属性的继承

public class Test {
    
    
    public static void main(String[] args) {
    
    
        Son3 s = new Son3();
        System.out.println(s.val);// 100
    }
}
class Father3{
    
    
    int val = 0;
    public Father3(){
    
    
        this.val = 100;
    }
}
class Son3 extends Father3{
    
    
    public Son3(){
    
    
        super();
    }
}

public class Test_SS {
    
    
    public static void main(String[] args) {
    
    
        Father2 f = new Father2();
        // Son2 s = new Son2(); 结果与写在下面一样
        f.setVal(100);
        Son2 s = new Son2();
        System.out.println(f.getVal());// 100
        System.out.println(s.getVal());// 0
    }
}
class Father2{
    
    
    int val = 0;

    public void setVal(int val) {
    
    
        this.val = val;
    }

    public int getVal() {
    
    
        return val;
    }
}
class Son2 extends Father2{
    
    
}

由上面两个可以得知：子类继承的是父类属性的默认值，即在构造方法里面初始化的值，或者是直接给属性赋的值，比如属性：int val = 0;

另：Java 中如果继承了父类方法中的静态变量，那么多个子类操作的还是同一个静态变量

public class Test_SSSS {
    
    
    public static void main(String[] args) {
    
    
        Son4.val = 100;
        System.out.println(Father4.val);// 100
    }
}
class Father4{
    
    
    static int val = 0;

    public void setVal(int val) {
    
    
        this.val = val;
    }

    public int getVal() {
    
    
        return val;
    }
}
class Son4 extends Father4{
    
    
}