例子1:
class A {
public String show(D obj) {
return ("A and D");
}
public String show(A obj) {
return ("A and A");
}
}
class B extends A{
public String show(B obj){
return ("B and B");
}
public String show(A obj){
return ("B and A");
}
}
class C extends B{
}
class D extends B{
}
public class Demo {
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));
}
}
//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
例子2:
class X {
public void show(Y y){
System.out.println("x and y");
}
public void show(){
System.out.println("only x");
}
}
class Y extends X {
public void show(Y y){
System.out.println("y and y");
}
public void show(int i){
}
}
class main{
public static void main(String[] args) {
X x = new Y();
x.show(new Y());
x.show();
}
}
//结果
//y and y
//only x
第二个例子的结果是y and y,为什么第一个例子的第4行打印结果不是“B and B”而是B类里的show(A obj)里的结果?