public class SleepMethodTest extends JFrame { private Thread t; private static Color[] color = { Color.BLACK, Color.BLUE, Color.CYAN, Color.GREEN, Color.ORANGE, Color.YELLOW, Color.RED }; private static final Random rand = new Random(); private static Color getC() { return color[rand.nextInt(color.length)]; } public SleepMethodTest() { // TODO Auto-generated constructor stub t = new Thread(new Runnable() { int x = 30; int y = 50; public void run() { while (true) { try { Thread.sleep(100); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } Graphics graphics = getGraphics(); graphics.setColor(getC()); graphics.drawLine(x, y, 100, y++); if(y>=80){ y=50; } } } }); t.start(); } public static void init(JFrame frame,int width,int height) { frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(width, height); frame.setVisible(true); } public static void main(String[] args) { // TODO Auto-generated method stub init(new SleepMethodTest(), 100, 100); } }