How to code a Simple Swing Game using Java?

Problem Statement:

Write a simple swing animation program using Java. Two buttons to start the animation and to close exit the window. You can use javax.swing.* package and java.awt.* package.

Solution

The problem statement is somewhat vague. It only conveys the idea to develop a swing application with animation using Swing / AWT packages in Java. Let us create a simple ball game with simple animation.

We can compile and run Swing applications like any other java programs. Program that uses Swing/AWT components need to import the following packages:

 

Java Code

java.awt.*;
javax.swing.*;

public class BallGame {
 public static void main(String[] args) {
 JFrame roomFrame = new Room();
 roomFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); roomFrame.setVisible(true);
 }
}

Room

class Room extends JFrame
{
 private static final long serialVersionUID = 1L;
 private RoomPanel rPanel;
 public static final int WIDTH = 750;
 public static final int HEIGHT = 600;

 public Room()
 {
 setSize(WIDTH, HEIGHT);
 setTitle("GameRoom");

 Container contentPane = getContentPane();
 rPanel = new RoomPanel();
 contentPane.add(rPanel, BorderLayout.CENTER);
 JPanel buttonPanel = new JPanel();
 addButton(buttonPanel, "Game Start",
 new ActionListener()
 {
 public void actionPerformed(ActionEvent event)
 {
 addGameObject();
 }
 });

 addButton(buttonPanel, "Game Close",
 new ActionListener()
 {
 public void actionPerformed(ActionEvent event)
 {
 System.exit(0);
 }


 });
 contentPane.add(buttonPanel, BorderLayout.SOUTH);
 }

 public void addButton(Container c, String title,
 ActionListener listener)
 {
 JButton button = new JButton(title);
 c.add(button);
 button.addActionListener(listener);
 }

 public void addGameObject()
 {
 try
 {
 BallGameObject b = new BallGameObject(rPanel);
 rPanel.add(b);
 for (int i = 1; i <= 200; i++)
 {
 b.play();
 Thread.sleep(50);
 }
 }
 catch (InterruptedException ie)
 {
 ie.printStackTrace();
 }
 }
}

 

RoomPanel

class RoomPanel extends JPanel
{
 private static final long serialVersionUID = 1L;
 private ArrayList<BallGameObject> gameObjects = new ArrayList<BallGameObject>();

 public void add(BallGameObject b)
 {
 gameObjects.add(b);
 }

 public void paintComponent(Graphics g)
 {
 super.paintComponent(g);
 Graphics2D g2 = (Graphics2D)g;
 for (int i = 0; i < gameObjects.size(); i++)
 {
 BallGameObject b = (BallGameObject)gameObjects.get(i);
 b.draw(g2);
 }
 }
}




class BallGameObject
{
 private Component component;
 private static final int WIDTH = 60;
 private static final int HEIGTH = 60;
 private int x = 0;
 private int y = 0;
 private int dx = 10;
 private int dy = 10;

 public BallGameObject(Component c) { component = c; }

 public void draw(Graphics2D g2)
 {
 g2.fill(new Ellipse2D.Double(x, y, WIDTH , HEIGTH ));
 g2.setColor(Color.GREEN);
 }

 public void play()
 {
 x += dx;
 y += dy;
 if (x < 0)
 {
 x = 0;
 dx = -dx;
 }
 if (x + WIDTH >= component.getWidth())
 {
 x = component.getWidth() - WIDTH ;
 dx = -dx;
 }
 if (y < 0)
 {
 y = 0;
 dy = -dy;
 }
 if (y + HEIGTH >= component.getHeight())
 {
 y = component.getHeight() - HEIGTH ;
 dy = -dy;
 }

 component.paint(component.getGraphics());
 }
}

Output