testextend.java

java程序设计 清华出版社 孙燮华老师编写的程序源代码

//testExtend.java
class Point{
  int x,y;
  
  public Point(int i, int j){
  	x=i; y=j;
  }
  
  public double distance(){
    return Math.sqrt(x*x+y*y);
  }
}

class Point3 extends Point{
  int z;
  
  public Point3(int i,int j,int k){
  	super(i,j); 
  	z=k;
  }
  
  public double distance(){
    return Math.sqrt(x*x+y*y+z*z);
  }
}

public class testExtend{
  public static void main(String args[]){
    Point p = new Point(1, 1);
    System.out.println("p.distance() = " + p.distance());
    p = new Point3(1, 1, 1);
    System.out.println("p.distance() = " + p.distance());
  }
}