\u5bf9\u4e8e\u8fd9\u4e2a\u7cfb\u5217\u91cc\u7684\u95ee\u9898\uff0c\u6bcf\u4e2a\u5b66Java\u7684\u4eba\u90fd\u5e94\u8be5\u641e\u61c2\u3002\u5f53\u7136\uff0c\u5982\u679c\u53ea\u662f\u5b66Java\u73a9\u73a9\u5c31\u65e0\u6240\u8c13\u4e86\u3002\u5982\u679c\u4f60\u8ba4\u4e3a\u81ea\u5df1\u5df2\u7ecf\u8d85\u8d8a\u521d\u5b66\u8005\u4e86\uff0c\u5374\u4e0d\u5f88\u61c2\u8fd9\u4e9b\u95ee\u9898\uff0c\u8bf7\u5c06\u4f60\u81ea\u5df1\u91cd\u5f52\u521d\u5b66\u8005\u884c\u5217\u3002
\n
\n\u95ee\u9898\u4e00\uff1a\u6211\u58f0\u660e\u4e86\u4ec0\u4e48\uff01<\/p>\n
String s = “Hello world!”;<\/p>\n
\u8bb8\u591a\u4eba\u90fd\u505a\u8fc7\u8fd9\u6837\u7684\u4e8b\u60c5\uff0c\u4f46\u662f\uff0c\u6211\u4eec\u5230\u5e95\u58f0\u660e\u4e86\u4ec0\u4e48\uff1f\u56de\u7b54\u901a\u5e38\u662f\uff1a\u4e00\u4e2aString\uff0c\u5185\u5bb9\u662f\u201cHello world!\u201d\u3002\u8fd9\u6837\u6a21\u7cca\u7684\u56de\u7b54\u901a\u5e38\u662f\u6982\u5ff5\u4e0d\u6e05\u7684\u6839\u6e90\u3002\u5982\u679c\u8981\u51c6\u786e\u7684\u56de\u7b54\uff0c\u4e00\u534a\u7684\u4eba\u5927\u6982\u4f1a\u56de\u7b54\u9519\u8bef\u3002
\n\u8fd9\u4e2a\u8bed\u53e5\u58f0\u660e\u7684\u662f\u4e00\u4e2a\u6307\u5411\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u540d\u4e3a\u201cs\u201d\uff0c\u53ef\u4ee5\u6307\u5411\u7c7b\u578b\u4e3aString\u7684\u4efb\u4f55\u5bf9\u8c61\uff0c\u76ee\u524d\u6307\u5411”Hello world!”\u8fd9\u4e2aString\u7c7b\u578b\u7684\u5bf9\u8c61\u3002\u8fd9\u5c31\u662f\u771f\u6b63\u53d1\u751f\u7684\u4e8b\u60c5\u3002\u6211\u4eec\u5e76\u6ca1\u6709\u58f0\u660e\u4e00\u4e2aString\u5bf9\u8c61\uff0c\u6211\u4eec\u53ea\u662f\u58f0\u660e\u4e86\u4e00\u4e2a\u53ea\u80fd\u6307\u5411String\u5bf9\u8c61\u7684\u5f15\u7528\u53d8\u91cf\u3002\u6240\u4ee5\uff0c\u5982\u679c\u5728\u521a\u624d\u90a3\u53e5\u8bed\u53e5\u540e\u9762\uff0c\u5982\u679c\u518d\u8fd0\u884c\u4e00\u53e5\uff1a<\/p>\n
String string = s;<\/p>\n
\u6211\u4eec\u662f\u58f0\u660e\u4e86\u53e6\u5916\u4e00\u4e2a\u53ea\u80fd\u6307\u5411String\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u540d\u4e3astring\uff0c\u5e76\u6ca1\u6709\u7b2c\u4e8c\u4e2a\u5bf9\u8c61\u4ea7\u751f\uff0cstring\u8fd8\u662f\u6307\u5411\u539f\u6765\u90a3\u4e2a\u5bf9\u8c61\uff0c\u4e5f\u5c31\u662f\uff0c\u548cs\u6307\u5411\u540c\u4e00\u4e2a\u5bf9\u8c61\u3002<\/p>\n
\u95ee\u9898\u4e8c\uff1a”==”\u548cequals\u65b9\u6cd5\u7a76\u7adf\u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/p>\n
==\u64cd\u4f5c\u7b26\u4e13\u95e8\u7528\u6765\u6bd4\u8f83\u53d8\u91cf\u7684\u503c\u662f\u5426\u76f8\u7b49\u3002\u6bd4\u8f83\u597d\u7406\u89e3\u7684\u4e00\u70b9\u662f\uff1a
\nint a=10;
\nint b=10;
\n\u5219a==b\u5c06\u662ftrue\u3002
\n\u4f46\u4e0d\u597d\u7406\u89e3\u7684\u5730\u65b9\u662f\uff1a
\nString a=new String(“foo”);
\nString b=new String(“foo”);
\n\u5219a==b\u5c06\u8fd4\u56defalse\u3002<\/p>\n
\u6839\u636e\u524d\u4e00\u5e16\u8bf4\u8fc7\uff0c\u5bf9\u8c61\u53d8\u91cf\u5176\u5b9e\u662f\u4e00\u4e2a\u5f15\u7528\uff0c\u5b83\u4eec\u7684\u503c\u662f\u6307\u5411\u5bf9\u8c61\u6240\u5728\u7684\u5185\u5b58\u5730\u5740\uff0c\u800c\u4e0d\u662f\u5bf9\u8c61\u672c\u8eab\u3002a\u548cb\u90fd\u4f7f\u7528\u4e86new\u64cd\u4f5c\u7b26\uff0c\u610f\u5473\u7740\u5c06\u5728\u5185\u5b58\u4e2d\u4ea7\u751f\u4e24\u4e2a\u5185\u5bb9\u4e3a”foo”\u7684\u5b57\u7b26\u4e32\uff0c\u65e2\u7136\u662f\u201c\u4e24\u4e2a\u201d\uff0c\u5b83\u4eec\u81ea\u7136\u4f4d\u4e8e\u4e0d\u540c\u7684\u5185\u5b58\u5730\u5740\u3002a\u548cb\u7684\u503c\u5176\u5b9e\u662f\u4e24\u4e2a\u4e0d\u540c\u7684\u5185\u5b58\u5730\u5740\u7684\u503c\uff0c\u6240\u4ee5\u4f7f\u7528”==”\u64cd\u4f5c\u7b26\uff0c\u7ed3\u679c\u4f1a\u662ffalse\u3002\u8bda\u7136\uff0ca\u548cb\u6240\u6307\u7684\u5bf9\u8c61\uff0c\u5b83\u4eec\u7684\u5185\u5bb9\u90fd\u662f”foo”\uff0c\u5e94\u8be5\u662f\u201c\u76f8\u7b49\u201d\uff0c\u4f46\u662f==\u64cd\u4f5c\u7b26\u5e76\u4e0d\u6d89\u53ca\u5230\u5bf9\u8c61\u5185\u5bb9\u7684\u6bd4\u8f83\u3002
\n\u5bf9\u8c61\u5185\u5bb9\u7684\u6bd4\u8f83\uff0c\u6b63\u662fequals\u65b9\u6cd5\u505a\u7684\u4e8b\u3002<\/p>\n
\u770b\u4e00\u4e0bObject\u5bf9\u8c61\u7684equals\u65b9\u6cd5\u662f\u5982\u4f55\u5b9e\u73b0\u7684\uff1a
\n[java]boolean equals(Object o){
\n return this==o;
\n}[\/java]
\nObject\u5bf9\u8c61\u9ed8\u8ba4\u4f7f\u7528\u4e86==\u64cd\u4f5c\u7b26\u3002\u6240\u4ee5\u5982\u679c\u4f60\u81ea\u521b\u7684\u7c7b\u6ca1\u6709\u8986\u76d6equals\u65b9\u6cd5\uff0c\u90a3\u4f60\u7684\u7c7b\u4f7f\u7528equals\u548c\u4f7f\u7528==\u4f1a\u5f97\u5230\u540c\u6837\u7684\u7ed3\u679c\u3002\u540c\u6837\u4e5f\u53ef\u4ee5\u770b\u51fa\uff0cObject\u7684equals\u65b9\u6cd5\u6ca1\u6709\u8fbe\u5230equals\u65b9\u6cd5\u5e94\u8be5\u8fbe\u5230\u7684\u76ee\u6807\uff1a\u6bd4\u8f83\u4e24\u4e2a\u5bf9\u8c61\u5185\u5bb9\u662f\u5426\u76f8\u7b49\u3002\u56e0\u4e3a\u7b54\u6848\u5e94\u8be5\u7531\u7c7b\u7684\u521b\u5efa\u8005\u51b3\u5b9a\uff0c\u6240\u4ee5Object\u628a\u8fd9\u4e2a\u4efb\u52a1\u7559\u7ed9\u4e86\u7c7b\u7684\u521b\u5efa\u8005\u3002<\/p>\n
\u770b\u4e00\u4e0b\u4e00\u4e2a\u6781\u7aef\u7684\u7c7b\uff1a
\n[java]Class Monster{
\n private String content;
\n …
\n boolean equals(Object another){
\n return true;
\n }
\n}[\/java]
\n\u6211\u8986\u76d6\u4e86equals\u65b9\u6cd5\u3002\u8fd9\u4e2a\u5b9e\u73b0\u4f1a\u5bfc\u81f4\u65e0\u8bbaMonster\u5b9e\u4f8b\u5185\u5bb9\u5982\u4f55\uff0c\u5b83\u4eec\u4e4b\u95f4\u7684\u6bd4\u8f83\u6c38\u8fdc\u8fd4\u56detrue\u3002<\/p>\n
\u6240\u4ee5\u5f53\u4f60\u662f\u7528equals\u65b9\u6cd5\u5224\u65ad\u5bf9\u8c61\u7684\u5185\u5bb9\u662f\u5426\u76f8\u7b49\uff0c\u8bf7\u4e0d\u8981\u60f3\u5f53\u7136\u3002\u56e0\u4e3a\u53ef\u80fd\u4f60\u8ba4\u4e3a\u76f8\u7b49\uff0c\u800c\u8fd9\u4e2a\u7c7b\u7684\u4f5c\u8005\u4e0d\u8fd9\u6837\u8ba4\u4e3a\uff0c\u800c\u7c7b\u7684equals\u65b9\u6cd5\u7684\u5b9e\u73b0\u662f\u7531\u4ed6\u638c\u63e1\u7684\u3002\u5982\u679c\u4f60\u9700\u8981\u4f7f\u7528equals\u65b9\u6cd5\uff0c\u6216\u8005\u4f7f\u7528\u4efb\u4f55\u57fa\u4e8e\u6563\u5217\u7801\u7684\u96c6\u5408\uff08HashSet,HashMap,HashTable\uff09\uff0c\u8bf7\u5bdf\u770b\u4e00\u4e0bjava doc\u4ee5\u786e\u8ba4\u8fd9\u4e2a\u7c7b\u7684equals\u903b\u8f91\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u3002<\/p>\n
\u95ee\u9898\u4e09\uff1aString\u5230\u5e95\u53d8\u4e86\u6ca1\u6709\uff1f<\/p>\n
\u6ca1\u6709\u3002\u56e0\u4e3aString\u88ab\u8bbe\u8ba1\u6210\u4e0d\u53ef\u53d8(immutable)\u7c7b\uff0c\u6240\u4ee5\u5b83\u7684\u6240\u6709\u5bf9\u8c61\u90fd\u662f\u4e0d\u53ef\u53d8\u5bf9\u8c61\u3002\u8bf7\u770b\u4e0b\u5217\u4ee3\u7801\uff1a<\/p>\n
String s = “Hello”;
\ns = s + ” world!”;<\/p>\n
s\u6240\u6307\u5411\u7684\u5bf9\u8c61\u662f\u5426\u6539\u53d8\u4e86\u5462\uff1f\u4ece\u672c\u7cfb\u5217\u7b2c\u4e00\u7bc7\u7684\u7ed3\u8bba\u5f88\u5bb9\u6613\u5bfc\u51fa\u8fd9\u4e2a\u7ed3\u8bba\u3002\u6211\u4eec\u6765\u770b\u770b\u53d1\u751f\u4e86\u4ec0\u4e48\u4e8b\u60c5\u3002\u5728\u8fd9\u6bb5\u4ee3\u7801\u4e2d\uff0cs\u539f\u5148\u6307\u5411\u4e00\u4e2aString\u5bf9\u8c61\uff0c\u5185\u5bb9\u662f”Hello”\uff0c\u7136\u540e\u6211\u4eec\u5bf9s\u8fdb\u884c\u4e86+\u64cd\u4f5c\uff0c\u90a3\u4e48s\u6240\u6307\u5411\u7684\u90a3\u4e2a\u5bf9\u8c61\u662f\u5426\u53d1\u751f\u4e86\u6539\u53d8\u5462\uff1f\u7b54\u6848\u662f\u6ca1\u6709\u3002\u8fd9\u65f6\uff0cs\u4e0d\u6307\u5411\u539f\u6765\u90a3\u4e2a\u5bf9\u8c61\u4e86\uff0c\u800c\u6307\u5411\u4e86\u53e6\u4e00\u4e2aString\u5bf9\u8c61\uff0c\u5185\u5bb9\u4e3a”Hello world!”\uff0c\u539f\u6765\u90a3\u4e2a\u5bf9\u8c61\u8fd8\u5b58\u5728\u4e8e\u5185\u5b58\u4e4b\u4e2d\uff0c\u53ea\u662fs\u8fd9\u4e2a\u5f15\u7528\u53d8\u91cf\u4e0d\u518d\u6307\u5411\u5b83\u4e86\u3002 \u95ee\u9898\u56db\uff1afinal\u5173\u952e\u5b57\u5230\u5e95\u4fee\u9970\u4e86\u4ec0\u4e48\uff1f<\/p>\n final\u4f7f\u5f97\u88ab\u4fee\u9970\u7684\u53d8\u91cf”\u4e0d\u53d8”\uff0c\u4f46\u662f\u7531\u4e8e\u5bf9\u8c61\u578b\u53d8\u91cf\u7684\u672c\u8d28\u662f\u201c\u5f15\u7528\u201d\uff0c\u4f7f\u5f97\u201c\u4e0d\u53d8\u201d\u4e5f\u6709\u4e86\u4e24\u79cd\u542b\u4e49\uff1a\u5f15\u7528\u672c\u8eab\u7684\u4e0d\u53d8\uff0c\u548c\u5f15\u7528\u6307\u5411\u7684\u5bf9\u8c61\u4e0d\u53d8\u3002<\/p>\n \u5f15\u7528\u672c\u8eab\u7684\u4e0d\u53d8\uff1a \u5f15\u7528\u6307\u5411\u7684\u5bf9\u8c61\u4e0d\u53d8\uff1a \u53ef\u89c1\uff0cfinal\u53ea\u5bf9\u5f15\u7528\u7684\u201c\u503c\u201d(\u4e5f\u5373\u5b83\u6240\u6307\u5411\u7684\u90a3\u4e2a\u5bf9\u8c61\u7684\u5185\u5b58\u5730\u5740)\u6709\u6548\uff0c\u5b83\u8feb\u4f7f\u5f15\u7528\u53ea\u80fd\u6307\u5411\u521d\u59cb\u6307\u5411\u7684\u90a3\u4e2a\u5bf9\u8c61\uff0c\u6539\u53d8\u5b83\u7684\u6307\u5411\u4f1a\u5bfc\u81f4\u7f16\u8bd1\u671f\u9519\u8bef\u3002\u81f3\u4e8e\u5b83\u6240\u6307\u5411\u7684\u5bf9\u8c61\u7684\u53d8\u5316\uff0cfinal\u662f\u4e0d\u8d1f\u8d23\u7684\u3002\u8fd9\u5f88\u7c7b\u4f3c==\u64cd\u4f5c\u7b26\uff1a==\u64cd\u4f5c\u7b26\u53ea\u8d1f\u8d23\u5f15\u7528\u7684\u201c\u503c\u201d\u76f8\u7b49\uff0c\u81f3\u4e8e\u8fd9\u4e2a\u5730\u5740\u6240\u6307\u5411\u7684\u5bf9\u8c61\u5185\u5bb9\u662f\u5426\u76f8\u7b49\uff0c==\u64cd\u4f5c\u7b26\u662f\u4e0d\u7ba1\u7684\u3002<\/p>\n \u7406\u89e3final\u95ee\u9898\u6709\u5f88\u91cd\u8981\u7684\u542b\u4e49\u3002\u8bb8\u591a\u7a0b\u5e8f\u6f0f\u6d1e\u90fd\u57fa\u4e8e\u6b64—-final\u53ea\u80fd\u4fdd\u8bc1\u5f15\u7528\u6c38\u8fdc\u6307\u5411\u56fa\u5b9a\u5bf9\u8c61\uff0c\u4e0d\u80fd\u4fdd\u8bc1\u90a3\u4e2a\u5bf9\u8c61\u7684\u72b6\u6001\u4e0d\u53d8\u3002\u5728\u591a\u7ebf\u7a0b\u7684\u64cd\u4f5c\u4e2d,\u4e00\u4e2a\u5bf9\u8c61\u4f1a\u88ab\u591a\u4e2a\u7ebf\u7a0b\u5171\u4eab\u6216\u4fee\u6539\uff0c\u4e00\u4e2a\u7ebf\u7a0b\u5bf9\u5bf9\u8c61\u65e0\u610f\u8bc6\u7684\u4fee\u6539\u53ef\u80fd\u4f1a\u5bfc\u81f4\u53e6\u4e00\u4e2a\u4f7f\u7528\u6b64\u5bf9\u8c61\u7684\u7ebf\u7a0b\u5d29\u6e83\u3002\u4e00\u4e2a\u9519\u8bef\u7684\u89e3\u51b3\u65b9\u6cd5\u5c31\u662f\u5728\u6b64\u5bf9\u8c61\u65b0\u5efa\u7684\u65f6\u5019\u628a\u5b83\u58f0\u660e\u4e3afinal\uff0c\u610f\u56fe\u4f7f\u5f97\u5b83\u201c\u6c38\u8fdc\u4e0d\u53d8\u201d\u3002\u5176\u5b9e\u90a3\u662f\u5f92\u52b3\u7684\u3002<\/p>\n \u95ee\u9898\u4e94\uff1a\u5230\u5e95\u8981\u600e\u4e48\u6837\u521d\u59cb\u5316\uff01<\/p>\n \u672c\u95ee\u9898\u8ba8\u8bba\u53d8\u91cf\u7684\u521d\u59cb\u5316\uff0c\u6240\u4ee5\u5148\u6765\u770b\u4e00\u4e0bJava\u4e2d\u6709\u54ea\u4e9b\u79cd\u7c7b\u7684\u53d8\u91cf\u3002 \u5bf9\u4e8e\u7b2c\u4e00\u79cd\u53d8\u91cf\uff0cJava\u865a\u62df\u673a\u4f1a\u81ea\u52a8\u8fdb\u884c\u521d\u59cb\u5316\u3002\u5982\u679c\u7ed9\u51fa\u4e86\u521d\u59cb\u503c\uff0c\u5219\u521d\u59cb\u5316\u4e3a\u8be5\u521d\u59cb\u503c\u3002\u5982\u679c\u6ca1\u6709\u7ed9\u51fa\uff0c\u5219\u628a\u5b83\u521d\u59cb\u5316\u4e3a\u8be5\u7c7b\u578b\u53d8\u91cf\u7684\u9ed8\u8ba4\u521d\u59cb\u503c\u3002<\/p>\n int\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3a0 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\u5176\u5b9e\u7b2c\u4e09\u79cd\u53d8\u91cf\u548c\u7b2c\u4e8c\u79cd\u672c\u8d28\u4e0a\u662f\u4e00\u6837\u7684\uff0c\u90fd\u662f\u65b9\u6cd5\u4e2d\u7684\u5c40\u90e8\u53d8\u91cf\u3002\u53ea\u4e0d\u8fc7\u4f5c\u4e3a\u53c2\u6570\uff0c\u80af\u5b9a\u662f\u88ab\u521d\u59cb\u5316\u8fc7\u7684\uff0c\u4f20\u5165\u7684\u503c\u5c31\u662f\u521d\u59cb\u503c\uff0c\u6240\u4ee5\u4e0d\u9700\u8981\u521d\u59cb\u5316\u3002<\/p>\n \u95ee\u9898\u516d\uff1ainstanceof\u662f\u4ec0\u4e48\u4e1c\u4e1c\uff1f<\/p>\n instanceof\u662fJava\u7684\u4e00\u4e2a\u4e8c\u5143\u64cd\u4f5c\u7b26\uff0c\u548c==\uff0c>\uff0c<\u662f\u540c\u4e00\u7c7b\u4e1c\u4e1c\u3002\u7531\u4e8e\u5b83\u662f\u7531\u5b57\u6bcd\u7ec4\u6210\u7684\uff0c\u6240\u4ee5\u4e5f\u662fJava\u7684\u4fdd\u7559\u5173\u952e\u5b57\u3002\u5b83\u7684\u4f5c\u7528\u662f\u6d4b\u8bd5\u5b83\u5de6\u8fb9\u7684\u5bf9\u8c61\u662f\u5426\u662f\u5b83\u53f3\u8fb9\u7684\u7c7b\u7684\u5b9e\u4f8b\uff0c\u8fd4\u56deboolean\u7c7b\u578b\u7684\u6570\u636e\u3002\u4e3e\u4e2a\u4f8b\u5b50\uff1a\n\nString s = \"I AM an Object!\";\nboolean isObject = s instanceof Object;\n\n\u6211\u4eec\u58f0\u660e\u4e86\u4e00\u4e2aString\u5bf9\u8c61\u5f15\u7528\uff0c\u6307\u5411\u4e00\u4e2aString\u5bf9\u8c61\uff0c\u7136\u540e\u7528instancof\u6765\u6d4b\u8bd5\u5b83\u6240\u6307\u5411\u7684\u5bf9\u8c61\u662f\u5426\u662fObject\u7c7b\u7684\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u663e\u7136\uff0c\u8fd9\u662f\u771f\u7684\uff0c\u6240\u4ee5\u8fd4\u56detrue\uff0c\u4e5f\u5c31\u662fisObject\u7684\u503c\u4e3aTrue\u3002\ninstanceof\u6709\u4e00\u4e9b\u7528\u5904\u3002\u6bd4\u5982\u6211\u4eec\u5199\u4e86\u4e00\u4e2a\u5904\u7406\u8d26\u5355\u7684\u7cfb\u7edf\uff0c\u5176\u4e2d\u6709\u8fd9\u6837\u4e09\u4e2a\u7c7b\uff1a\n\npublic class Bill {\/\/\u7701\u7565\u7ec6\u8282}\npublic class PhoneBill extends Bill {\/\/\u7701\u7565\u7ec6\u8282}\npublic class GasBill extends Bill {\/\/\u7701\u7565\u7ec6\u8282}\n\n\u5728\u5904\u7406\u7a0b\u5e8f\u91cc\u6709\u4e00\u4e2a\u65b9\u6cd5\uff0c\u63a5\u53d7\u4e00\u4e2aBill\u7c7b\u578b\u7684\u5bf9\u8c61\uff0c\u8ba1\u7b97\u91d1\u989d\u3002\u5047\u8bbe\u4e24\u79cd\u8d26\u5355\u8ba1\u7b97\u65b9\u6cd5\u4e0d\u540c\uff0c\u800c\u4f20\u5165\u7684Bill\u5bf9\u8c61\u53ef\u80fd\u662f\u4e24\u79cd\u4e2d\u7684\u4efb\u4f55\u4e00\u79cd\uff0c\u6240\u4ee5\u8981\u7528instanceof\u6765\u5224\u65ad\uff1a\n\n[java]public double calculate(Bill bill) {\n if (bill instanceof PhoneBill) {\n \/\/\u8ba1\u7b97\u7535\u8bdd\u8d26\u5355\n }\n if (bill instanceof GasBill) {\n \/\/\u8ba1\u7b97\u71c3\u6c14\u8d26\u5355\n }\n ...\n}[\/java]\n\u8fd9\u6837\u5c31\u53ef\u4ee5\u7528\u4e00\u4e2a\u65b9\u6cd5\u5904\u7406\u4e24\u79cd\u5b50\u7c7b\u3002\n\n\u7136\u800c\uff0c\u8fd9\u79cd\u505a\u6cd5\u901a\u5e38\u88ab\u8ba4\u4e3a\u662f\u6ca1\u6709\u597d\u597d\u5229\u7528\u9762\u5411\u5bf9\u8c61\u4e2d\u7684\u591a\u6001\u6027\u3002\u5176\u5b9e\u4e0a\u9762\u7684\u529f\u80fd\u8981\u6c42\u7528\u65b9\u6cd5\u91cd\u8f7d\u5b8c\u5168\u53ef\u4ee5\u5b9e\u73b0\uff0c\u8fd9\u662f\u9762\u5411\u5bf9\u8c61\u53d8\u6210\u5e94\u6709\u7684\u505a\u6cd5\uff0c\u907f\u514d\u56de\u5230\u7ed3\u6784\u5316\u7f16\u7a0b\u6a21\u5f0f\u3002\u53ea\u8981\u63d0\u4f9b\u4e24\u4e2a\u540d\u5b57\u548c\u8fd4\u56de\u503c\u90fd\u76f8\u540c\uff0c\u63a5\u53d7\u53c2\u6570\u7c7b\u578b\u4e0d\u540c\u7684\u65b9\u6cd5\u5c31\u53ef\u4ee5\u4e86\uff1a\n[java]\npublic double calculate(PhoneBill bill) {\n \/\/\u8ba1\u7b97\u7535\u8bdd\u8d26\u5355\n}\npublic double calculate(GasBill bill) {\n \/\/\u8ba1\u7b97\u71c3\u6c14\u8d26\u5355\n}[\/java]\n\n\u6240\u4ee5\uff0c\u4f7f\u7528instanceof\u5728\u7edd\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u5e76\u4e0d\u662f\u63a8\u8350\u7684\u505a\u6cd5\uff0c\u5e94\u5f53\u597d\u597d\u5229\u7528\u591a\u6001\u3002\n\n<\/p>\n","protected":false},"excerpt":{"rendered":" \u5bf9\u4e8e\u8fd9\u4e2a\u7cfb\u5217\u91cc\u7684\u95ee\u9898\uff0c\u6bcf\u4e2a\u5b66Java\u7684\u4eba\u90fd\u5e94\u8be5\u641e\u61c2\u3002\u5f53\u7136\uff0c\u5982\u679c\u53ea\u662f\u5b66Java\u73a9\u73a9\u5c31\u65e0\u6240\u8c13\u4e86\u3002\u5982\u679c\u4f60\u8ba4\u4e3a\u81ea\u5df1\u5df2\u7ecf […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[46],"tags":[],"_links":{"self":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/589"}],"collection":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=589"}],"version-history":[{"count":3,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/589\/revisions"}],"predecessor-version":[{"id":592,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/589\/revisions\/592"}],"wp:attachment":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=589"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=589"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=589"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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\n[java]public class Demo {
\n private String s;
\n …
\n public Demo {
\n s = "Initial Value";
\n }
\n …
\n}[\/java]
\n\u800c\u975e
\ns = new String(“Initial Value”);
\n\u540e\u8005\u6bcf\u6b21\u90fd\u4f1a\u8c03\u7528\u6784\u9020\u5668\uff0c\u751f\u6210\u65b0\u5bf9\u8c61\uff0c\u6027\u80fd\u4f4e\u4e0b\u4e14\u5185\u5b58\u5f00\u9500\u5927\uff0c\u5e76\u4e14\u6ca1\u6709\u610f\u4e49\uff0c\u56e0\u4e3aString\u5bf9\u8c61\u4e0d\u53ef\u6539\u53d8\uff0c\u6240\u4ee5\u5bf9\u4e8e\u5185\u5bb9\u76f8\u540c\u7684\u5b57\u7b26\u4e32\uff0c\u53ea\u8981\u4e00\u4e2aString\u5bf9\u8c61\u6765\u8868\u793a\u5c31\u53ef\u4ee5\u4e86\u3002\u4e5f\u5c31\u8bf4\uff0c\u591a\u6b21\u8c03\u7528\u4e0a\u9762\u7684\u6784\u9020\u5668\u521b\u5efa\u591a\u4e2a\u5bf9\u8c61\uff0c\u4ed6\u4eec\u7684String\u7c7b\u578b\u5c5e\u6027s\u90fd\u6307\u5411\u540c\u4e00\u4e2a\u5bf9\u8c61\u3002
\n\u4e0a\u9762\u7684\u7ed3\u8bba\u8fd8\u57fa\u4e8e\u8fd9\u6837\u4e00\u4e2a\u4e8b\u5b9e\uff1a\u5bf9\u4e8e\u5b57\u7b26\u4e32\u5e38\u91cf\uff0c\u5982\u679c\u5185\u5bb9\u76f8\u540c\uff0cJava\u8ba4\u4e3a\u5b83\u4eec\u4ee3\u8868\u540c\u4e00\u4e2aString\u5bf9\u8c61\u3002<\/strong>\u800c\u7528\u5173\u952e\u5b57new\u8c03\u7528\u6784\u9020\u5668\uff0c\u603b\u662f\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\uff0c\u65e0\u8bba\u5185\u5bb9\u662f\u5426\u76f8\u540c\u3002
\n\u81f3\u4e8e\u4e3a\u4ec0\u4e48\u8981\u628aString\u7c7b\u8bbe\u8ba1\u6210\u4e0d\u53ef\u53d8\u7c7b\uff0c\u662f\u5b83\u7684\u7528\u9014\u51b3\u5b9a\u7684\u3002\u5176\u5b9e\u4e0d\u53eaString\uff0c\u5f88\u591aJava\u6807\u51c6\u7c7b\u5e93\u4e2d\u7684\u7c7b\u90fd\u662f\u4e0d\u53ef\u53d8\u7684\u3002\u5728\u5f00\u53d1\u4e00\u4e2a\u7cfb\u7edf\u7684\u65f6\u5019\uff0c\u6211\u4eec\u6709\u65f6\u5019\u4e5f\u9700\u8981\u8bbe\u8ba1\u4e0d\u53ef\u53d8\u7c7b\uff0c\u6765\u4f20\u9012\u4e00\u7ec4\u76f8\u5173\u7684\u503c\uff0c\u8fd9\u4e5f\u662f\u9762\u5411\u5bf9\u8c61\u601d\u60f3\u7684\u4f53\u73b0\u3002\u4e0d\u53ef\u53d8\u7c7b\u6709\u4e00\u4e9b\u4f18\u70b9\uff0c\u6bd4\u5982\u56e0\u4e3a\u5b83\u7684\u5bf9\u8c61\u662f\u53ea\u8bfb\u7684\uff0c\u6240\u4ee5\u591a\u7ebf\u7a0b\u5e76\u53d1\u8bbf\u95ee\u4e5f\u4e0d\u4f1a\u6709\u4efb\u4f55\u95ee\u9898\u3002\u5f53\u7136\u4e5f\u6709\u4e00\u4e9b\u7f3a\u70b9\uff0c\u6bd4\u5982\u6bcf\u4e2a\u4e0d\u540c\u7684\u72b6\u6001\u90fd\u8981\u4e00\u4e2a\u5bf9\u8c61\u6765\u4ee3\u8868\uff0c\u53ef\u80fd\u4f1a\u9020\u6210\u6027\u80fd\u4e0a\u7684\u95ee\u9898\u3002\u6240\u4ee5Java\u6807\u51c6\u7c7b\u5e93\u8fd8\u63d0\u4f9b\u4e86\u4e00\u4e2a\u53ef\u53d8\u7248\u672c\uff0c\u5373StringBuffer\u3002<\/p>\n
\nfinal StringBuffer a=new StringBuffer(“immutable”);
\nfinal StringBuffer b=new StringBuffer(“not immutable”);
\na=b;\/\/\u7f16\u8bd1\u671f\u9519\u8bef<\/p>\n
\nfinal StringBuffer a=new StringBuffer(“immutable”);
\na.append(” broken!”); \/\/\u7f16\u8bd1\u901a\u8fc7<\/p>\n
\n1. \u7c7b\u7684\u5c5e\u6027\uff0c\u6216\u8005\u53eb\u503c\u57df
\n2. \u65b9\u6cd5\u91cc\u7684\u5c40\u90e8\u53d8\u91cf
\n3. \u65b9\u6cd5\u7684\u53c2\u6570<\/p>\n
\nfloat\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3a0.0f
\ndouble\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3a0.0
\nboolean\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3afalse
\nchar\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3a0(ASCII\u7801)
\nlong\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3a0
\n\u6240\u6709\u5bf9\u8c61\u5f15\u7528\u7c7b\u578b\u53d8\u91cf\u9ed8\u8ba4\u521d\u59cb\u503c\u4e3anull\uff0c\u5373\u4e0d\u6307\u5411\u4efb\u4f55\u5bf9\u8c61\u3002\u6ce8\u610f\u6570\u7ec4\u672c\u8eab\u4e5f\u662f\u5bf9\u8c61\uff0c\u6240\u4ee5\u6ca1\u6709\u521d\u59cb\u5316\u7684\u6570\u7ec4\u5f15\u7528\u5728\u81ea\u52a8\u521d\u59cb\u5316\u540e\u5176\u503c\u4e5f\u662fnull\u3002<\/p>\n