Java 基础一些代码练习笔记（多态1）

public class PolyTest4
{
public static void main (String[] args)
{
A a = null;

if(args[0].equals("1"))
{
a = new B();
}

else if(args[0].equals("2"))
{
a = new C();
}

else if(args[0].equals("3"))
{
a = new D();
}

a.method();
}
}

class A
{
public void method()
{
System.out.println("A");
}
}

class B extends A
{
public void method()
{
System.out.println("B");
}
}

class C extends A
{
public void method()
{
System.out.println("C");
}
}

class D extends A
{
public void method()
{
System.out.println("D");
}
}