You'll find the Double Buffer Panel source against flickering. 

           
      /*
       * @(#)DoubleBufferPanel.java   1.2 97/01/14 Jeff Dinkins
       */             
     package java.awt;
      import java.awt.*;
      import java.applet.*;

      public class DoubleBufferPanel extends Panel {
        Image offscreen;

        /**
         * null out the offscreen buffer as part of invalidation
         */
        public void invalidate() {
            super.invalidate();
            offscreen = null;
        }

        /**
         * override update to *not* erase the background before painting
         */
        public void update(Graphics g) {
            paint(g);
        }

        /**
         * paint children into an offscreen buffer, then blast entire image
         * at once.
         */
        public void paint(Graphics g) {
            if(offscreen == null) {
               offscreen = createImage(getSize().width, getSize().height);
            }

            Graphics og = offscreen.getGraphics();
            og.setClip(0,0,getSize().width, getSize().height);
            super.paint(og);
            g.drawImage(offscreen, 0, 0, null);
            og.dispose();
        }

      }