Исходные тексты аплета Rectangles приведены в листинге 1.

Листинг 1. Файл Rectangles,java

import java.applet.*;
import java.awt.*;
public class Rectangles
	extends Applet
{
  DrawRectangles m_DrawRectThread =
                         null;
  DrawEllipse m_DrawEllipseThread =
                         null;
  NotifyTask m_NotifyTaskThread =
                         null
  public String getAppletInfo()
  {
    return "Name: Rectangles";
  }
  public void paint(Graphics g)
  {
    Dimension dimAppWndDimension = getSize();
    g.setColor(Color.yellow);
    g.fillRect(0, 0,
      dimAppWndDimension.width  - 1,
      dimAppWndDimension.height - 1);
    g.setColor(Color.black);
    g.drawRect(0, 0,
      dimAppWndDimension.width  - 1,
      dimAppWndDimension.height - 1);
  }
  public void start()
  {
    if (m_DrawRectThread == null)
    {
      m_DrawRectThread =
        new DrawRectangles(this);
      m_DrawRectThread.start();
    }
    if (m_DrawEllipseThread == null)
    {
      m_DrawEllipseThread =
        new DrawEllipse(this);
      m_DrawEllipseThread.start();
    }
    if (m_NotifyTaskThread == null)
    {
      m_NotifyTaskThread =
        new NotifyTask(m_DrawEllipseThread);
      m_NotifyTaskThread.start();
    }
  }

  public void stop()
  {
    if (m_DrawRectThread != null)
    {
      m_DrawRectThread.stop();
      m_DrawRectThread = null;
    }
    if (m_DrawEllipseThread == null)
    {
      m_DrawEllipseThread.stop();
      m_DrawEllipseThread = null;
    }
    if (m_NotifyTaskThread != null)
    {
      m_NotifyTaskThread.stop();
      m_NotifyTaskThread = null;
    }
  }
}
class DrawRectangles extends Thread
{
  Graphics g;
  Dimension dimAppWndDimension;
  public DrawRectangles(Applet Appl)
  {
    g = Appl.getGraphics();
    dimAppWndDimension = Appl.getSize();
  }
  public void run()
  {
    while (true)
    {
      int x, y, width, height;
      int rColor, gColor, bColor;
      x =      (int)(dimAppWndDimension.width
            * Math.random());
      y =      (int)(dimAppWndDimension.height
            * Math.random());
      width  = (int)(dimAppWndDimension.width
            * Math.random()) / 2;
      height = (int)(dimAppWndDimension.height
            * Math.random()) / 2;
      rColor = (int)(255 * Math.random());
      gColor = (int)(255 * Math.random());
      bColor = (int)(255 * Math.random());
      g.setColor(new Color(rColor,
        gColor, bColor));
      g.fillRect(x, y, width, height);
      try
      {
	Thread.sleep(50);
      }
      catch (InterruptedException e)
      {
	stop();
      }
    }
  }
}
class DrawEllipse extends Thread
{
  Graphics g;
  Dimension dimAppWndDimension;
  public DrawEllipse(Applet Appl)
  {
    g = Appl.getGraphics();
    dimAppWndDimension = Appl.getSize();
  }
  public synchronized void run()
  {
    while (true)
    {
      int x, y, width, height;
      int rColor, gColor, bColor;
      x =      (int)(dimAppWndDimension.width
          * Math.random());
      y =      (int)(dimAppWndDimension.height
          * Math.random());
      width  = (int)(dimAppWndDimension.width
          * Math.random()) / 2;
      height = (int)(dimAppWndDimension.height
          * Math.random()) / 2;
      rColor = (int)(255 * Math.random());
      gColor = (int)(255 * Math.random());
      bColor = (int)(255 * Math.random());
      g.setColor(new Color(rColor,
         gColor, bColor));
      g.fillOval(x, y, width, height);
      try
      {
	this.wait();
      }
      catch (InterruptedException e)
      {
      }
    }
  }
}
class NotifyTask extends Thread
{
  Thread STask;
  public NotifyTask(Thread SynchroTask)
  {
    STask = SynchroTask;
  }
  public void run()
  {
    while (true)
    {
      try
      {
	Thread.sleep(30);
      }
      catch (InterruptedException e)
      {
      }
      synchronized(STask)
      {
        STask.notify();
      }
    }
  }
}