{"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_tw\/\u90e8\u843d\u683c\/java\/java\u5be6\u4f8b\u5316","title":{"rendered":"\u4f7f\u7528 instanceof \u68c0\u67e5 Java \u53d8\u91cf\u7684\u7c7b\u578b"},"content":{"rendered":"

\u6aa2\u67e5\u8b8a\u6578\u985e\u578b<\/h2>\n\n\n\n

\u4ecb\u7d39\u4e00\u500b\u5728 Java \u4e2d\u6aa2\u67e5\u8b8a\u6578\u985e\u578b\u7684\u7bc4\u4f8b\u7a0b\u5f0f\u3002<\/p>\n\n\n\n

Java \u662f\u4e00\u7a2e\u660e\u78ba\u5ba3\u544a\u985e\u578b\u7684\u975c\u614b\u578b\u5225\u8a9e\u8a00\uff0c\u56e0\u6b64\u6c92\u6709\u6a5f\u6703\u6aa2\u67e5\u592a\u591a\u578b\u5225\u3002\u7136\u800c\uff0c\u5728\u4f7f\u7528\u7e7c\u627f\u7684\u7269\u4ef6\u6642\uff0c\u985e\u578b\u6aa2\u67e5\u53ef\u80fd\u662f\u5fc5\u8981\u7684\u3002<\/p>\n\n\n\n

\u5982\u4f55\u6aa2\u67e5 Java \u4e2d\u7684\u985e\u578b \u5be6\u4f8b\u5316<\/strong> \u4f7f\u7528\u904b\u7b97\u7b26\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 if \u8a9e\u53e5\u7b49\u8a55\u4f30\u985e\u5225\u548c\u63a5\u53e3\uff0c\u5982\u4e0b\u6240\u793a\u3002<\/p>\n\n\n\n

\n

\u591a\u8b8a\u7684<\/em> \u985e\u5225\u7684\u5be6\u4f8b<\/p>\n\n\n\n

\u591a\u8b8a\u7684<\/em> \u4ecb\u9762\u5be6\u4f8b<\/p>\n<\/div><\/div>\n\n\n\n

\u5be6\u4f8b\u5316<\/strong> \u7684\u53f3\u5074\u53ef\u4ee5\u6307\u5b9a\u985e\u5225\u540d\u7a31\u6216\u4ecb\u9762\u540d\u7a31\u3002\u5be6\u4f8b\u5316<\/strong> \u50b3\u56de\u503c\u662f\u4e00\u500b\u5e03\u6797\u503c\uff1b\u5982\u679c\u70ba true\uff0c\u5247\u8b8a\u6578\u662f\u6307\u5b9a\u7684\u985e\u5225\u6216\u4ecb\u9762\u3002<\/p>\n\n\n\n

\n

\u804a\u5929&\u4fe1\u4f7f<\/a> \u662f\u4e00\u6b3e\u96c6\u5546\u52d9\u804a\u5929\u3001\u7db2\u8def\u6703\u8b70\u3001\u6587\u4ef6\u5206\u4eab\u3001\u884c\u7a0b\u7ba1\u7406\u3001\u6587\u4ef6\u7ba1\u7406\u3001\u6703\u8b70\u5ba4\u9810\u7d04\u3001\u8003\u52e4\u7ba1\u7406\u65bc\u4e00\u9ad4\u7684\u5143\u4ef6\uff0c\u7c21\u55ae\u6613\u7528\u3002\u70ba\u4f01\u696d\u63d0\u4f9b\u5b8c\u5584\u7684\u5b89\u5168\u4fdd\u8b77\uff0c\u514d\u8cbb\u63d0\u4f9b\uff01<\/mark><\/p>\n<\/a>\n<\/div>\n\n\n\n

\u7bc4\u4f8b\u7a0b\u5f0f<\/h2>\n\n\n\n

\u8b93\u6211\u5011\u5f9e\u6700\u7c21\u55ae\u7684\u6a21\u5f0f\u958b\u59cb\u3002\u5982\u679c\u8b8a\u6578 i \u662f\u6574\u6578\uff0c\u5247\u50b3\u56de true\uff0c\u5426\u5247\u50b3\u56de false\u3002<\/p>\n\n\n\n

\u7bc4\u4f8b\u7a0b\u5f0f\u78bc<\/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
\u8f38\u51fa\u7d50\u679c<\/h4>\n\n\n\n
true<\/code><\/pre><\/div>\n\n\n\n
\u8b8a\u6578 i \u662f Integer\uff0c\u6240\u4ee5\u7d50\u679c\u70ba true\u3002\u7136\u800c\uff0c\u9019\u592a\u660e\u986f\u4e86\uff0c\u6211\u4e0d\u77e5\u9053instanceof\u662f\u505a\u4ec0\u9ebc\u7528\u7684\uff0c\u6240\u4ee5\u8b93\u6211\u5011\u628a\u5b83\u5f04\u5f97\u66f4\u8907\u96dc\u4e00\u4e9b\u3002<\/p>\n\n\n\n
\u6709\u6548\u4f7f\u7528instanceof<\/h2>\n\n\n\n
instanceof \u7684\u4e00\u500b\u6709\u6548\u7528\u9014\u662f\u78ba\u5b9a\u8b8a\u6578\u5c6c\u65bc\u54ea\u500b\u5b50\u985e\u5225\u3002<\/p>\n\n\n\n
\u7bc4\u4f8b\u7a0b\u5f0f\u78bc<\/h4>\n\n\n\n
\u5728\u7bc4\u4f8b\u7a0b\u5f0f\u78bc\u4e2d\uff0c\u6211\u5011\u5275\u5efa\u4e86\u4e00\u500b\u52d5\u7269\u985eAnimal\u3001\u4e00\u500b\u7e7c\u627f\u65bc\u8a72\u52d5\u7269\u985e\u7684Dog\u985e\u3001\u4ee5\u53ca\u4e00\u500bCat\u985e\uff0c\u4e26\u5728\u5275\u5efa\u5be6\u4f8b\u5f8c\uff0c\u5728play\u65b9\u6cd5\u4e2d\u8a2d\u5b9a\u8b8a\u6578\u3002 \u5be6\u4f8b\u5316<\/strong> \u63a7\u5236\u53f0\u8f38\u51fa\u6839\u64da\u5224\u65b7\u9032\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
\u8f38\u51fa\u7d50\u679c<\/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
play \u65b9\u6cd5\u7684\u95dc\u9375\u9ede\u5728\u65bc\uff0c\u4e0d\u6e05\u695a\u4f5c\u70ba\u53c3\u6578\u50b3\u905e\u7684\u52d5\u7269\u662f\u72d7\u9084\u662f\u8c93\u3002<\/p>\n\n\n\n
\u5be6\u4f8b\u5316<\/strong> \u73fe\u5728\uff0c\u60a8\u4e5f\u53ef\u4ee5\u6aa2\u67e5\u8d85\u985e\u5225\uff08\u52d5\u7269\uff09\u4e2d\u5305\u542b\u7684\u5b50\u985e\u5225\u5be6\u4f8b\uff08\u72d7\u6216\u8c93\uff09\uff0c\u56e0\u6b64\u60a8\u53ef\u4ee5\u50cf\u9019\u6a23\u4f7f\u7528\u5b83\u3002<\/p>\n\n\n\n
\u6aa2\u67e5\u7279\u5b9a\u4ecb\u9762\u662f\u5426\u5df2\u5be6\u73fe<\/h2>\n\n\n\n
\u60a8\u53ef\u4ee5\u6aa2\u67e5instanceof\u6240\u91dd\u5c0d\u7684\u8b8a\u6578\u662f\u5426\u5be6\u4f5c\u4e86\u7279\u5b9a\u4ecb\u9762\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u9019\u6a23\u4f7f\u7528\u5b83\u3002<\/p>\n\n\n\n
\u7bc4\u4f8b\u7a0b\u5f0f\u78bc<\/h4>\n\n\n\n
\u5728\u4e0b\u9762\u7684\u7bc4\u4f8b\u7a0b\u5f0f\u78bc\u4e2d\uff0c\u5275\u5efa\u4e86 Sato \u5148\u751f\u548c Suzuki \u5148\u751f\u7684\u985e\uff0c\u4e26\u5047\u8a2d\u53ea\u6709 Suzuki \u5148\u751f\u64c1\u6709\u6c7d\u8eca\uff0c\u4e26\u5be6\u73fe\u4e86 Car \u4ecb\u9762\u3002 goShopping() \u65b9\u6cd5\u5047\u8a2d\u53bb\u8cfc\u7269\u7684\u904e\u7a0b\uff0c\u4f46\u5b83\u5be6\u4f5c\u4e86 Car \u6216\u57fa\u65bc instanceof \u5206\u652f\u63a7\u5236\u53f0\u8f38\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
\u8f38\u51fa\u7d50\u679c\uff1a<\/h4>\n\n\n\n
\u6b69\u3044\u3066\u884c\u304f\n\u8eca\u3067\u884c\u304f<\/code><\/pre><\/div>\n\n\n\n
\u60a8\u53ef\u4ee5\u770b\u5230\u8655\u7406\u5206\u652f\u53d6\u6c7a\u65bc Car \u662f\u5426\u5be6\u73fe\u3002<\/p>","protected":false},"excerpt":{"rendered":"
\u6aa2\u67e5\u8b8a\u6578\u7684\u985e\u578b \u4ecb\u7d39\u4e00\u500b\u5728 Java \u4e2d\u6aa2\u67e5\u8b8a\u6578\u985e\u578b\u7684\u7bc4\u4f8b\u7a0b\u5f0f\u3002 Java \u660e\u78ba\u5ba3\u544a\u985e\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_tw\/wp-json\/wp\/v2\/posts\/4630"}],"collection":[{"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/comments?post=4630"}],"version-history":[{"count":6,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/posts\/4630\/revisions"}],"predecessor-version":[{"id":9049,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/posts\/4630\/revisions\/9049"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/media\/9054"}],"wp:attachment":[{"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/media?parent=4630"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/categories?post=4630"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/chat-messenger.com\/zh_tw\/wp-json\/wp\/v2\/tags?post=4630"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}