5例子6.txt

这是一本java基础教程 对新手上路有很大帮助

class A{
    int x,y;
    A(){
        x=100;
        y=200;
    }
    A(int x,int y){
        this.x=x;
        this.y=y;
    } 
}
class B extends A{
    int z;
    B(int x,int y){
        super(x,y);
        z=300; 
    }
    B(){
        super();  //可以省略
        z=800; 
    }
    public void f(){
        System.out.printf("x=%d,y=%d,z=%d\n",x,y,z);
    }
}
public class Example5_6{
    public static void main(String args[]){
        B b1=new B(10,20);
        b1.f(); 
        B b2=new B();
        b2.f();          
    }  
}