I need help on moving the small box created to move smoothly as I click and drag near the outside layer. Here is my code:

Question

So i have the following code. basically what it does is get current location of x and y. If the user clicks inside the block, move the block so it wont be as jumpy.

public void mouseDragged(MouseEvent arg0) {
    Graphics g = getGraphics();


     x = arg0.getX();
     y = arg0.getY();
   if(x>= oldx || x<= oldx+20 && y>=oldy || y<=oldy+20){
    g.clearRect(oldx, oldy, 20, 20);
    g.fillRect(oldx, oldy+20, 20, 20);



    if(arg0.getX() == oldx && arg0.getY() == oldy){


    }else{
        g.clearRect(oldx, oldy+20, 20, 20);
        g.fillRect(arg0.getX(),  arg0.getY()+20, 20, 20);
        oldx = arg0.getX();
        oldy = arg0.getY();


    }
   }

}