问答题

【说明】一条直线是由两个点组成的，代码如下。
public class Point

private int x, y; //coordinate
public Point (int x, int y)
(1) =x; (2) ;
public int GetX()
return x;
public int GetY()
return y;

class Line //line segment

private (3) ; //extremc points
Line (Point a, Point b) //constructor
p1 = (4) ;
p2= (5) ;

public double Length()
return Math.sqrt (Math.pow (p2.GetX()-pl.GetX(),2)
+Math.pow (p2.GetY()-p1.GetY(),2)) ;