this.xpoints = new int[npoints]; this.ypoints = new int[npoints]; System.arraycopy(xpoints, 0, this.xpoints, 0, npoints); System.arraycopy(ypoints, 0, this.ypoints, 0, npoints); this.npoints = npoints;
xpoints = new int[4]; ypoints = new int[4];
  public Polygon(int[] xpoints, int[] ypoints, int npoints)  {    this.xpoints = new int[npoints];    this.ypoints = new int[npoints];    System.arraycopy(xpoints, 0, this.xpoints, 0, npoints);    System.arraycopy(ypoints, 0, this.ypoints, 0, npoints);    this.npoints = npoints;  }