Java static关键字详解：实例讲解类变量、类方法和静态代码块

Java\u4e2d\u7684static\u5173\u952e\u8bcd\u7528\u4e8e\u6307\u5b9a\u7c7b\u53d8\u91cf\u548c\u7c7b\u65b9\u6cd5\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f8b\u5b50\uff0c\u7528\u4e8e\u751f\u52a8\u8be6\u7ec6\u8bf4\u660eJava\u4e2dstatic\u5173\u952e\u8bcd\u7684\u7528\u6cd5\uff1a\n\n1\u3001\u7c7b\u53d8\u91cf\u7684\u4f7f\u7528\uff1a\n\n\npublic class MyClass {\n static int count = 0;\n \n public MyClass() {\n count++;\n }\n \n public static void main(String[] args) {\n MyClass obj1 = new MyClass();\n MyClass obj2 = new MyClass();\n MyClass obj3 = new MyClass();\n \n System.out.println("Number of objects created: " + count); // \u8f93\u51fa\uff1aNumber of objects created: 3\n }\n}\n\n\n\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u7c7b\u53d8\u91cfcount\u88ab\u52a0\u4e0astatic\u8bf4\u660e\uff0c\u5b83\u88ab\u6240\u6709\u7c7b\u7684\u5bf9\u8c61\u6240\u5171\u4eab\u3002\u6bcf\u6b21\u521b\u5efaMyClass\u7684\u5bf9\u8c61\u65f6\uff0c\u6784\u9020\u51fd\u6570\u4f1a\u5c06count\u7684\u503c\u589e\u52a01\u3002\u901a\u8fc7\u5728main\u65b9\u6cd5\u4e2d\u8f93\u51facount\u7684\u503c\uff0c\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u5bf9\u8c61\u521b\u5efa\u7684\u6b21\u6570\u3002\n\n2\u3001\u7c7b\u65b9\u6cd5\u7684\u4f7f\u7528\uff1a\n\n\npublic class MathUtils {\n public static int add(int a, int b) {\n return a + b;\n }\n \n public static int multiply(int a, int b) {\n return a * b;\n }\n \n public static void main(String[] args) {\n int sum = MathUtils.add(5, 3);\n int product = MathUtils.multiply(2, 4);\n \n System.out.println("Sum: " + sum); // \u8f93\u51fa\uff1aSum: 8\n System.out.println("Product: " + product); // \u8f93\u51fa\uff1aProduct: 8\n }\n}\n\n\n\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0cMathUtils\u7c7b\u4e2d\u7684add\u548cmultiply\u65b9\u6cd5\u90fd\u88ab\u8bf4\u660e\u4e3astatic\u3002\u8fd9\u610f\u5473\u7740\u6211\u4eec\u53ef\u4ee5\u76f4\u63a5\u901a\u8fc7\u7c7b\u540d\u8c03\u7528\u8fd9\u4e9b\u65b9\u6cd5\uff0c\u800c\u4e0d\u9700\u8981\u521b\u5efaMathUtils\u7684\u5bf9\u8c61\u3002\n\n3\u3001\u9759\u6001\u4ee3\u7801\u5757\u7684\u4f7f\u7528\uff1a\n\n\npublic class StaticBlockExample {\n static {\n System.out.println("This is a static block.");\n }\n \n public static void main(String[] args) {\n System.out.println("Inside main method.");\n }\n}\n\n\n\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u9759\u6001\u4ee3\u7801\u5757\u5728\u7c7b\u52a0\u8f7d\u65f6\u6267\u884c\uff0c\u800c\u4e0d\u662f\u5728\u521b\u5efa\u5bf9\u8c61\u65f6\u6267\u884c\u3002\u5728main\u65b9\u6cd5\u4e2d\u8f93\u51fa\u7684\u5185\u5bb9\u4f1a\u5728\u9759\u6001\u4ee3\u7801\u5757\u8f93\u51fa\u4e4b\u540e\u3002\n\n\u603b\u7ed3\uff1a\n\n- static\u5173\u952e\u8bcd\u7528\u4e8e\u6307\u5b9a\u7c7b\u53d8\u91cf\u548c\u7c7b\u65b9\u6cd5\u3002\n\n- \u7c7b\u53d8\u91cf\u88ab\u6240\u6709\u7c7b\u7684\u5bf9\u8c61\u6240\u5171\u4eab\u3002\n\n- \u7c7b\u65b9\u6cd5\u53ef\u4ee5\u76f4\u63a5\u901a\u8fc7\u7c7b\u540d\u8c03\u7528\uff0c\u800c\u4e0d\u9700\u8981\u521b\u5efa\u5bf9\u8c61\u3002\n\n- \u9759\u6001\u4ee3\u7801\u5757\u5728\u7c7b\u52a0\u8f7d\u65f6\u6267\u884c\u3002