java 多态 回顾

public class App9 {

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

public String show(App9 obj) {
return "App and App";
}
}

class B extends App9 {

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

@Override
public String show(App9 obj) {
return "B and A";
}
}

class C extends B {

public String show(C obj) {
return "C AND C";
}

@Override
public String show(App9 obj) {
return "C AND A";
}
}

class D extends B {

@Override
public String show(D d) {
return "D AND D";
}

@Override
public String show(App9 a) {
return "A AND A";
}
}

public class App10 {

public static void main(String[] args) {
App9 a1 = new App9();
App9 a2 = new B();
B b = new B();
C c = new C();
D d = new D();
System.out.println(a1.show(b));// print App AND App
System.out.println(a1.show(c));// print App AND App
System.out.println(a1.show(d));// print APP AND D
System.out.println(a2.show(b));// print B AND A
System.out.println(a2.show(c));// print B AND A
System.out.println(a2.show(d));// print APP AND D
System.out.println(b.show(b));// print B AND B
System.out.println(b.show(c));// print B AND B
System.out.println(b.show(d));// print APP AND D
}
}