{"id":268,"date":"2026-07-18T11:12:18","date_gmt":"2026-07-18T03:12:18","guid":{"rendered":"http:\/\/ssjava.xyz\/index.php\/2026\/07\/19\/%e5%a4%9a%e6%80%81%e7%9a%84%e6%9c%ac%e8%b4%a8%ef%bc%9a%e5%8a%a8%e6%80%81%e7%bb%91%e5%ae%9a%e3%80%81%e5%90%91%e4%b8%8a%e8%bd%ac%e5%9e%8b%e4%b8%8e%e5%90%91%e4%b8%8b%e8%bd%ac%e5%9e%8b\/"},"modified":"2026-07-19T11:30:26","modified_gmt":"2026-07-19T03:30:26","slug":"18-%e5%a4%9a%e6%80%81%e7%9a%84%e6%9c%ac%e8%b4%a8%ef%bc%9a%e5%8a%a8%e6%80%81%e7%bb%91%e5%ae%9a%e3%80%81%e5%90%91%e4%b8%8a%e8%bd%ac%e5%9e%8b%e4%b8%8e%e5%90%91%e4%b8%8b%e8%bd%ac%e5%9e%8b","status":"publish","type":"post","link":"https:\/\/ssjava.xyz\/index.php\/2026\/07\/18\/18-%e5%a4%9a%e6%80%81%e7%9a%84%e6%9c%ac%e8%b4%a8%ef%bc%9a%e5%8a%a8%e6%80%81%e7%bb%91%e5%ae%9a%e3%80%81%e5%90%91%e4%b8%8a%e8%bd%ac%e5%9e%8b%e4%b8%8e%e5%90%91%e4%b8%8b%e8%bd%ac%e5%9e%8b\/","title":{"rendered":"18. \u591a\u6001\u7684\u672c\u8d28\uff1a\u52a8\u6001\u7ed1\u5b9a\u3001\u5411\u4e0a\u8f6c\u578b\u4e0e\u5411\u4e0b\u8f6c\u578b"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u62bd\u8c61\u7c7b\u5b66\u5b8c\u4e86\uff0c\u4f60\u73b0\u5728\u5e94\u8be5\u77e5\u9053 \u300c\u7236\u7c7b\u53ea\u58f0\u660e\u3001\u5b50\u7c7b\u53bb\u5b9e\u73b0\u300d \u662f\u4e00\u79cd\u4ec0\u4e48\u611f\u89c9\u4e86\u3002\u90a3\u4e48\u7ee7\u7eed\u60f3\u4e00\u4e2a\u95ee\u9898\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5047\u5982\u4f60\u5199\u4e86\u4e00\u4e2a\u65b9\u6cd5\uff0c\u53c2\u6570\u7c7b\u578b\u662f\u67d0\u4e2a\u7236\u7c7b\u2014\u2014\u6bd4\u5982 <code>Animal animal<\/code>\u2014\u2014\u7136\u540e\u4f60\u4f20\u5165 <code>Dog<\/code>\u3001<code>Cat<\/code>\u3001<code>Bird<\/code> \u4e09\u4e2a\u4e0d\u540c\u7684\u5b50\u7c7b\u5bf9\u8c61\u3002\u8fd9\u4e2a\u65b9\u6cd5\u8c03\u7528 <code>animal.makeSound()<\/code>\uff0c\u7ed3\u679c\u4f1a\u600e\u6837\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u72d7\u6c6a\u6c6a\u53eb\u3001\u732b\u55b5\u55b5\u53eb\u3001\u9e1f\u53fd\u53fd\u53eb\u3002<\/strong> \u540c\u4e00\u4e2a\u65b9\u6cd5\u7b7e\u540d\uff0c\u4f20\u4e0d\u540c\u7684\u5bf9\u8c61\uff0c\u8868\u73b0\u51fa\u4e0d\u540c\u7684\u884c\u4e3a\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u5c31\u662f <strong>\u591a\u6001<\/strong>\uff08Polymorphism\uff09\u2014\u2014\u9762\u5411\u5bf9\u8c61\u4e09\u5927\u7279\u6027\u4e2d\u7684\u6700\u540e\u4e00\u5f20\u62fc\u56fe\u3002\u5b83\u7684\u5b57\u9762\u610f\u601d\u662f\u300c\u591a\u79cd\u5f62\u6001\u300d\uff1a\u540c\u4e00\u4e2a\u884c\u4e3a\uff0c\u5728\u4e0d\u540c\u5bf9\u8c61\u4e0a\u6709\u4e0d\u540c\u7684\u8868\u73b0\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u5c01\u88c5\u5173\u6ce8\u300c\u80fd\u4e0d\u80fd\u770b\u5230\u300d\uff0c\u7ee7\u627f\u5173\u6ce8\u300c\u80fd\u4e0d\u80fd\u590d\u7528\u300d\uff0c\u591a\u6001\u5173\u6ce8\u300c\u80fd\u4e0d\u80fd\u7075\u6d3b\u66ff\u6362\u300d\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e00\u3001\u591a\u6001\u7684\u5e95\u5c42\u57fa\u77f3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728\u62c6\u89e3\u591a\u6001\u7684\u8bed\u6cd5\u4e4b\u524d\uff0c\u6211\u4eec\u5fc5\u987b\u5148\u641e\u6e05\u695a\u4e00\u4ef6\u4e8b\uff1aJava \u662f\u600e\u4e48\u51b3\u5b9a\u300c\u8c03\u7528\u54ea\u4e2a\u65b9\u6cd5\u300d\u7684\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1.1 \u7f16\u8bd1\u65f6\u7c7b\u578b vs \u8fd0\u884c\u65f6\u7c7b\u578b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u770b\u4e00\u6bb5\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Animal a = new Dog();<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u91cc <code>a<\/code> \u6709\u4e24\u4e2a\u8eab\u4efd\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u7f16\u8bd1\u65f6\u7c7b\u578b<\/strong>\uff08\u58f0\u660e\u7c7b\u578b\uff09\uff1a<code>Animal<\/code>\u2014\u2014\u7f16\u8bd1\u5668\u53ea\u770b\u8fd9\u4e2a<\/li>\n\n\n<li><strong>\u8fd0\u884c\u65f6\u7c7b\u578b<\/strong>\uff08\u5b9e\u9645\u7c7b\u578b\uff09\uff1a<code>Dog<\/code>\u2014\u2014JVM \u8fd0\u884c\u65f6\u624d\u771f\u6b63\u77e5\u9053<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u591a\u6001\u7684\u7cbe\u9ad3\u5c31\u5728\u4e8e\uff1a<strong>\u7f16\u8bd1\u770b\u5de6\u8fb9\uff0c\u8fd0\u884c\u770b\u53f3\u8fb9\u3002<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7f16\u8bd1\u5668\u68c0\u67e5 <code>a<\/code> \u6709\u6ca1\u6709\u67d0\u4e2a\u65b9\u6cd5\uff0c\u53ea\u770b <code>Animal<\/code> \u7c7b\u91cc\u5b9a\u4e49\u4e86\u4ec0\u4e48\u3002\u4f46\u771f\u6b63\u8c03\u7528\u7684\u65f6\u5019\uff0cJVM \u770b\u7684\u662f <code>Dog<\/code> \u7c7b\u6709\u6ca1\u6709\u91cd\u5199\u8fd9\u4e2a\u65b9\u6cd5\u2014\u2014\u6709\u5c31\u8c03\u7528 <code>Dog<\/code> \u7684\uff0c\u6ca1\u6709\u624d\u5f80\u4e0a\u627e\u7236\u7c7b\u7684\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1.2 \u52a8\u6001\u7ed1\u5b9a\uff08Dynamic Binding\uff09<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0a\u9762\u8fd9\u4e2a\u300c\u7f16\u8bd1\u65f6\u4e0d\u77e5\u9053\u3001\u8fd0\u884c\u65f6\u624d\u51b3\u5b9a\u300d\u7684\u673a\u5236\uff0c\u5c31\u53eb <strong>\u52a8\u6001\u7ed1\u5b9a<\/strong>\uff0c\u4e5f\u53eb <strong>\u865a\u65b9\u6cd5\u8c03\u7528<\/strong>\uff08Virtual Method Invocation\uff09\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u65b9\u6cd5\u8c03\u7528\u7684\u7ed1\u5b9a\u6709\u4e24\u79cd\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>\u7ed1\u5b9a\u7c7b\u578b<\/th><th>\u4ec0\u4e48\u65f6\u5019\u51b3\u5b9a<\/th><th>\u9488\u5bf9\u4ec0\u4e48<\/th><\/tr><\/thead><tbody><tr><td>\u9759\u6001\u7ed1\u5b9a<\/td><td>\u7f16\u8bd1\u671f<\/td><td><code>static<\/code> \u65b9\u6cd5\u3001<code>private<\/code> \u65b9\u6cd5\u3001<code>final<\/code> \u65b9\u6cd5\u3001\u6784\u9020\u5668<\/td><\/tr><tr><td>\u52a8\u6001\u7ed1\u5b9a<\/td><td>\u8fd0\u884c\u671f<\/td><td>\u666e\u901a\u5b9e\u4f8b\u65b9\u6cd5\uff08\u975e static \/ private \/ final\uff09<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u9759\u6001\u7ed1\u5b9a\u7684\u65b9\u6cd5\u5728\u7f16\u8bd1\u65f6\u5c31\u786e\u5b9a\u4e86\u8c03\u7528\u76ee\u6807\u2014\u2014\u6bd4\u5982 <code>static<\/code> \u65b9\u6cd5\u8ddf\u7c7b\u7ed1\u5b9a\uff0c\u4e0d\u5b58\u5728\u591a\u6001\u884c\u4e3a\u3002<code>final<\/code> \u65b9\u6cd5\u4e0d\u80fd\u88ab\u91cd\u5199\uff0cJVM \u4e5f\u77e5\u9053\u53ef\u4ee5\u76f4\u63a5\u9501\u5b9a\u3002\u53ea\u6709\u90a3\u4e9b\u80fd\u88ab\u91cd\u5199\u7684\u666e\u901a\u65b9\u6cd5\uff0cJVM \u624d\u9700\u8981\u300c\u52a8\u6001\u7ed1\u5b9a\u300d\u2014\u2014\u8fd0\u884c\u65f6\u770b\u5bf9\u8c61\u7684\u5b9e\u9645\u7c7b\u578b\uff0c\u627e\u5230\u5bf9\u5e94\u7684\u65b9\u6cd5\u53bb\u6267\u884c\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1.3 \u4e00\u4e2a\u5c0f\u5b9e\u9a8c\u770b\u770b\u52a8\u6001\u7ed1\u5b9a\u600e\u4e48\u5de5\u4f5c<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>class Animal {\n    public void makeSound() {\n        System.out.println(\"\u52a8\u7269\u53d1\u51fa\u58f0\u97f3\");\n    }\n    public static void staticMethod() {\n        System.out.println(\"Animal \u7684\u9759\u6001\u65b9\u6cd5\");\n    }\n}\n\nclass Dog extends Animal {\n    @Override\n    public void makeSound() {\n        System.out.println(\"\u6c6a\u6c6a\u6c6a\uff01\");\n    }\n    public static void staticMethod() {\n        System.out.println(\"Dog \u7684\u9759\u6001\u65b9\u6cd5\");\n    }\n}\n\npublic class Test {\n    public static void main(String[] args) {\n        Animal a = new Dog();\n        a.makeSound();      \/\/ \u52a8\u6001\u7ed1\u5b9a \u2192 \u8f93\u51fa\uff1a\u6c6a\u6c6a\u6c6a\uff01\n        a.staticMethod();   \/\/ \u9759\u6001\u7ed1\u5b9a \u2192 \u8f93\u51fa\uff1aAnimal \u7684\u9759\u6001\u65b9\u6cd5\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u770b\u5230\u4e86\u5417\uff1f\u540c\u6837\u7684 <code>a.staticMethod()<\/code>\uff0c\u5982\u679c\u6309\u76f4\u89c9\u4ee5\u4e3a\u4e5f\u662f\u591a\u6001\uff0c\u90a3\u5c31\u8e29\u5751\u4e86\u2014\u2014\u9759\u6001\u65b9\u6cd5\u6ca1\u6709\u591a\u6001\u884c\u4e3a\uff0c\u8c03\u7528\u7684\u662f\u58f0\u660e\u7c7b\u578b\u7684\u7248\u672c\uff0c\u800c\u4e0d\u662f\u5b9e\u9645\u7c7b\u578b\u7684\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u53cd\u8fc7\u6765\u8bf4\uff0c\u666e\u901a\u65b9\u6cd5 <code>makeSound()<\/code> \u662f\u52a8\u6001\u7ed1\u5b9a\u7684\uff0c\u6240\u4ee5\u867d\u7136 <code>a<\/code> \u58f0\u660e\u4e3a <code>Animal<\/code> \u7c7b\u578b\uff0c\u4f46\u5b9e\u9645\u8c03\u7528\u7684\u662f <code>Dog<\/code> \u7684\u7248\u672c\u3002\u8fd9\u5c31\u662f\u591a\u6001\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e8c\u3001\u5411\u4e0a\u8f6c\u578b<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u591a\u6001\u7684\u524d\u63d0\u662f <strong>\u5411\u4e0a\u8f6c\u578b<\/strong>\uff08Upcasting\uff09\u2014\u2014\u628a\u5b50\u7c7b\u5bf9\u8c61\u8d4b\u503c\u7ed9\u7236\u7c7b\u5f15\u7528\u3002\u8fd9\u662f Java \u4e2d\u552f\u4e00\u4e00\u4e2a\u300c\u4e0d\u9700\u8981\u5f3a\u8f6c\u300d\u7684\u81ea\u52a8\u7c7b\u578b\u8f6c\u6362\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Dog dog = new Dog();\nAnimal animal = dog;               \/\/ \u5411\u4e0a\u8f6c\u578b\uff0c\u81ea\u52a8\u5b8c\u6210\nAnimal another = new Dog();        \/\/ \u5e38\u89c1\u5199\u6cd5\uff0c\u4e5f\u662f\u5411\u4e0a\u8f6c\u578b\n\n\/\/ \u7236\u7c7b\u5f15\u7528\u53ef\u4ee5\u8c03\u7528\u5b50\u7c7b\u7ee7\u627f\u6216\u91cd\u5199\u7684\u65b9\u6cd5\nanimal.makeSound();                \/\/ \u52a8\u6001\u7ed1\u5b9a \u2192 \u6c6a\u6c6a\u6c6a\uff01\nanimal.eat();                      \/\/ \u5b50\u7c7b\u7ee7\u627f\u7684\u65b9\u6cd5\u4e5f\u80fd\u8c03<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">2.1 \u5411\u4e0a\u8f6c\u578b\u7684\u7ea6\u675f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5411\u4e0a\u8f6c\u578b\u6709\u4e00\u4e2a <strong>\u9650\u5236<\/strong>\uff1a\u901a\u8fc7\u7236\u7c7b\u5f15\u7528\u53ea\u80fd\u8c03\u7528\u7236\u7c7b\u91cc\u5b9a\u4e49\u8fc7\u7684\u65b9\u6cd5\uff0c\u5b50\u7c7b\u65b0\u589e\u7684\u65b9\u6cd5\u662f\u770b\u4e0d\u5230\u7684\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Dog extends Animal {\n    public void wagTail() {\n        System.out.println(\"\u6447\u5c3e\u5df4\");\n    }\n}\n\nAnimal a = new Dog();\na.makeSound();     \/\/ \u2705 \u7236\u7c7b\u6709 makeSound()\uff0c\u53ef\u4ee5\u8c03\na.wagTail();       \/\/ \u274c \u7f16\u8bd1\u9519\u8bef\uff01Animal \u6ca1\u6709 wagTail() \u65b9\u6cd5<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u9650\u5236\u770b\u4f3c\u9ebb\u70e6\uff0c\u5176\u5b9e\u6070\u597d\u591a\u6001\u5b58\u5728\u7684\u610f\u4e49\u2014\u2014\u5982\u679c\u4f60\u53ef\u4ee5\u901a\u8fc7\u7236\u7c7b\u5f15\u7528\u8c03\u7528\u5b50\u7c7b\u65b0\u589e\u7684\u65b9\u6cd5\uff0c\u90a3\u591a\u6001\u5c31\u5931\u53bb\u4e86\u5b83\u7684\u8bbe\u8ba1\u4ef7\u503c\u3002\u591a\u6001\u60f3\u8981\u7684\u662f\u300c\u4e00\u5957\u7edf\u4e00\u7684 API \u8c03\u7528\u63a5\u53e3\u300d\uff0c\u800c\u4e0d\u662f\u300c\u6bcf\u4e2a\u5b50\u7c7b\u90fd\u6709\u81ea\u5df1\u7684\u4e00\u5806\u5947\u8469\u65b9\u6cd5\u300d\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e09\u3001\u5411\u4e0b\u8f6c\u578b\u4e0e instanceof<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5411\u4e0a\u8f6c\u578b\u662f\u81ea\u52a8\u7684\uff0c\u4f46\u6709\u65f6\u5019\u6211\u4eec\u9700\u8981\u53cd\u5411\u64cd\u4f5c\u2014\u2014\u628a\u7236\u7c7b\u5f15\u7528\u53d8\u56de\u5b50\u7c7b\u5f15\u7528\uff0c\u53bb\u8c03\u7528\u5b50\u7c7b\u7279\u6709\u7684\u65b9\u6cd5\u3002\u8fd9\u4e2a\u8fc7\u7a0b\u53eb <strong>\u5411\u4e0b\u8f6c\u578b<\/strong>\uff08Downcasting\uff09\uff0c\u9700\u8981 <strong>\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362<\/strong>\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Animal a = new Dog();\nDog dog = (Dog) a;           \/\/ \u5411\u4e0b\u8f6c\u578b\uff0c\u9700\u8981\u5f3a\u5236\u8f6c\u6362\ndog.wagTail();               \/\/ \u2705 \u73b0\u5728\u53ef\u4ee5\u8c03\u5b50\u7c7b\u7279\u6709\u7684\u65b9\u6cd5\u4e86<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">3.1 \u7c7b\u578b\u8f6c\u6362\u7684\u9519\u8bef\u2014\u2014ClassCastException<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5411\u4e0b\u8f6c\u578b\u662f\u6709\u98ce\u9669\u7684\u3002\u5982\u679c\u5f15\u7528\u7684\u771f\u5b9e\u7c7b\u578b\u4e0d\u662f\u76ee\u6807\u5b50\u7c7b\uff0c\u8fd0\u884c\u65f6\u4f1a\u629b\u51fa <code>ClassCastException<\/code>\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Animal a = new Cat();\nDog dog = (Dog) a;           \/\/ \u274c \u8fd0\u884c\u65f6\u5f02\u5e38\uff01Cat \u4e0d\u80fd\u8f6c\u4e3a Dog<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">3.2 \u5b89\u5168\u7684\u5411\u4e0b\u8f6c\u578b\uff1ainstanceof<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Java \u63d0\u4f9b\u4e86 <code>instanceof<\/code> \u5173\u952e\u5b57\u6765\u5224\u65ad\u4e00\u4e2a\u5bf9\u8c61\u7684\u771f\u5b9e\u7c7b\u578b\uff0c\u907f\u514d\u8f6c\u578b\u7206\u70b8\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>if (a instanceof Dog) {\n    Dog dog = (Dog) a;\n    dog.wagTail();\n} else if (a instanceof Cat) {\n    Cat cat = (Cat) a;\n    cat.climbTree();\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ece Java 14 \u5f00\u59cb\uff0c\u8fd8\u53ef\u4ee5\u7528 <code>instanceof<\/code> \u6a21\u5f0f\u5339\u914d\u7684\u8bed\u6cd5\uff0c\u628a\u7c7b\u578b\u5224\u65ad\u548c\u8f6c\u578b\u5199\u5728\u4e00\u8d77\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>if (a instanceof Dog dog) {\n    dog.wagTail();    \/\/ \u76f4\u63a5\u4f7f\u7528 dog \u53d8\u91cf\uff0c\u81ea\u52a8\u8f6c\u578b\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u5199\u6cd5\u66f4\u7b80\u6d01\uff0c\u63a8\u8350\u5728 JDK 14+ \u7684\u9879\u76ee\u91cc\u4f7f\u7528\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">3.3 \u4f7f\u7528\u5c0f\u5efa\u8bae<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u5411\u4e0a\u8f6c\u578b<\/strong>\uff1a\u653e\u5fc3\u7528\uff0c\u81ea\u52a8\u3001\u5b89\u5168\u3001\u662f\u65e5\u5e38\u5f00\u53d1\u7684\u4e3b\u8981\u64cd\u4f5c<\/li>\n\n\n<li><strong>\u5411\u4e0b\u8f6c\u578b<\/strong>\uff1a\u80fd\u5c11\u7528\u5c31\u5c11\u7528\u3002\u9891\u7e41\u5411\u4e0b\u8f6c\u578b\u8bf4\u660e\u4f60\u7684\u8bbe\u8ba1\u53ef\u80fd\u6709\u95ee\u9898\u2014\u2014\u591a\u6001\u7684\u76ee\u7684\u5c31\u662f\u907f\u514d\u5224\u65ad\u5177\u4f53\u7c7b\u578b<\/li>\n\n\n<li><strong>instanceof<\/strong>\uff1a\u5982\u679c\u4e00\u5b9a\u8981\u5411\u4e0b\u8f6c\u578b\uff0c\u52a1\u5fc5\u5148\u7528 instanceof \u68c0\u67e5<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">\u56db\u3001\u591a\u6001\u7684\u4e09\u5927\u4f53\u73b0\u5f62\u5f0f<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u591a\u6001\u4e0d\u53ea\u662f\u300c\u7236\u7c7b\u5f15\u7528\u6307\u5411\u5b50\u7c7b\u5bf9\u8c61\u300d\u8fd9\u4e00\u79cd\u5f62\u5f0f\u3002\u5728 Java \u4e2d\uff0c\u591a\u6001\u4f53\u73b0\u5728\u4e09\u4e2a\u65b9\u9762\uff1a<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4.1 \u7f16\u8bd1\u65f6\u591a\u6001\u2014\u2014\u65b9\u6cd5\u91cd\u8f7d\uff08Overload\uff09<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u65b9\u6cd5\u91cd\u8f7d\u662f\u6307\u540c\u4e00\u4e2a\u7c7b\u91cc\u6709\u591a\u4e2a\u540c\u540d\u65b9\u6cd5\uff0c\u53c2\u6570\u5217\u8868\u4e0d\u540c\u3002\u867d\u7136\u5b83\u4e5f\u53eb\u300c\u591a\u6001\u300d\uff0c\u4f46\u5b83\u5176\u5b9e\u662f <strong>\u7f16\u8bd1\u65f6\u591a\u6001<\/strong>\u2014\u2014\u7f16\u8bd1\u5668\u5728\u7f16\u8bd1\u65f6\u5c31\u786e\u5b9a\u4e86\u8c03\u7528\u54ea\u4e2a\u7248\u672c\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class Calculator {\n    public int add(int a, int b) {\n        return a + b;\n    }\n    public double add(double a, double b) {\n        return a + b;\n    }\n}\n\nCalculator calc = new Calculator();\ncalc.add(1, 2);       \/\/ \u7f16\u8bd1\u65f6\u5c31\u786e\u5b9a\u8c03\u7528 int \u7248\u672c\ncalc.add(1.0, 2.0);   \/\/ \u7f16\u8bd1\u65f6\u5c31\u786e\u5b9a\u8c03\u7528 double \u7248\u672c<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u65b9\u6cd5\u91cd\u8f7d\u7684\u300c\u591a\u6001\u300d\u53d1\u751f\u5728\u7f16\u8bd1\u671f\uff0c\u901a\u8fc7\u53c2\u6570\u7684\u9759\u6001\u7c7b\u578b\u6765\u51b3\u5b9a\u3002\u597d\u5904\u662f\u8ba9\u540c\u4e00\u4e2a\u65b9\u6cd5\u540d\u652f\u6301\u591a\u79cd\u53c2\u6570\uff0c\u4ee3\u7801\u66f4\u76f4\u89c2\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4.2 \u8fd0\u884c\u65f6\u591a\u6001\u2014\u2014\u65b9\u6cd5\u91cd\u5199\uff08Override\uff09<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u624d\u662f\u6211\u4eec\u901a\u5e38\u8bf4\u7684\u300c\u591a\u6001\u300d\u2014\u2014\u5b50\u7c7b\u91cd\u5199\u7236\u7c7b\u65b9\u6cd5\uff0cJVM \u5728\u8fd0\u884c\u671f\u901a\u8fc7\u52a8\u6001\u7ed1\u5b9a\u51b3\u5b9a\u8c03\u7528\u54ea\u4e2a\u7248\u672c\u3002\u8fd9\u662f\u9762\u5411\u5bf9\u8c61\u8bbe\u8ba1\u7684\u6838\u5fc3\u6b66\u5668\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4.3 \u53c2\u6570\u591a\u6001\u2014\u2014\u6cdb\u578b\uff08Generics\uff09<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e25\u683c\u6765\u8bf4\u6cdb\u578b\u4e0d\u7b97\u7ecf\u5178\u7684 OOP \u591a\u6001\uff0c\u4f46\u5e7f\u4e49\u4e0a\u5b83\u4e5f\u5c5e\u4e8e\u300c\u4e00\u4e2a\u63a5\u53e3\u9002\u914d\u591a\u79cd\u7c7b\u578b\u300d\u3002\u6cdb\u578b\u6211\u4eec\u4f1a\u5728\u96c6\u5408\u6846\u67b6\u4e0e\u6cdb\u578b\u90e8\u5206\u8be6\u7ec6\u8bb2\u89e3\uff0c\u8fd9\u91cc\u5148\u63d0\u4e2a\u540d\uff0c\u6709\u4e2a\u5370\u8c61\u5c31\u884c\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e94\u3001\u591a\u6001\u4e0e\u53d8\u91cf<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728 Java \u4e2d\uff0c<strong>\u65b9\u6cd5\u6709\u591a\u6001\uff0c\u4f46\u53d8\u91cf\u6ca1\u6709\u591a\u6001\u3002<\/strong> \u8fd9\u662f\u4e00\u4e2a\u5bb9\u6613\u8e29\u7684\u5751\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Parent {\n    public String name = \"\u7236\u7c7b\u53d8\u91cf\";\n    public void show() {\n        System.out.println(\"\u7236\u7c7b\u65b9\u6cd5\");\n    }\n}\n\nclass Child extends Parent {\n    public String name = \"\u5b50\u7c7b\u53d8\u91cf\";  \/\/ \u4e0d\u662f\u91cd\u5199\uff0c\u662f\u9690\u85cf\n    @Override\n    public void show() {\n        System.out.println(\"\u5b50\u7c7b\u65b9\u6cd5\");\n    }\n}\n\npublic class Test {\n    public static void main(String[] args) {\n        Parent p = new Child();\n        System.out.println(p.name);   \/\/ \u8f93\u51fa\uff1a\u7236\u7c7b\u53d8\u91cf\uff08\u53d8\u91cf\u6ca1\u6709\u591a\u6001\uff09\n        p.show();                     \/\/ \u8f93\u51fa\uff1a\u5b50\u7c7b\u65b9\u6cd5\uff08\u65b9\u6cd5\u6709\u591a\u6001\uff09\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u540c\u6837\u7528\u7236\u7c7b\u5f15\u7528\u6307\u5411\u5b50\u7c7b\u5bf9\u8c61\uff0c<strong>\u8bbf\u95ee\u53d8\u91cf\u770b\u58f0\u660e\u7c7b\u578b<\/strong>\uff08\u7f16\u8bd1\u65f6\u7c7b\u578b\uff09\uff0c<strong>\u8c03\u7528\u65b9\u6cd5\u770b\u5b9e\u9645\u7c7b\u578b<\/strong>\uff08\u8fd0\u884c\u65f6\u7c7b\u578b\uff0c\u52a8\u6001\u7ed1\u5b9a\u975e\u9759\u6001\/\u79c1\u6709\/final \u7684\u65b9\u6cd5\uff09\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6240\u4ee5\u5982\u679c\u4f60\u7684\u5b50\u7c7b\u548c\u7236\u7c7b\u6709\u540c\u540d\u5b57\u6bb5\uff0c<strong>\u6c38\u8fdc\u522b\u8fd9\u4e48\u505a<\/strong>\u3002\u8fd9\u4f1a\u8ba9\u4ee3\u7801\u7684\u8bfb\u8005\u4e00\u5934\u96fe\u6c34\uff0c\u89c9\u5f97\u4ee3\u7801\u50cf\u4e2a\u859b\u5b9a\u8c14\u7684\u732b\u2014\u2014\u770b\u8d77\u6765\u50cf\u662f\u7236\u7c7b\u7684\u503c\uff0c\u5b9e\u9645\u53c8\u50cf\u662f\u5b50\u7c7b\u7684\u503c\u3002\u5b57\u6bb5\u5e94\u8be5\u662f\u79c1\u6709\u7684\uff0c\u901a\u8fc7 getter\/setter \u8bbf\u95ee\uff0c\u5c31\u4e0d\u4f1a\u6709\u8fd9\u79cd\u95ee\u9898\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u516d\u3001\u591a\u6001\u4e2d\u9690\u85cf\u7684\u7ec6\u8282<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">6.1 private \u65b9\u6cd5\u6ca1\u6709\u591a\u6001<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5b50\u7c7b\u4e0d\u80fd\u91cd\u5199\u7236\u7c7b\u7684 <code>private<\/code> \u65b9\u6cd5\u3002\u5373\u4f7f\u4f60\u5728\u5b50\u7c7b\u91cc\u5199\u4e86\u4e00\u4e2a\u540c\u540d\u7684 private \u65b9\u6cd5\uff0c\u90a3\u4e5f\u662f\u5b50\u7c7b\u81ea\u5df1\u7684\u65b9\u6cd5\uff0c\u8ddf\u7236\u7c7b\u6ca1\u6709\u4efb\u4f55\u5173\u7cfb\u2014\u2014\u6ca1\u6709 override\uff0c\u53ea\u662f\u6070\u597d\u540c\u540d\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6.2 static \u65b9\u6cd5\u4e5f\u6ca1\u6709\u591a\u6001<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u524d\u9762\u5df2\u7ecf\u7528 <code>staticMethod()<\/code> \u6f14\u793a\u8fc7\u4e86\u3002\u9759\u6001\u65b9\u6cd5\u5c5e\u4e8e\u7c7b\uff0c\u4e0d\u5728\u5bf9\u8c61\u7684\u65b9\u6cd5\u8868\u91cc\uff0cJVM \u901a\u8fc7\u58f0\u660e\u7c7b\u578b\u76f4\u63a5\u8c03\u7528\uff0c\u4e0d\u5b58\u5728\u52a8\u6001\u7ed1\u5b9a\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6.3 final \u65b9\u6cd5\u4e0d\u80fd\u88ab\u91cd\u5199<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>final<\/code> \u65b9\u6cd5\u660e\u786e\u4e0d\u5141\u8bb8\u5b50\u7c7b\u91cd\u5199\uff0c\u6240\u4ee5\u4e5f\u4e0d\u5b58\u5728\u591a\u6001\u3002JVM \u53ef\u4ee5\u76f4\u63a5\u9759\u6001\u7ed1\u5b9a\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6.4 \u6784\u9020\u5668\u6ca1\u6709\u591a\u6001<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u6784\u9020\u5668\u4e0d\u80fd\u88ab\u7ee7\u627f\uff0c\u4e5f\u5c31\u4e0d\u5b58\u5728\u91cd\u5199\u3002\u7236\u7c7b\u548c\u5b50\u7c7b\u7684\u6784\u9020\u5668\u662f\u72ec\u7acb\u7684\uff0c\u53ea\u662f\u901a\u8fc7 <code>super()<\/code> \u5f62\u6210\u8c03\u7528\u94fe\u2014\u2014\u8fd9\u662f\u7ee7\u627f\u7684\u673a\u5236\uff0c\u4e0d\u662f\u591a\u6001\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e03\u3001\u603b\u7ed3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e00\u7bc7\u6211\u4eec\u8bb2\u4e86\u591a\u6001\u6700\u6838\u5fc3\u7684\u5e95\u5c42\u673a\u5236\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u591a\u6001\u7684\u672c\u8d28<\/strong>\uff1a\u540c\u4e00\u65b9\u6cd5\u7b7e\u540d\uff0c\u4e0d\u540c\u5bf9\u8c61\u4e0d\u540c\u884c\u4e3a<\/li>\n\n\n<li><strong>\u5e95\u5c42\u539f\u7406<\/strong>\uff1a\u7f16\u8bd1\u65f6\u7c7b\u578b vs \u8fd0\u884c\u65f6\u7c7b\u578b\u3001\u52a8\u6001\u7ed1\u5b9a\uff08\u865a\u65b9\u6cd5\u8c03\u7528\uff09<\/li>\n\n\n<li><strong>\u5411\u4e0a\u8f6c\u578b<\/strong>\uff1a\u5b50\u7c7b\u5bf9\u8c61\u2192\u7236\u7c7b\u5f15\u7528\uff0c\u81ea\u52a8\u5b89\u5168\uff0c\u4f46\u53ea\u80fd\u8c03\u7236\u7c7b\u6709\u7684\u65b9\u6cd5<\/li>\n\n\n<li><strong>\u5411\u4e0b\u8f6c\u578b\u4e0e instanceof<\/strong>\uff1a\u7236\u7c7b\u5f15\u7528\u2192\u5b50\u7c7b\u5f15\u7528\uff0c\u9700\u8981\u5f3a\u5236\u8f6c\u6362\uff0c\u5148\u7528 instanceof 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