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See a Working demo here

I hope this is a understandable basic introduction to a game with motion. This is a simplified classic: Pong. Our version will have three sides, one ball and one paddle. Once you get the idea, you can make a two player version, or perhaps make a "brick out" version.

We'll need:

1. a field with edges
2. a ball that has a speed and direction
3. a paddle that moves up and down
4. an app that handles user input and the passage of time

BasicPong.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.Timer;
/**
 * @author Chris Thiel, ofmcap
 * @version Sept 30, 2024
 */

public class BasicPong extends Frame implements ActionListener, MouseListener, MouseMotionListener
{
    private Timer timer;

    /**
     * These instance fields are for getting rid of flicker
     * on the Windows platform-- the App will draw the 
     * picture in memory before putting it on the screen
     */
    private Image virtualMem;
    private Graphics g0;
    private Font font;
    private String message;

    public BasicPong(Font f){

         font =f;
    }



    public BasicPong(){
        super("Basic Pong 1.0");
        setSize(500,500);
        timer = new Timer(10,this);
        font = new Font("Helvetica", Font.BOLD,  18);  
        message="Pong: click to begin";

        timer.stop();
        addMouseListener(this);
        addMouseMotionListener(this);
         this.addWindowListener(new WindowListener() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
            public void windowClosed(WindowEvent e) {}
            public void windowOpened(WindowEvent e) {}
            public void windowIconified(WindowEvent e) {}
            public void windowDeiconified(WindowEvent e) {}
            public void windowActivated(WindowEvent e) {}
            public void windowDeactivated(WindowEvent e) {}
       }); 
    }

    public void paint (Graphics g)
    {
        //make a new buffer in case the applet size changed
        virtualMem = createImage(getWidth(),getHeight());
        g0 = virtualMem.getGraphics();
        g0.setColor(Color.BLACK);
        g0.fillRect(0, 0, this.getWidth(), this.getHeight());
        g0.setColor(Color.WHITE);
        g0.setFont(font);
        g0.drawString(message, 40, 50);

        g.drawImage(virtualMem,0,0,this);//set new display to Screen
    }

    public void update(Graphics g)
    {
        paint(g); //get rid of flicker with this method
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        repaint();

    }

    @Override
    public void mouseDragged(MouseEvent e) {}

    @Override
    public void mouseMoved(MouseEvent e) {}

    @Override
    public void mouseClicked(MouseEvent e) {}

    @Override
    public void mousePressed(MouseEvent e) {}

    @Override
    public void mouseReleased(MouseEvent e) {}

    @Override
    public void mouseEntered(MouseEvent e) {}

    @Override
    public void mouseExited(MouseEvent e) {}
    public static void main(String[] args)
    {
        BasicPong app= new BasicPong();
        app.setVisible(true);
    }
}

Field Class

the field class should have the following methods:

1. A constant for the thickness of the outside wall
2. A constructor that makes two Rectangles, one for the outside and one for the area that the ball could contain
3. A draw method
4. A contains method that responds with a true if a rectangle is contains in the legal are for the ball
5. A getLeft, getRight, getTop and getBottom that returns the int corresponding to the legal ball area

Ball Class

1. A constant for the ball size (try 15)
2. A constructor that makes a bounding box of type Rectangle , initalises a deltaX and a deltaY
3. A move method that translates the bounding box Rectangle
4. A getLocation method that returns the bounding box
5. A changeX and changeY method that changes the deltaX and deltaY to the negative version of the current value
6. A draw method

import java.awt.*;
/**
 * Ball is the moving object that will
 * bounce against walls and the user's paddle
 * 
 * @author (your name)
 * @version (a version number or a date)
 * 
 * It should have:
 * 1. A constant for the ball size (try 15)
 * 2. A constructor that makes a bounding box of type Rectangle, 
 *    and initalises a deltaX and a deltaY
 * 3. A move() method that translates the bounding box Rectangle
 * 4. A getLocation() method that returns the bounding box
 * 5. The changeX() and changeY() methods that changes the deltaX 
 *    and deltaY to the negative version of the current value
 * 6. A draw(Graphics g) method to make a round white ball in 
 *    the correct place on the screen.
 */
public class Ball
{
    private static final int SIZE = 15;
    private int deltaX, deltaY;
    private Rectangle box;

    /**
     * Constructor for objects of class Ball
     */
    public Ball()
    {

    }

}

The Paddle class

1. Needs two constants for the width and height of the paddle
2. A constructor that inialises the bounding box
3. A setHeight method that sets the y location of the paddle's bounding box
4. A touches method that compares a given Rectangle with the paddles' bounding box (use the Rectangle class' intersects method.