奇怪呀。。。！

      addMouseListener(new MouseAdapter()
      {
          public void mouseMoved(MouseEvent evt)
          {
              if(evt.getX()>dx1&&evt.getX()<dx2&&evt.getY()>dy1&&evt.getY()<dy2)
                  setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
              else
                  setCursor(Cursor.getDefaultCursor());
          }
          public void mousePressed(MouseEvent evt)
          {
              if(evt.getX()>dx1&&evt.getX()<dx2&&evt.getY()>dy1&&evt.getY()<dy2)
              {
                  randomSystem = r(oldintSystem);
                  randomUser = r(oldintUser);
                  oldintSystem = randomSystem;
                  oldintUser = randomUser;
              }
              paint();
          }
      });