reboundpanel.java help!

hi everyone!
there are a few questions that I'd like to ask regarding a particular problem.
I havent seen an entry like this before... so if this is inappropriate, please delete this thread!

here's the program code....


//********************************************************************
// ReboundPanel.java Author: Lewis/Loftus
//
// Represents the primary panel for the Rebound program.
//********************************************************************

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ReboundPanel extends JPanel
{
private final int WIDTH = 300, HEIGHT = 100;
private final int DELAY = 20, IMAGE_SIZE = 35;

private ImageIcon image;
private Timer timer;
private int x, y, moveX, moveY;

//-----------------------------------------------------------------
// Sets up the panel, including the timer for the animation.
//-----------------------------------------------------------------
public ReboundPanel()
{
timer = new Timer(DELAY, new ReboundListener());

image = new ImageIcon ("happyFace.gif");

x = 0;
y = 40;
moveX = moveY = 3;

setPreferredSize (new Dimension(WIDTH, HEIGHT));
setBackground (Color.black);
timer.start();
}

//-----------------------------------------------------------------
// Draws the image in the current location.
//-----------------------------------------------------------------
public void paintComponent (Graphics page)
{
super.paintComponent (page);
image.paintIcon (this, page, x, y);
}

//*****************************************************************
// Represents the action listener for the timer.
//*****************************************************************
private class ReboundListener implements ActionListener
{
//--------------------------------------------------------------
// Updates the position of the image and possibly the direction
// of movement whenever the timer fires an action event.
//--------------------------------------------------------------
public void actionPerformed (ActionEvent event)
{
x += moveX;
y += moveY;

if (x <= 0 || x >= WIDTH-IMAGE_SIZE)
moveX = moveX * -1;

if (y <= 0 || y >= HEIGHT-IMAGE_SIZE)
moveY = moveY * -1;

repaint();
}
}
}


Questions I'd like to ask....

1. How do I move the smiley diagonally? I've tried experimenting with the moveX and moveY values, but to no avail. So, I don't really understand my java well... :(

2. At this stage, the smiley will run out of the window (right and bottom sides). Smiley should bounce back as soon as it touches the 4 sides of the window.
Write down the steps you take to solve this problem.

3. Using array implement 2 bouncing smileys. does this mean just declaring the necessary variables etc to get a second smiley??

4. Implement such that when i click the mouse on this window, the 2 bouncing smileys will stop. The next clicked will make them move again.

can anyone be patient & kind to guide me along? thanks much.

ps. the alightment might be slightly altered due to the textbox.

I actually had to do this program before, but I used objectdraw rather than swing.

The trick is that the action performed doesn't need to use "if...else..." as you implemented it.

The solution that I would use is create two booleans "moveXRight" and "moveYUp" or something to those effects.

What you do then is IF x == WIDTH-IMAGE_SIZE THEN moveXRight = false. You also need another one IF x==0 THEN moveXRight = true. :)

//checks if it reaches a side
//if it has reached a side, it changes direction
//otherwise it keeps going in its direction
if((moveXRight == false && moveX>0)||(moveXRight == true && moveX<0))
moveX*=-1;

Then you do the same thing with moveY.

In my program, I made the ball move randomly in the X direction and randomly in the Y direction (though the random number was between 0 and 1 so I had control over the direction ;)).

You would have to implement this in the actionPerformed method.

Goodluck!

thanks for replying! i'll try that soon.