第一個包

package Mypack;

public class Point {
        public double x,y;
        public Point(double a,double b)
        {
            x=a;
            y=b;
        }
        public double distanceTo(Point p){
            return Math.sqrt((x-p.x)*(x-p.x)+(y-p.y)*(y-p.y));  
    }
}

第二個包

package Test;
import Mypack.Point;

public
 
 class UsePoint {
    public static void main(String[] args)
    {
        Point p1=new Point(1.0,2.0);
        Point p2=new Point(2.0, 5.5);
        System.out.println("點p1座標："+p1.x+","+p1.y);
        System.out.println("點p2座標："+p2.x+","+p2.y);
        System.out.println("點p1到點p2的距離："+p1.distanceTo(p2));
    }

}
 

結果點p1座標：1.0,2.0
點p2座標：2.0,5.5
點p1到點p2的距離：3.640054944640259