int nsprings = 4;
  MySpring [] s = new MySpring[nsprings];
  void setup() {
    size(200, 200);
    for(int i=0; i<nsprings; i++){
      s[i] = new MySpring();
      s[i].xpos = random(width);
      s[i].ypos = random(height);
      s[i].Rx = s[i].xpos;
      s[i].Ry = s[i].ypos;
    }
  }
  void draw() {
    background(200);
    for(int i=0; i<nsprings; i++){
      if(s[i].released)s[i].move();
      ellipse(s[i].xpos, s[i].ypos , 10,10);
    }
    for(int i=0; i<nsprings-1; i++)
      line(s[i].xpos, s[i].ypos ,s[i+1].xpos, s[i+1].ypos);
  }
  void mouseDragged() {
    for(int i=0; i<nsprings; i++)
      if(dist(mouseX,mouseY,s[i].xpos,s[i].ypos)<10){
        s[i].released = false;
        s[i].xpos = mouseX;
        s[i].ypos = mouseY;
      }
  }
  void mouseReleased(){
    for(int i=0; i<nsprings; i++)
      s[i].released = true;
  }