public class Polymorphism { 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(a1.show(b));
System.out.println(a1.show(c));
System.out.println(a1.show(d));
System.out.println(a2.show(b));
System.out.println(a2.show(c));
System.out.println(a2.show(d));
System.out.println(b.show(b));
System.out.println(b.show(c));
System.out.println(b.show(d));
}
}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{
}Exception in thread "main" java.lang.NoSuchMethodError: A.show(LA;)Ljava/lang/String;
at Polymorphism.main(Polymorphism.java:9)
类A已经被指定 为什么?
A a1 = new A();
A a2 = new B();
B b = new B();
C c = new C();
D d = new D();
System.out.println(a1.show(b));
System.out.println(a1.show(c));
System.out.println(a1.show(d));
System.out.println(a2.show(b));
System.out.println(a2.show(c));
System.out.println(a2.show(d));
System.out.println(b.show(b));
System.out.println(b.show(c));
System.out.println(b.show(d));
}
}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{
}Exception in thread "main" java.lang.NoSuchMethodError: A.show(LA;)Ljava/lang/String;
at Polymorphism.main(Polymorphism.java:9)
类A已经被指定 为什么?
A a1 = new A();
A a2 = new B();
B b = new B();
C c = new C();
D d = new D();
System.out.println(a1.show(b));
System.out.println(a1.show(c));
System.out.println(a1.show(d));
System.out.println(a2.show(b));
System.out.println(a2.show(c));
System.out.println(a2.show(d));
System.out.println(b.show(b));
System.out.println(b.show(c));
System.out.println(b.show(d));
}
} 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{ }
//-----------------------
A and A
A and A
A and D
B and A
B and A
A and D
B and B
B and B
A and D打印出来了,没有问题啊,不知道lz为什么不能运行!!