成员函数与静态函数

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成员函数

编译看等号左边，运行看等号右边（即实际类型）

public class Demo {public static void main(String[] args) {fu f = new zi();System.out.println(f.num);//编译报错}}class fu {//int num = 3;}class zi extends fu {int num = 4;}

public class Demo {public static void main(String[] args) {zi f = new zi();System.out.println(f.num);// 输出是4}}class fu {int num = 3;}class zi extends fu {int num = 4;}

public class Demo {public static void main(String[] args) {zi f = new zi();System.out.println(f.num);//编译成功，输出是3；会因为extends去找基类。}}class fu {int num = 3;}class zi extends fu {// int num = 4;}

静态函数

编译和运行都看左边

因为是类变量

public class Demo {public static void main(String[] args) {fu f = new zi();System.out.println(f.num);// 编译报错，看的是fu类}}class fu {static int num = 3;}class zi extends fu {static int num = 4;}public class Demo {public static void main(String[] args) {fu f = new zi();System.out.println(f.num);// 输出的是fu类的3；}}class fu {static int num = 3;}class zi extends fu {static int num = 4;}public class Demo {public static void main(String[] args) {fu f = new zi();System.out.println(f.num);// 编译通过，输出的是fu类的3；}}class fu {static int num = 3;}class zi extends fu {static int num = 4;}

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