关于Java中子类调用父类方法

class A {
    int x = 6;
    private int y = 2;

    public A(int a) {
        x = a;
    }
    int getz() {
        int z;
        z = x / y;
        return z;
    }
    void show() {
        System.out.println("x=" + x);
        System.out.println("y=" + y);
        System.out.println("z=" + getz());
    }
}

class B extends A {
    int x = 3, y = 5, z;
    public B(int a) {
        super(a);
    }
    int getz() {
        z = x + y;
        return z;
    }
}

public class Temp {
    public static void main(String[] args) {
        A num1 = new A(10);
        B num2 = new B(9);
        num1.show();
        num2.show();
    }
}