効率の良い描画方法とは？

import java.awt.*;

import java.awt.event.*;



public class sample7{



	public static void main (String [] args){

		frames f = new frames ();

		f.addWindowListener (new WindowAdapter (){

			public void windowClosing (WindowEvent e){

				System.exit (0);

			}

		});

		f.setSize (1000, 400);

		f.show ();

	}



}



class frames extends Frame{



	frames (){

		setLayout (new GridLayout (2, 5));

		for (int i = 0;i < 10; i++){

			add (new panels ("Panel" + i));

		}

	}



	public void update (Graphics g){

		paint (g);

	}



}



class panels extends Component implements Runnable{



	private int gWidth = 200;

	private int gHeight = 200;

	private Image image1, image2, currentImage, offImage;

	private Graphics offGraphics;

	private Thread thread;

	private String text;

	private String currentText;

	private int px = 240;

	private static Font font = new Font ("Serif", Font.BOLD, 20);

	private boolean setInit = false;



	public panels (String mtext){

		enableEvents (AWTEvent.MOUSE_EVENT_MASK | AWTEvent.FOCUS_EVENT_MASK);

		MediaTracker tracker = new MediaTracker (this);

		image1 = Toolkit.getDefaultToolkit ().createImage (getClass ().getResource ("1.jpg"));

		image2 = Toolkit.getDefaultToolkit ().createImage (getClass ().getResource ("2.jpg"));

		tracker.addImage (image1, 0);

		tracker.addImage (image2, 0);

		text = mtext;

		try{

			tracker.waitForAll ();

		}

		catch (InterruptedException ex){

		}

		handleFocus (false);

		thread = new Thread (this);

		thread.start();

	}



	public void paint (Graphics g){

		if (!setInit){

			offImage = this.createImage (gWidth, gHeight);

			offGraphics = offImage.getGraphics ();

			setInit = true;

		}

		offGraphics.clearRect (0, 0, gWidth, gHeight);

		offGraphics.drawImage (currentImage, 0, 0, gWidth, gHeight, this);

		offGraphics.setColor (Color.white);

		offGraphics.setFont (font);

		offGraphics.drawString (currentText, px, 90);

		g.drawImage (offImage, 0, 0, this);

	}



	public void run (){

		boolean j = true;

		try{

			while (j){

				Thread.sleep (50);

				--px;

				if (px < -80) px = 240;

				repaint ();

			}

		}

		catch (Exception e){

		}

	}



	private void handleFocus (boolean value){

		if (value){

			currentImage = image2;

			currentText = text;

		}

		else{

			currentImage = image1;

			currentText = "";

		}

		repaint ();

	}



	public boolean isFocusTraversable (){

		return true;

	}



	protected void processMouseEvent (MouseEvent e){

		if (e.getID() == MouseEvent.MOUSE_PRESSED){

			requestFocus ();

		}

		super.processMouseEvent (e);

	}



	protected void processFocusEvent (FocusEvent e){

		switch (e.getID()){

			case FocusEvent.FOCUS_GAINED:

				handleFocus (true);

			break;

			case FocusEvent.FOCUS_LOST:

				handleFocus (false);

			break;

		}

		super.processFocusEvent (e);

	}



}