//Ball3
//illustrates object oriented thinking
// The ball with the option to change colors
// ...and the bounce method

import java.awt.*;
import java.applet.*;

public class Ball3 extends Applet implements Runnable{

  int size;
  Color color;
  int xVal = 10;                  //X value of ball
  int yVal = 10;                  //Y value of ball  
  boolean bounceIt = false;       //says whether ball is bouncing
  boolean goingUp = false;        //says whether ball is going up or down
  Button cmdRed = new Button("Red");
  Button cmdBlue = new Button("Blue");
  Button cmdBounce = new Button("Bounce: Off");
  Thread runner; 
  
  public void start(){
    if (runner == null){
      runner = new Thread(this);    
      runner.start();
    } // end if
  } // end start;
  
  public void stop(){
    if (runner != null){
      runner.stop();
      runner = null;
    } // end if
  } // end stop
  
  public void run(){
    while(true){      //that wacky endless loop!
      if (bounceIt == true){
      
        //set new y value
        if (goingUp){    //going up
          yVal -= 10;
          //check for minimum size
          if (yVal < 0){
            goingUp = false;
          } // end if
        }else{           //going down
          yVal += 10;
          //check for maximum size
          if (yVal > this.size().height-20){
            goingUp = true;
          } // end yVal if
        } // end goingUp if      

        //change X value of ball
        xVal += 10;
        //check for maximum size
        if(xVal > this.size().width -20){
          xVal = 10;
        } // end xval if

        //pause with exception handling
        try {
          Thread.sleep(250);
        } catch (Exception e){
          showStatus(e.toString());
        } // end exception handle
      
        //draw the ball in its new position
        repaint();
      } // end bounceIt if    
    } // end while
  } // end run
  
  public void init(){
    add(cmdRed);
    add(cmdBlue);
    add(cmdBounce);
  } // end init

  public void paint(Graphics g){
    g.setColor(color);
    g.fillOval(xVal,yVal,20,20);
  }

  public boolean action(Event e, Object o){
    if (e.target == cmdRed){
      this.color = Color.red;
      repaint();
      return true;
    }else if(e.target == cmdBlue){
      this.color = Color.blue;
      repaint();
      return true;
    }else if(e.target == cmdBounce){
      bounceIt = !bounceIt;
      if (bounceIt == true){
        cmdBounce.setLabel("Bounce: On");
      }else{
        cmdBounce.setLabel("Bounce: Off");
      } // end bounceIt if
      return true;
    }else{
      return false;
    } // end if
  } // end action
  
}// end class definition