{"id":1272,"date":"2026-04-17T17:28:00","date_gmt":"2026-04-17T09:28:00","guid":{"rendered":"https:\/\/yunyanglib.cn\/?p=1272"},"modified":"2026-04-17T17:28:02","modified_gmt":"2026-04-17T09:28:02","slug":"%e3%80%90java%e3%80%91%e6%b7%b1%e5%85%a5%e6%8b%86%e8%a7%a3-instanceof-%e5%85%b3%e9%94%ae%e5%ad%97%ef%bc%9a%e7%94%a8%e6%b3%95%e3%80%81%e5%9c%ba%e6%99%af%e4%b8%8e%e9%81%bf%e5%9d%91%e6%8c%87%e5%8d%97","status":"publish","type":"post","link":"https:\/\/yunyanglib.cn\/?p=1272","title":{"rendered":"\u3010Java\u3011\u6df1\u5165\u62c6\u89e3 instanceof \u5173\u952e\u5b57\uff1a\u7528\u6cd5\u3001\u573a\u666f\u4e0e\u907f\u5751\u6307\u5357"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u5927\u5bb6\u597d\uff0c\u6211\u662f\u4e91\u626c\uff5e \u4eca\u5929\u6765\u548c\u5927\u5bb6\u804a\u804a Java \u4e2d\u4e00\u4e2a\u57fa\u7840\u4f46\u9ad8\u9891\u4f7f\u7528\u7684\u5173\u952e\u5b57 \u2014\u2014instanceof\u3002\u4f5c\u4e3a\u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u91cc\u7684 \u201c\u7c7b\u578b\u68c0\u6d4b\u5668\u201d\uff0c\u5b83\u770b\u4f3c\u7b80\u5355\uff0c\u5374\u5728\u7c7b\u578b\u5224\u65ad\u3001\u907f\u514d\u8f6c\u578b\u5f02\u5e38\u7b49\u573a\u666f\u4e2d\u53d1\u6325\u7740\u5173\u952e\u4f5c\u7528\u3002\u8fd9\u7bc7\u6587\u7ae0\u4f1a\u4ece\u6838\u5fc3\u7528\u6cd5\u3001\u5b9e\u6218\u793a\u4f8b\u3001\u7ee7\u627f\u7279\u6027\u5230\u7279\u6b8a\u60c5\u51b5\uff0c\u5e2e\u5927\u5bb6\u5f7b\u5e95\u5403\u900f\u8fd9\u4e2a\u5173\u952e\u5b57\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e00\u3001instanceof \u6838\u5fc3\u4f5c\u7528\uff1a\u5224\u65ad\u5bf9\u8c61\u7684 \u201c\u771f\u5b9e\u8eab\u4efd\u201d<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728 Java \u5f00\u53d1\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u9047\u5230 \u201c\u4e0d\u786e\u5b9a\u67d0\u4e2a\u5bf9\u8c61\u662f\u5426\u5c5e\u4e8e\u67d0\u4e2a\u7c7b\u578b\u201d \u7684\u573a\u666f \u2014\u2014 \u6bd4\u5982\u53cd\u5e8f\u5217\u5316\u3001\u63a5\u6536\u5916\u90e8\u53c2\u6570\u65f6\u3002\u8fd9\u65f6\u5019 instanceof \u5c31\u6d3e\u4e0a\u7528\u573a\u4e86\uff1a\u5b83\u7528\u4e8e\u5224\u65ad\u4e00\u4e2a\u5bf9\u8c61\u662f\u5426\u7b26\u5408\u6307\u5b9a\u7684\u7c7b\u578b\uff08\u7c7b\u3001\u63a5\u53e3\u3001\u6570\u7ec4\u7b49\uff09\uff0c\u8fd4\u56de\u7ed3\u679c\u53ea\u6709 <code>true<\/code> \u6216 <code>false<\/code>\uff0c\u80fd\u5e2e\u6211\u4eec\u63d0\u524d\u89c4\u907f <code>ClassCastException<\/code> \u8f6c\u578b\u5f02\u5e38\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e8c\u3001\u57fa\u672c\u7528\u6cd5\uff1a\u8bed\u6cd5\u683c\u5f0f\u4e0e\u7b80\u5355\u793a\u4f8b<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">instanceof \u7684\u8bed\u6cd5\u975e\u5e38\u7b80\u6d01\uff0c\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u8bed\u6cd5\uff1a\u5bf9\u8c61 instanceof \u76ee\u6807\u7c7b\u578b\nobject instanceof TargetType\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>object<\/code>\uff1a\u8981\u5224\u65ad\u7684\u5bf9\u8c61\uff08\u4e0d\u80fd\u662f\u57fa\u672c\u6570\u636e\u7c7b\u578b\uff0c\u5426\u5219\u7f16\u8bd1\u62a5\u9519\uff09<\/li>\n\n\n\n<li><code>TargetType<\/code>\uff1a\u53ef\u4ee5\u662f\u7c7b\u3001\u63a5\u53e3\u3001\u6570\u7ec4\u7c7b\u578b\uff08\u5fc5\u987b\u662f\u5f15\u7528\u7c7b\u578b\uff09<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3e\u4e2a\u6700\u7b80\u5355\u7684\u4f8b\u5b50\uff0c\u5224\u65ad String \u5bf9\u8c61\u548c Integer \u5bf9\u8c61\u7684\u7c7b\u578b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class InstanceofDemo {\n    public static void main(String&#91;] args) {\n        Object str = \"\u4e91\u626c\u306eBlog\";\n        Object num = 100;\n        Object bool = true;\n\n        \/\/ \u5224\u65ad\u662f\u5426\u4e3a String \u7c7b\u578b\n        System.out.println(str instanceof String);  \/\/ true\n        \/\/ \u5224\u65ad\u662f\u5426\u4e3a Integer \u7c7b\u578b\n        System.out.println(num instanceof Integer); \/\/ true\n        \/\/ \u5224\u65ad bool \u662f\u5426\u4e3a String \u7c7b\u578b\n        System.out.println(bool instanceof String); \/\/ false\n        \/\/ \u5224\u65ad str \u662f\u5426\u4e3a Object \u7c7b\u578b\uff08\u6240\u6709\u7c7b\u90fd\u7ee7\u627f Object\uff09\n        System.out.println(str instanceof Object);  \/\/ true\n    }\n}\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd0\u884c\u7ed3\u679c\u4f1a\u4f9d\u6b21\u8f93\u51fa <code>true\u3001true\u3001false\u3001true<\/code>\uff0c\u5b8c\u5168\u7b26\u5408\u6211\u4eec\u7684\u9884\u671f\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e09\u3001\u5b9e\u6218\u573a\u666f\uff1a\u53cd\u5e8f\u5217\u5316\u4e2d\u7684\u7c7b\u578b\u6821\u9a8c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">instanceof \u6700\u5b9e\u7528\u7684\u573a\u666f\u4e4b\u4e00\u5c31\u662f<strong>\u53cd\u5e8f\u5217\u5316<\/strong>\u3002\u5f53\u6211\u4eec\u4ece\u6587\u4ef6\u3001\u7f51\u7edc\u4e2d\u8bfb\u53d6\u5bf9\u8c61\u65f6\uff0c\u65e0\u6cd5\u4fdd\u8bc1\u63a5\u6536\u5230\u7684\u5bf9\u8c61\u7c7b\u578b\u4e00\u5b9a\u7b26\u5408\u9884\u671f\uff0c\u5982\u679c\u76f4\u63a5\u5f3a\u5236\u8f6c\u578b\uff0c\u5f88\u53ef\u80fd\u629b\u51fa\u5f02\u5e38\u3002\u8fd9\u65f6\u5019\u7528 instanceof \u63d0\u524d\u5224\u65ad\uff0c\u5c31\u80fd\u5b89\u5168\u8f6c\u578b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6765\u770b\u4e00\u4e2a\u53cd\u5e8f\u5217\u5316\u7684\u5b9e\u6218\u793a\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>import java.io.*;\n\n\/\/ \u5b9a\u4e49\u4e00\u4e2a\u5b9e\u4f53\u7c7b\nclass User implements Serializable {\n    private String username;\n    private int age;\n\n    \/\/ \u6784\u9020\u65b9\u6cd5\u3001getter\/setter \u7701\u7565\n}\n\npublic class SerializeDemo {\n    public static void main(String&#91;] args) throws IOException, ClassNotFoundException {\n        \/\/ 1. \u5e8f\u5217\u5316 User \u5bf9\u8c61\u5230\u6587\u4ef6\n        User originalUser = new User(\"YunYang\", 25);\n        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(\"user.dat\"));\n        oos.writeObject(originalUser);\n        oos.close();\n\n        \/\/ 2. \u53cd\u5e8f\u5217\u5316\u8bfb\u53d6\u5bf9\u8c61\n        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(\"user.dat\"));\n        Object obj = ois.readObject();\n        ois.close();\n\n        \/\/ 3. \u7528 instanceof \u5224\u65ad\u7c7b\u578b\uff0c\u5b89\u5168\u8f6c\u578b\n        if (obj instanceof User) {\n            User user = (User) obj; \/\/ \u5b89\u5168\u8f6c\u578b\n            System.out.println(\"\u7528\u6237\u540d\uff1a\" + user.getUsername());\n            System.out.println(\"\u5e74\u9f84\uff1a\" + user.getAge());\n        } else {\n            System.out.println(\"\u53cd\u5e8f\u5217\u5316\u5f97\u5230\u7684\u5bf9\u8c61\u4e0d\u662f User \u7c7b\u578b\uff0c\u65e0\u6cd5\u8f6c\u578b\");\n        }\n    }\n}\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679c\u53cd\u5e8f\u5217\u5316\u5f97\u5230\u7684\u662f User \u7c7b\u578b\uff0c\u5c31\u4f1a\u6b63\u5e38\u8f93\u51fa\u4fe1\u606f\uff1b\u5982\u679c\u6587\u4ef6\u88ab\u7be1\u6539\uff0c\u5f97\u5230\u7684\u662f\u5176\u4ed6\u7c7b\u578b\u5bf9\u8c61\uff0c\u4f1a\u8fdb\u5165 else \u5206\u652f\uff0c\u907f\u514d\u629b\u51fa\u8f6c\u578b\u5f02\u5e38\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u56db\u3001\u7ee7\u627f\u5173\u7cfb\u4e0b\u7684 instanceof\uff1a\u5b50\u7c7b\u5bf9\u8c61\u662f \u201c\u7236\u7c7b\u7c7b\u578b\u201d \u5417\uff1f<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java \u662f\u9762\u5411\u5bf9\u8c61\u8bed\u8a00\uff0c\u6240\u6709\u7c7b\u90fd\u9690\u5f0f\u7ee7\u627f Object \u7c7b\uff0c\u800c\u5b50\u7c7b\u548c\u7236\u7c7b\u4e4b\u95f4\u4e5f\u5b58\u5728\u7ee7\u627f\u5173\u7cfb\u3002\u8fd9\u65f6\u5019 instanceof \u7684\u5224\u65ad\u89c4\u5219\u662f\uff1a<strong>\u5b50\u7c7b\u5bf9\u8c61 instanceof \u7236\u7c7b\u7c7b\u578b \u2192 \u8fd4\u56de true<\/strong>\uff0c\u7236\u7c7b\u5bf9\u8c61 instanceof \u5b50\u7c7b\u7c7b\u578b \u2192 \u8fd4\u56de false\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3e\u4e2a\u7ee7\u627f\u7684\u4f8b\u5b50\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u7236\u7c7b\nclass Animal {}\n\/\/ \u5b50\u7c7b\nclass Dog extends Animal {}\n\/\/ \u53e6\u4e00\u4e2a\u5b50\u7c7b\nclass Cat extends Animal {}\n\npublic class InheritDemo {\n    public static void main(String&#91;] args) {\n        Animal animal = new Animal();\n        Dog dog = new Dog();\n        Animal dogAsAnimal = new Dog(); \/\/ \u7236\u7c7b\u5f15\u7528\u6307\u5411\u5b50\u7c7b\u5bf9\u8c61\n\n        System.out.println(dog instanceof Animal);      \/\/ true\uff08\u5b50\u7c7b\u662f\u7236\u7c7b\u7c7b\u578b\uff09\n        System.out.println(animal instanceof Dog);      \/\/ false\uff08\u7236\u7c7b\u4e0d\u662f\u5b50\u7c7b\u7c7b\u578b\uff09\n        System.out.println(dogAsAnimal instanceof Dog); \/\/ true\uff08\u7236\u7c7b\u5f15\u7528\u6307\u5411\u5b50\u7c7b\uff0c\u672c\u8d28\u662f\u5b50\u7c7b\u5bf9\u8c61\uff09\n        System.out.println(dog instanceof Cat);         \/\/ \u7f16\u8bd1\u62a5\u9519\uff08\u7c7b\u578b\u4e0d\u517c\u5bb9\uff09\n    }\n}\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u89c4\u5219\u5f88\u91cd\u8981\uff0c\u6bd4\u5982\u5728\u96c6\u5408\u64cd\u4f5c\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u7528\u7236\u7c7b\u5f15\u7528\u63a5\u6536\u5b50\u7c7b\u5bf9\u8c61\uff0c\u8fd9\u65f6\u5019\u7528 instanceof \u5c31\u80fd\u5224\u65ad\u5176\u771f\u5b9e\u7c7b\u578b\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e94\u3001\u7279\u6b8a\u60c5\u51b5\uff1anull \u4e0e instanceof<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u540e\u8981\u6ce8\u610f\u4e00\u4e2a\u7279\u6b8a\u573a\u666f\uff1a<code>null<\/code> \u4e0e instanceof \u7684\u7ed3\u5408\u3002\u56e0\u4e3a null \u8868\u793a \u201c\u6ca1\u6709\u6307\u5411\u4efb\u4f55\u5bf9\u8c61\u201d\uff0c\u6240\u4ee5\u5b83\u4e0d\u5c5e\u4e8e\u4efb\u4f55\u7c7b\u7684\u5b9e\u4f8b \u2014\u2014<strong>\u4efb\u4f55\u60c5\u51b5\u4e0b\uff0cnull instanceof \u4efb\u610f\u7c7b\u578b \u2192 \u90fd\u8fd4\u56de false<\/strong>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u793a\u4f8b\u9a8c\u8bc1\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class NullDemo {\n    public static void main(String&#91;] args) {\n        String str = null;\n        Integer num = null;\n        Object obj = null;\n\n        System.out.println(str instanceof String);  \/\/ false\n        System.out.println(num instanceof Integer); \/\/ false\n        System.out.println(obj instanceof Object);  \/\/ false\n    }\n}\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u7279\u6027\u53ef\u4ee5\u5e2e\u6211\u4eec\u5904\u7406 \u201c\u5bf9\u8c61\u53ef\u80fd\u4e3a null\u201d \u7684\u573a\u666f\uff0c\u6bd4\u5982\u5148\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u4e3a null\uff0c\u518d\u7528 instanceof \u5224\u65ad\u7c7b\u578b\uff0c\u907f\u514d\u7a7a\u6307\u9488\u5f02\u5e38\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u603b\u7ed3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">instanceof \u867d\u7136\u662f Java \u57fa\u7840\u5173\u952e\u5b57\uff0c\u4f46\u5728\u7c7b\u578b\u6821\u9a8c\u3001\u5b89\u5168\u8f6c\u578b\u7b49\u573a\u666f\u4e2d\u4e0d\u53ef\u6216\u7f3a\u3002\u6838\u5fc3\u8981\u70b9\u603b\u7ed3\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u4f5c\u7528\uff1a\u5224\u65ad\u5bf9\u8c61\u662f\u5426\u7b26\u5408\u6307\u5b9a\u5f15\u7528\u7c7b\u578b\uff0c\u8fd4\u56de boolean\uff1b<\/li>\n\n\n\n<li>\u8bed\u6cd5\uff1a<code>object instanceof TargetType<\/code>\uff0cobject \u4e0d\u80fd\u662f\u57fa\u672c\u7c7b\u578b\uff1b<\/li>\n\n\n\n<li>\u7ee7\u627f\u573a\u666f\uff1a\u5b50\u7c7b\u5bf9\u8c61 instanceof \u7236\u7c7b \u2192 true\uff0c\u53cd\u4e4b\u5219 false\uff1b<\/li>\n\n\n\n<li>null \u573a\u666f\uff1anull instanceof \u4efb\u610f\u7c7b\u578b \u2192 false\uff1b<\/li>\n\n\n\n<li>\u6838\u5fc3\u7528\u9014\uff1a\u53cd\u5e8f\u5217\u5316\u3001\u96c6\u5408\u5143\u7d20\u7c7b\u578b\u5224\u65ad\u3001\u907f\u514d\u8f6c\u578b\u5f02\u5e38\u3002<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679c\u5927\u5bb6\u5728\u4f7f\u7528 instanceof \u65f6\u9047\u5230\u8fc7\u7279\u6b8a\u573a\u666f\uff0c\u6216\u8005\u6709\u5176\u4ed6\u7591\u95ee\uff0c\u6b22\u8fce\u5728\u8bc4\u8bba\u533a\u4ea4\u6d41\uff5e \u540e\u7eed\u6211\u8fd8\u4f1a\u5206\u4eab\u66f4\u591a Java \u57fa\u7840\u8fdb\u9636\u77e5\u8bc6\u70b9\uff0c\u8bb0\u5f97\u5173\u6ce8\u54e6\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5927\u5bb6\u597d\uff0c\u6211\u662f\u4e91\u626c\uff5e \u4eca\u5929\u6765\u548c\u5927\u5bb6\u804a\u804a Java \u4e2d\u4e00\u4e2a\u57fa\u7840\u4f46\u9ad8\u9891\u4f7f\u7528\u7684\u5173\u952e\u5b57 \u2014\u2014instanceof\u3002\u4f5c\u4e3a\u9762<\/p>\n<div class=\"more-link\">\n\t\t\t\t <a href=\"https:\/\/yunyanglib.cn\/?p=1272\" class=\"link-btn theme-btn\"><span>Read More <\/span> <i class=\"fa fa-caret-right\"><\/i><\/a>\n\t\t\t<\/div>\n","protected":false},"author":1,"featured_media":1275,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[15],"class_list":["post-1272","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-java"],"_links":{"self":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1272","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1272"}],"version-history":[{"count":2,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1272\/revisions"}],"predecessor-version":[{"id":1274,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1272\/revisions\/1274"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/media\/1275"}],"wp:attachment":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1272"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1272"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}