typev.java.bak

java中父类和子类对象之间的转换和变化

class A
{
	String s="A";
}
class B extends A
{
   String s="B";
}
public class TypeV
{
	public static void main(String[] args)
	{
		B b1,b2=new B();
		A a1,a2;
		a1=(A)b2;
		a2=b2;
		
		System.out.println(a1.s);
		System.out.println(a2.s);
		b1=(B)a1;
		System.out.println(b1.s);
		String ss=(A)b1.s;
		System.out.println(ss);
		
	}
}