{"id":4630,"date":"2019-10-21T00:55:50","date_gmt":"2019-10-20T15:55:50","guid":{"rendered":"https:\/\/chat-messenger.com\/?p=4630"},"modified":"2023-11-13T01:14:20","modified_gmt":"2023-11-12T16:14:20","slug":"java-instanceof","status":"publish","type":"post","link":"https:\/\/chat-messenger.com\/zh\/\u535a\u5ba2\/java\/java-instanceof","title":{"rendered":"\u4f7f\u7528 instanceof \u68c0\u67e5 Java \u53d8\u91cf\u7684\u7c7b\u578b"},"content":{"rendered":"

\u68c0\u67e5\u53d8\u91cf\u7c7b\u578b<\/h2>\n\n\n\n

\u4e0b\u9762\u662f\u4e00\u4e2a\u7528 Java \u68c0\u67e5\u53d8\u91cf\u7c7b\u578b\u7684\u793a\u4f8b\u7a0b\u5e8f\u3002<\/p>\n\n\n\n

\u7531\u4e8e Java \u662f\u4e00\u79cd\u9759\u6001\u7c7b\u578b\u8bed\u8a00\uff0c\u7c7b\u578b\u662f\u663e\u5f0f\u58f0\u660e\u7684\uff0c\u56e0\u6b64\u6ca1\u6709\u673a\u4f1a\u5728\u8fd9\u79cd\u7a0b\u5ea6\u4e0a\u68c0\u67e5\u7c7b\u578b\u3002\u4e0d\u8fc7\uff0c\u5728\u4f7f\u7528\u7ee7\u627f\u5bf9\u8c61\u65f6\uff0c\u53ef\u80fd\u6709\u5fc5\u8981\u8fdb\u884c\u7c7b\u578b\u68c0\u67e5\u3002<\/p>\n\n\n\n

\u5982\u4f55\u68c0\u67e5 Java \u4e2d\u7684\u7c7b\u578b \u5b9e\u4f8b<\/strong> \u4f7f\u7528\u8fd0\u7b97\u7b26\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 if \u8bed\u53e5\u7b49\u8bc4\u4f30\u7c7b\u548c\u63a5\u53e3\uff0c\u5982\u4e0b\u6240\u793a\u3002<\/p>\n\n\n\n

\n

\u591a\u53d8\u7684<\/em> \u7c7b\u7684\u5b9e\u4f8b<\/p>\n\n\n\n

\u591a\u53d8\u7684<\/em> \u63a5\u53e3\u5b9e\u4f8b<\/p>\n<\/div><\/div>\n\n\n\n

\u5b9e\u4f8b<\/strong> \u7684\u53f3\u4fa7\u53ef\u4ee5\u6307\u5b9a\u7c7b\u540d\u6216\u63a5\u53e3\u540d\u3002\u5b9e\u4f8b<\/strong> \u8fd4\u56de\u503c\u662f\u4e00\u4e2a\u5e03\u5c14\u503c\uff1b\u5982\u679c\u4e3a true\uff0c\u5219\u53d8\u91cf\u662f\u6307\u5b9a\u7684\u7c7b\u6216\u63a5\u53e3\u3002<\/p>\n\n\n\n

\n

\u804a\u5929&\u4fe1\u4f7f<\/a> \u662f\u4e00\u6b3e\u96c6\u5546\u52a1\u804a\u5929\u3001\u7f51\u7edc\u4f1a\u8bae\u3001\u6587\u4ef6\u5171\u4eab\u3001\u65e5\u7a0b\u7ba1\u7406\u3001\u6587\u6863\u7ba1\u7406\u3001\u4f1a\u8bae\u5ba4\u9884\u8ba2\u3001\u8003\u52e4\u7ba1\u7406\u4e8e\u4e00\u4f53\u7684\u7ec4\u4ef6\uff0c\u7b80\u5355\u6613\u7528\u3002\u4e3a\u4f01\u4e1a\u63d0\u4f9b\u5b8c\u5584\u7684\u5b89\u5168\u4fdd\u62a4\uff0c\u514d\u8d39\u63d0\u4f9b\uff01<\/mark><\/p>\n<\/a>\n<\/div>\n\n\n\n

\u793a\u4f8b\u7a0b\u5e8f<\/h2>\n\n\n\n

\u9996\u5148\u662f\u6700\u7b80\u5355\u7684\u6a21\u5f0f\u3002\u5982\u679c\u53d8\u91cf i \u662f\u6574\u6570\uff0c\u5219\u8fd4\u56de true\uff0c\u5426\u5219\u8fd4\u56de false\u3002<\/p>\n\n\n\n

\u793a\u4f8b\u4ee3\u7801<\/h4>\n\n\n\n
public static void integerSample() {\n    Integer i = 100;\n    boolean result = i instanceof Integer;\n    System.out.println(result);\n}<\/code><\/pre><\/div>\n\n\n\n
\u8f93\u51fa\uff08\u7ed3\u679c\uff09<\/h4>\n\n\n\n
true<\/code><\/pre><\/div>\n\n\n\n
\u53d8\u91cf i \u662f\u4e00\u4e2a\u6574\u6570\uff0c\u56e0\u6b64\u7ed3\u679c\u4e3a true\u3002\u4e0d\u8fc7\uff0c\u8fd9\u592a\u660e\u663e\u4e86\uff0c\u6211\u4eec\u65e0\u6cd5\u7406\u89e3 instanceof \u7684\u4f5c\u7528\uff0c\u6240\u4ee5\u6211\u4eec\u518d\u628a\u5b83\u590d\u6742\u5316\u4e00\u70b9\u3002<\/p>\n\n\n\n
\u6709\u6548\u4f7f\u7528\u5b9e\u4f8b<\/h2>\n\n\n\n
instanceof \u7684\u4e00\u4e2a\u6709\u6548\u7528\u6cd5\u662f\u786e\u5b9a\u53d8\u91cf\u662f\u54ea\u4e2a\u5b50\u7c7b\u3002<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801<\/h4>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u52a8\u7269\u7c7bAnimal\u3001\u4e00\u4e2a\u7ee7\u627f\u4e8eAnimal\u7c7b\u7684Dog\u7c7b\u3001\u4ee5\u53ca\u4e00\u4e2aCat\u7c7b\uff0c\u521b\u5efa\u5b9e\u4f8b\u540e\uff0c\u6211\u4eec\u5728play\u65b9\u6cd5\u4e2d\u8bbe\u7f6e\u4e86\u4e00\u4e2a\u53d8\u91cf\u3002 \u5b9e\u4f8b<\/strong> \u63a7\u5236\u53f0\u8f93\u51fa\u6839\u636e\u5224\u65ad\u8fdb\u884c\u5206\u652f\u3002 <\/p>\n\n\n\n
class Animal {} \nclass Dog extends Animal {}\nclass Cat extends Animal {}\n\npublic class Main {\n    public static void main(String[] args) {\n        instanceofSample();\n    }\n    \n    static void instanceofSample() {\n        Animal dog = new Dog();\n        play(dog);\n        Animal cat = new Cat();\n        play(cat);\n    }\n    \n    static void play(Animal animal) {\n        if (animal instanceof Dog) {\n            System.out.println("\u304a\u6563\u6b69\u3059\u308b");\n        } else {\n            System.out.println("\u732b\u3058\u3083\u3089\u3057\u3067\u904a\u3076");\n        }\n    }\n}<\/code><\/pre><\/div>\n\n\n\n
\u8f93\u51fa\uff08\u7ed3\u679c\uff09<\/h4>\n\n\n\n
\u304a\u6563\u6b69\u3059\u308b\n\u732b\u3058\u3083\u3089\u3057\u3067\u904a\u3076<\/code><\/pre><\/div>\n\n\n\n
\u5173\u952e\u5728\u4e8e\uff0c\u5728\u6e38\u620f\u65b9\u6cd5\u4e2d\uff0c\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u7684\u52a8\u7269\u662f\u72d7\u8fd8\u662f\u732b\u5e76\u4e0d\u53ef\u77e5\u3002<\/p>\n\n\n\n
\u5b9e\u4f8b<\/strong> \u73b0\u5728\uff0c\u60a8\u8fd8\u53ef\u4ee5\u68c0\u67e5\u8d85\u7c7b\uff08\u52a8\u7269\uff09\u4e2d\u5305\u542b\u7684\u5b50\u7c7b\u5b9e\u4f8b\uff08\u72d7\u6216\u732b\uff09\uff0c\u56e0\u6b64\u60a8\u53ef\u4ee5\u50cf\u8fd9\u6837\u4f7f\u7528\u5b83\u3002<\/p>\n\n\n\n
\u68c0\u67e5\u7279\u5b9a\u63a5\u53e3\u662f\u5426\u5df2\u88ab\u5b9e\u73b0<\/h2>\n\n\n\n
\u60a8\u53ef\u4ee5\u68c0\u67e5instanceof\u6240\u9488\u5bf9\u7684\u53d8\u91cf\u662f\u5426\u5b9e\u73b0\u4e86\u7279\u5b9a\u63a5\u53e3\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u8fd9\u6837\u4f7f\u7528\u5b83\u3002<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801<\/h4>\n\n\n\n
\u5728\u4e0b\u9762\u7684\u793a\u4f8b\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u4e3a Sato \u5148\u751f\u548c Suzuki \u5148\u751f\u521b\u5efa\u7c7b\uff0c\u5e76\u5b9e\u73b0 Car \u63a5\u53e3\uff0c\u5047\u8bbe\u53ea\u6709 Suzuki \u5148\u751f\u62e5\u6709\u6c7d\u8f66\u3002 goShopping() \u65b9\u6cd5\u5047\u8bbe\u53bb\u8d2d\u7269\u7684\u8fc7\u7a0b\uff0c\u4f46\u5b83\u5b9e\u73b0\u4e86 Car \u6216\u57fa\u4e8e instanceof \u5206\u652f\u63a7\u5236\u53f0\u8f93\u51fa\u3002<\/p>\n\n\n\n
interface Car {}\nclass Sato {}\nclass Suzuki implements Car {}\n\npublic class Main {\n    public static void main(String[] args) throws Exception {\n        instanceofSample();\n    }\n    \n    static void instanceofSample() {\n        Sato sato = new Sato();\n        goShopping(sato);\n\n        Suzuki suzuki = new Suzuki();\n        goShopping(suzuki);\n    }\n    \n    static void goShopping(Object human) {\n        if (human instanceof Car) {\n            System.out.println("\u8eca\u3067\u884c\u304f");\n        } else {\n            System.out.println("\u6b69\u3044\u3066\u884c\u304f");\n        }\n    }\n}<\/code><\/pre><\/div>\n\n\n\n
\u8f93\u51fa\u7ed3\u679c\uff1a<\/h4>\n\n\n\n
\u6b69\u3044\u3066\u884c\u304f\n\u8eca\u3067\u884c\u304f<\/code><\/pre><\/div>\n\n\n\n
\u53ef\u4ee5\u770b\u51fa\uff0c\u5728\u5b9e\u65bd Car \u548c\u4e0d\u5b9e\u65bd Car \u7684\u60c5\u51b5\u4e0b\uff0c\u6d41\u7a0b\u662f\u4e0d\u540c\u7684\u3002<\/p>","protected":false},"excerpt":{"rendered":"
\u68c0\u67e5\u53d8\u91cf\u7684\u7c7b\u578b \u4ecb\u7ecd\u4e00\u4e2a\u5728 Java \u4e2d\u68c0\u67e5\u53d8\u91cf\u7c7b\u578b\u7684\u793a\u4f8b\u7a0b\u5e8f\u3002 Java \u663e\u5f0f\u58f0\u660e\u7c7b\u578b [...]<\/p>","protected":false},"author":1,"featured_media":9054,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"swell_btn_cv_data":""},"categories":[19],"tags":[],"_links":{"self":[{"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/posts\/4630"}],"collection":[{"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/comments?post=4630"}],"version-history":[{"count":6,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/posts\/4630\/revisions"}],"predecessor-version":[{"id":9049,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/posts\/4630\/revisions\/9049"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/media\/9054"}],"wp:attachment":[{"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/media?parent=4630"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/categories?post=4630"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/tags?post=4630"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}