java多态经典案例解析

如下代码会打印出什么？

public class A {
    public String show(D obj) {
        return ("A and D");
    }

    public String show(A obj) {
        return ("A and A");
    } 

}

public class B extends A{
    public String show(B obj){
        return ("B and B");
    }
    
    public String show(A obj){
        return ("B and A");
    } 
}

public class C extends B{

}

public class D extends B{

}

public class Test {
    public static void main(String[] args) {
        A a1 = new A();
        A a2 = new B();
        B b = new B();
        C c = new C();
        D d = new D();
        
        System.out.println("1--" + a1.show(b));
        System.out.println("2--" + a1.show(c));
        System.out.println("3--" + a1.show(d));
        System.out.println("4--" + a2.show(b));
        System.out.println("5--" + a2.show(c));
        System.out.println("6--" + a2.show(d));
        System.out.println("7--" + b.show(b));
        System.out.println("8--" + b.show(c));
        System.out.println("9--" + b.show(d));      
    }
}

运行结果

1--A and A
2--A and A
3--A and D
4--B and A
5--B and A
6--A and D
7--B and B
8--B and B
9--A and D

考点

继承链中方法调用的优先级来确认方法，该优先级为：this.show(O) > super.show(O) > this.show((super)O) > super.show((super)O)

参考文章
https://www.cnblogs.com/chenssy/p/3372798.html