Moving Ball Using Thread in Java Example

import java.awt.*;


import java.awt.event.*;


import java.applet.*;


/*<applet code="MovingBalls" width=500 height=250> </applet>*/


public class MovingBalls extends Applet implements ActionListener,Runnable


{


        int d=100;


        Thread t;


        Button btnStart,btnStop,btnPause,btnResume;


        int i,m,j;


        TextField txtSpeed;


        Label lblSpeed;


        public void init()


           {


               lblSpeed=new Label("Enter speed in ms");


               txtSpeed=new TextField(5);


               btnStart=new Button("Start");


               btnStop=new Button("Stop");


               btnPause=new Button("Pause");


               btnResume=new Button("Resume");


               btnStart.addActionListener(this);


               btnStop.addActionListener(this);


               btnPause.addActionListener(this);


               btnResume.addActionListener(this);


               add(lblSpeed);


               add(txtSpeed);


               add(btnStart);


               add(btnStop);


               add(btnPause);


               add(btnResume);


           }


              public void actionPerformed(ActionEvent ae)


                {


                     if((ae.getSource()==btnStart)&&(t==null))


                      {


                           t = new Thread(this);


                           t.start();


                       }


                      else if((ae.getSource()==btnStop)&&(t != null))


                       {


                           t.stop();


                           t=null;


                       }


                     else if((ae.getSource()==btnPause)&&(t != null))


                       {


                          t.suspend();


                       }


                    else if((ae.getSource()==btnResume)&&(t != null))


                       {


                            t.resume();


                        }


                 }


                     public void run()


                       {


                           m=((int)(Math.random()*1000))%700;


                           for(j=500;;j--)


                               {


                                  if(j<-1000)


                                    {


                                       m=((int)(Math.random()*1000))%700;


                                        j=500;


                                    }


                                  repaint();


                                  try


                                    {


                                        Thread.sleep(Integer.parseInt(txtSpeed.getText()));


                                    }


                                        catch(Exception e){}


                                }


                         }


             public void paint(Graphics g)


          {


                for(int k=0,i=d;i>0;i--,k++)


                      {


                           g.setColor(new Color(100+k,100,100+k));


                           g.drawOval((m+200)%700+k/2,k/2+j,i,i);


                       }


                          for(int k=0,i=d;i>0;i--,k++)


                             {


                                   g.setColor(new Color(100+k,200,80+k));


                                   g.drawOval(k/2+(m%700),k/2+j,i,i);


                              }


                         for(int k=0,i=d;i>0;i--,k++)


                            {


                                   g.setColor(new Color(10+k,40,90+k));


                                   g.drawOval(k/2+(m+500)%700,k/2+j,i,i);


                            }


             }


}