{"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\/blog\/java\/java-instanceof","title":{"rendered":"Java \u5909\u6570\u306e\u578b\u3092 instanceof \u3067\u78ba\u8a8d\u3059\u308b"},"content":{"rendered":"

\u68c0\u67e5\u53d8\u91cf\u7c7b\u578b\u3002<\/h2>\n\n\n\n

\u672c\u793a\u4f8b\u7a0b\u5e8f\u6f14\u793a\u4e86\u5982\u4f55\u5728 Java \u4e2d\u68c0\u67e5\u53d8\u91cf\u7684\u7c7b\u578b\u3002<\/p>\n\n\n\n

Java \u662f\u4e00\u79cd\u9759\u6001\u7c7b\u578b\u8bed\u8a00\uff0c\u7c7b\u578b\u662f\u663e\u5f0f\u58f0\u660e\u7684\uff0c\u56e0\u6b64\u5f88\u5c11\u9700\u8981\u68c0\u67e5\u7c7b\u578b\u3002\u4f46\u662f\uff0c\u5728\u4f7f\u7528\u7ee7\u627f\u5bf9\u8c61\u65f6\uff0c\u7c7b\u578b\u68c0\u67e5\u5c31\u53d8\u5f97\u5fc5\u8981\u4e86\u3002<\/p>\n\n\n\n

\u5982\u4f55\u5728 Java \u4e2d\u68c0\u67e5\u7c7b\u578b instanceof<\/strong> \u60a8\u53ef\u4ee5\u4f7f\u7528\u8fd0\u7b97\u7b26\uff0c\u901a\u8fc7 if \u8bed\u53e5\u6765\u8bc4\u4f30\u7c7b\u548c\u63a5\u53e3\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n\n\n\n

\n

\u591a\u53d8\u7684<\/em> instanceof \u30af\u30e9\u30b9<\/p>\n\n\n\n

\u591a\u53d8\u7684<\/em> instanceof \u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9<\/p>\n<\/div><\/div>\n\n\n\n

instanceof<\/strong> \u60a8\u53ef\u4ee5\u5728\u53f3\u4fa7\u6307\u5b9a\u7c7b\u540d\u6216\u63a5\u53e3\u540d\u3002instanceof<\/strong> \u8fd4\u56de\u503c\u662f\u4e00\u4e2a\u5e03\u5c14\u503c\uff0c\u5982\u679c\u4e3a\u771f\uff0c\u5219\u8be5\u53d8\u91cf\u4e3a\u6307\u5b9a\u7684\u7c7b\u6216\u63a5\u53e3\u3002<\/p>\n\n\n\n

\n

\u804a\u5929\u548c\u5373\u65f6\u901a\u8baf<\/a> \u8fd9\u662f\u4e00\u6b3e\u7528\u6237\u53cb\u597d\u3001\u96c6\u6210\u5ea6\u9ad8\u7684\u7fa4\u4ef6\uff0c\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\u548c\u8003\u52e4\u7ba1\u7406\u4e8e\u4e00\u4f53\uff0c\u5e76\u4e3a\u4f01\u4e1a\u63d0\u4f9b\u5f3a\u5927\u7684\u5b89\u5168\u4fdd\u969c\u3002\u514d\u8d39\u4f7f\u7528\uff01<\/mark><\/p>\n<\/a>\n<\/div>\n\n\n\n

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

\u6211\u4eec\u5148\u4ece\u6700\u7b80\u5355\u7684\u6a21\u5f0f\u5f00\u59cb\u3002\u5982\u679c\u53d8\u91cf i \u662f\u4e00\u4e2a\u6574\u6570\uff0c\u5219\u8fd4\u56de true\uff1b\u5426\u5219\uff0c\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\u7ed3\u679c<\/h4>\n\n\n\n
true<\/code><\/pre><\/div>\n\n\n\n
\u5909\u6570 i \u306f Integer \u306a\u306e\u3067\u3001\u7d50\u679c\u306f true \u306b\u306a\u308a\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u3053\u308c\u3067\u306f\u5f53\u305f\u308a\u524d\u3059\u304e\u3066 instanceof \u304c\u306a\u3093\u306e\u305f\u3081\u306b\u3042\u308b\u304b\u5206\u304b\u306a\u3044\u306e\u3067\u3001\u3082\u3046\u5c11\u3057\u8907\u96d1\u306b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n
instanceof \u306e\u52b9\u679c\u7684\u306a\u4f7f\u3044\u65b9<\/h2>\n\n\n\n
instanceof \u306e\u52b9\u679c\u7684\u306a\u4f7f\u3044\u65b9\u306e\u4e00\u3064\u306b\u3001\u305d\u306e\u5909\u6570\u304c\u3069\u306e\u5b50\u30af\u30e9\u30b9\u306a\u306e\u304b\u3092\u5224\u5b9a\u3059\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801<\/h4>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3a Animal \u7684\u52a8\u7269\u7c7b\uff0c\u4ee5\u53ca\u4e24\u4e2a\u7ee7\u627f\u81ea Animal \u7c7b\u7684\u7c7b Dog \u548c Cat\u3002\u521b\u5efa\u5b9e\u4f8b\u540e\uff0c\u4f7f\u7528 `play` \u65b9\u6cd5\u5b9a\u4e49\u53d8\u91cf\u3002 instanceof<\/strong> \u7cfb\u7edf\u4f1a\u5224\u65ad\u8fd9\u4e00\u70b9\uff0c\u5e76\u636e\u6b64\u5bf9\u63a7\u5236\u53f0\u8f93\u51fa\u8fdb\u884c\u5206\u652f\u5904\u7406\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\u7ed3\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
\u5173\u952e\u5728\u4e8e\uff0c\u5728\u201cplay\u201d\u65b9\u6cd5\u4e2d\uff0c\u65e0\u6cd5\u77e5\u9053\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u7684\u201canimal\u201d\u662f\u72d7\u8fd8\u662f\u732b\u3002<\/p>\n\n\n\n
instanceof<\/strong> \u56e0\u6b64\uff0c\u7531\u4e8e\u6211\u4eec\u8fd8\u53ef\u4ee5\u68c0\u67e5\u8d85\u7c7b\uff08\u52a8\u7269\uff09\u4e2d\u5305\u542b\u7684\u5b50\u7c7b\uff08\u72d7\u6216\u732b\uff09\u7684\u5b9e\u4f8b\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u7528\u8fd9\u79cd\u65b9\u5f0f\u4f7f\u7528\u5b83\u3002<\/p>\n\n\n\n
\u68c0\u67e5\u7279\u5b9a\u63a5\u53e3\u662f\u5426\u5df2\u5b9e\u73b0\u3002<\/h2>\n\n\n\n
instanceof \u306e\u5bfe\u8c61\u3068\u306a\u308b\u5909\u6570\u306b\u3001\u3042\u308b\u7279\u5b9a\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u304c\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308b\u304b\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\u3053\u306e\u3088\u3046\u306a\u4f7f\u3044\u65b9\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801<\/h4>\n\n\n\n
\u6b21\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u3067\u306f\u3001\u4f50\u85e4\u3055\u3093\u3001\u9234\u6728\u3055\u3093\u30af\u30e9\u30b9\u3092\u4f5c\u6210\u3057\u3001\u9234\u6728\u3055\u3093\u3060\u3051\u304c\u8eca\u3092\u6301\u3063\u3066\u3044\u308b\u60f3\u5b9a\u3067\u3001\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9 Car \u3092 implements \u3057\u3066\u3044\u307e\u3059\u3002goShopping() \u30e1\u30bd\u30c3\u30c9\u306f\u8cb7\u3044\u7269\u306b\u884c\u304f\u51e6\u7406\u3092\u4eee\u5b9a\u3057\u3066\u3044\u307e\u3059\u304c\u3001Car \u3092 implements \u3057\u3066\u3044\u308b\u304b\u3001instanceof \u3067\u5224\u5b9a\u3057\u3066\u30b3\u30f3\u30bd\u30fc\u30eb\u51fa\u529b\u3092\u5206\u5c90\u3057\u3066\u3044\u307e\u3059\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
\u4f60\u53ef\u4ee5\u770b\u5230\uff0c\u5904\u7406\u5206\u652f\u53d6\u51b3\u4e8e Car \u662f\u5426\u5df2\u5b9e\u73b0\u3002<\/p>","protected":false},"excerpt":{"rendered":"
\u5909\u6570\u306e\u578b\u3092\u78ba\u8a8d\u3059\u308b Java \u3067\u5909\u6570\u306e\u578b\u3092\u78ba\u8a8d\u3059\u308b\u30b5\u30f3\u30d7\u30eb\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002 Java \u306f\u578b\u3092\u660e\u793a\u7684\u306b\u5ba3 […]<\/p>\n","protected":false},"author":1,"featured_media":9054,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"swell_btn_cv_data":"","footnotes":""},"categories":[19],"tags":[],"class_list":["post-4630","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/chat-messenger.com\/zh\/wp-json\/wp\/v2\/posts\/4630","targetHints":{"allow":["GET"]}}],"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}]}}