刚学java不久

//求两个点之间的距离，看java视频时发现的问题

class Point {
  double x,y,z;
  Point (double _x,double _y,double _z ){
   x=_x;
   y=_y;
   z=_z;
  }
  void setX(double _x){
   x=_x;
  }
  void setY(double _y){
   y=_y;
  }
  void setZ(double _z){
   z=_z;
  }
  double getDistance(Point p){
   return (x-p.x)*(x-p.x)+(y-p.y)*(y-p.y)+(z-p.z)*(z-p.z);
  }
}
 public class TestPiont{
  public static void main(String[] args){
   Point p=new Point(1.0,2.0,3.0);
   Point p1=new Point(0.0,0.0,0.0);
   System.out.println(p.getDistance(p1));
   p.setX(5.0);
   System.out.println(p.getDistance(new Point(1.0,1.0,1.0)));
  }
 }

运行时总说有个错误，我不知哪出错误了？