一些经典的java程序适合初学者.rar

				//上转型对象2
				abstract class P
				{
					public abstract void f(int x);
					public abstract void g(int x,int y);
					public abstract void h(double x);
				}
				class S1 extends P
				{
					public void f(int x)
					{
						System.out.printf("我是S1的f,%d\n",x);
					}
					public void g(int x,int y)
					{
						System.out.printf("我市S1的g,%d,%d\n",x,y);
					}
					public void h(double x)
					{
						System.out.printf("我是S1的h,%f\n",x);
					}
				}
				class S2 extends P
				{
					public void f(int x)
					{
						System.out.printf("我是S2的f,%d\n",x);
					}
					public void g(int x,int y)
					{
						System.out.printf("我市S2的g,%d,%d\n",x,y);
					}
					public void h(double x)
					{
						System.out.printf("我是S2的h,%f\n",x);
					}
				}
				class S3 extends P
				{
					public void f(int x)
					{
						System.out.printf("我是S3的f,%d\n",x);
					}
					public void g(int x,int y)
					{
						System.out.printf("我是S3的g,%d,%d\n",x,y);
					}
					public void h(double x)
					{
						System.out.printf("我是S3的h,%f\n",x);
					}
				}
				public class Main
				{
					public static void main(String[] args)
				 {  int x=10,y=20;
				 double z=30;
				 	P p;
				 	p=new S1();
				 	p.f(x);
				 	p.g(x,y);
				 	p.h(z);
				 	p=new S2();
				 	p.f(x);
				 	p.g(x,y);
				 	p.h(z);
				 	p=new S3();
				 	p.f(x);
				 	p.g(x,y);
				 	p.h(z);
				 }
				}