Javaで以下のようなものを作りたいのですが、さっぱりで困ってます…

こちらを参考にして できないでしょうか?

import java.awt.*;

import java.awt.event.*;

public class Test extends Frame implements Runnable {

private final int FRAME_WIDTH = 400;

private final int FRAME_HEIGHT = 400;

private final int SQUARE_SIZE = 20;

private final int MOVE_SIZE = 1;

private final int SLEEP_TIME = 10;

private int oldX, oldY, nowX, nowY;

public Test() {

setSize(FRAME_WIDTH, FRAME_HEIGHT);

nowX = nowY = 0;

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent evt) {

System.exit(0);

}

});

setVisible(true);

}

public void paint(Graphics g) {

g.setColor(Color.white);

g.fillRect(oldX, oldY, SQUARE_SIZE, SQUARE_SIZE);

g.setColor(Color.blue);

g.fillRect(nowX, nowY, SQUARE_SIZE, SQUARE_SIZE);

}

public void update(Graphics g) {

paint(g);

}

public void run() {

while(true) {

oldX = nowX;

oldY = nowY;

nowX += MOVE_SIZE;

nowY += MOVE_SIZE;

if(nowX >= FRAME_WIDTH || nowY >= FRAME_HEIGHT) {

nowX = nowY = 0;

}

repaint();

try {Thread.sleep(SLEEP_TIME);}

catch(InterruptedException e) {}

}

}

public static void main(String args[]) {

Test test = new Test();

Thread thread = new Thread(test);

thread.run();

}

}

こんなのじゃだめですか？