Graphics g = this.jPanel1.getGraphics();

    int x1,x2,y1,y2,xn,yn,xi,yi,pn,dx,dy,i;

    x1 = Integer.parseInt(this.x1.getText());
    x2 = Integer.parseInt(this.x2.getText());
    y1 = Integer.parseInt(this.y1.getText());
    y2 = Integer.parseInt(this.y2.getText());

    i = 0;

    xn = x1;
    yn = y1;

    dx = Math.abs(x2-x1);
    dy = Math.abs(y2-y1);

    if (x1<x2)
    {
        xi = 1;

    }

    else

   {
       xi = -1;
   }
    if (y1<y2)
    {
        yi = 1;

    }

    else

   {
       yi = -1;
   }

   g.drawLine(x1, y1, x2, y2);

   if (dx>dy);
   {
       pn = 2*dy-dx;
       i++;
       this.jTextArea1.append(String.valueOf(i) + ") xn= "
               + String.valueOf(xn) + " yn = "
                + String.valueOf(yn) + " Pn = "
                + String.valueOf(pn) + "\n");
       while(xn!=x2)
       {
           if(pn>0)

           {
               xn = xn + xi;
               yn = yn + yi;
               pn = pn + 2*dy-2*dx;



           }

           else
           {
           pn = 2*dy-dx;
           pn = pn*dy;

       this.jTextArea1.append(String.valueOf(i) + ") xn= "
               + String.valueOf(xn) + " yn = "
                + String.valueOf(yn) + " Pn = "
                + String.valueOf(pn) + "\n");






           }



      }


   if (dx<dy);
   {

       pn = 2*dx-dy;
       i++;
       this.jTextArea1.append(String.valueOf(i) + ") xn= "
               + String.valueOf(xn) + " yn = "
                + String.valueOf(yn) + " Pn = "
                + String.valueOf(pn) + "\n");
       while(yn!=y2)
       {
           if(pn>0)

           {
               xn = xn + xi;
               yn = yn + yi;
               pn = pn + 2*dx-2*dy;


           }

           else
           {
           pn = 2*dx-dy;
           pn = pn*dx;

       this.jTextArea1.append(String.valueOf(i) + ") xn= "
               + String.valueOf(xn) + " yn = "
                + String.valueOf(yn) + " Pn = "
                + String.valueOf(pn) + "\n");


           }
           g.drawLine(xn, yn, xn, yn);
       }
   }}