public class MoveCanvas extends Canvas{
          int x = 20;
          
          public void paint(Graphics g){
               g.drawRect(x,50,20,10);
          }

          public void keyPressed(int keyCode){
                int action = getGameAction(keyCode);
                switch(action){
                case LEFT:
                    x--;
                    break;
                case RIGHT:
                    x++;
                    break;
                }
                repaint();
          }
          
}