff0c\u4ee5\u589e\u5f3a\u4ee3\u7801\u7684\u4e00\u81f4\u6027\uff0c\u5982null != a<\/code>\u3002<\/li>\n\n\n\n
    • \u9632\u6b62\u9519\u8bef<\/strong>\uff1a\u5728\u67d0\u4e9b\u8bed\u8a00\u4e2d\uff0c\u5c06\u5e38\u91cf\u653e\u5728\u5de6\u4fa7\u6709\u52a9\u4e8e\u9632\u6b62\u8bef\u7528\u8d4b\u503c\u64cd\u4f5c\u7b26=<\/code>\u4ee3\u66ff\u6bd4\u8f83\u64cd\u4f5c\u7b26!=<\/code>\u3002\u4f46\u5728Java\u4e2d\uff0c\u8fd9\u79cd\u8003\u8651\u5e76\u4e0d\u5fc5\u8981\uff0c\u56e0\u4e3aif (a = null)<\/code>\u4f1a\u5bfc\u81f4\u7f16\u8bd1\u9519\u8bef\u3002<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n

      \u5e38\u89c1\u95ee\u7b54<\/strong><\/h2>\n\n\n\n
        \n
      • 1.\u4e3a\u4ec0\u4e48\u6709\u4eba\u503e\u5411\u4e8e\u4f7f\u7528null != a\u7684\u5f62\u5f0f\uff1f<\/strong><\/li>\n\n\n\n
      • \u8fd9\u53ef\u80fd\u662f\u51fa\u4e8e\u4e2a\u4eba\u6216\u56e2\u961f\u7684\u7f16\u7a0b\u4e60\u60ef\uff0c\u6216\u8005\u4e3a\u4e86\u4e0e\u5176\u4ed6\u8bed\u8a00\u7684\u7f16\u7a0b\u4e60\u60ef\u4fdd\u6301\u4e00\u81f4\u3002<\/li>\n\n\n\n
      • 2.\u8fd9\u4e24\u79cd\u5f62\u5f0f\u5728\u6027\u80fd\u4e0a\u6709\u533a\u522b\u5417\uff1f<\/strong><\/li>\n\n\n\n
      • \u6ca1\u6709\u3002\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u5728\u7f16\u8bd1\u540e\u7684\u5b57\u8282\u7801\u662f\u76f8\u540c\u7684\uff0c\u6240\u4ee5\u6027\u80fd\u4e0a\u6ca1\u6709\u533a\u522b\u3002<\/li>\n\n\n\n
      • 3.\u8fd9\u4e24\u79cd\u5f62\u5f0f\u5728\u5176\u4ed6\u7f16\u7a0b\u8bed\u8a00\u4e2d\u662f\u5426\u901a\u7528\uff1f<\/strong><\/li>\n\n\n\n
      • \u8fd9\u4e24\u79cd\u5f62\u5f0f\u5728\u8bb8\u591a\u7c7bC\u7684\u7f16\u7a0b\u8bed\u8a00\u4e2d\u90fd\u662f\u901a\u7528\u7684\uff0c\u529f\u80fd\u548c\u903b\u8f91\u5b8c\u5168\u76f8\u540c\u3002<\/li>\n\n\n\n
      • 4.\u662f\u5426\u6709\u4f18\u5f02\u5b9e\u8df5\u63a8\u8350\u4f7f\u7528\u5176\u4e2d\u4e00\u79cd\u5f62\u5f0f\uff1f<\/strong><\/li>\n\n\n\n
      • \u6ca1\u6709\u7edf\u4e00\u7684\u4f18\u5f02\u5b9e\u8df5\u3002\u9009\u62e9\u54ea\u79cd\u5f62\u5f0f\u4e3b\u8981\u53d6\u51b3\u4e8e\u4e2a\u4eba\u6216\u56e2\u961f\u7684\u7f16\u7a0b\u98ce\u683c\u548c\u4e60\u60ef\u3002<\/li>\n\n\n\n
      • 5.\u5982\u679ca\u662f\u57fa\u672c\u7c7b\u578b\uff0c\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u8fd8\u6709\u610f\u4e49\u5417\uff1f<\/strong><\/li>\n\n\n\n
      • \u5982\u679ca<\/code>\u662f\u57fa\u672c\u7c7b\u578b\uff0c\u8fd9\u4e24\u4e2a\u8868\u8fbe\u5f0f\u662f\u6ca1\u6709\u610f\u4e49\u7684\uff0c\u56e0\u4e3a\u57fa\u672c\u7c7b\u578b\u7684\u53d8\u91cf\u4e0d\u80fd\u4e3anull<\/code>\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"\u5728Java\u7f16\u7a0b\u4e2d\uff0cnull != a\u548ca != null\u4e24\u4e2a\u8868\u8fbe\u5f0f\u7528\u4e8e\u68c0\u67e5\u53d8\u91cfa\u662f\u5426\u4e0d\u7b49\u4e8enull\u3002\u8fd9\u4e24\u79cd\u8868\u8fbe […]","protected":false},"author":6,"featured_media":49912,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[1679,1680,1681,1682,367],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/49911"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=49911"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/49911\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/49912"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=49911"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=49911"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=49911"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}