Bouncing Ball

Hello friends, we are going to make a ball which bounce back whenever touches the window. Open your IntelliJ or any other IDE and create a new Project. Now, name this project whatever you likes and go to Main.java file.

Now, write the following code in Main.java file.

Main.java :

import javax.swing.*;


public class Main extends JPanel {
  public static int height = 600;
  public static int width = 600;

  public static void main(String[] args) {
    JFrame obj = new JFrame();
    Ball ball = new Ball();

    obj.setBounds(100,100,width,height);
    obj.setTitle("Bouncing Ball");
    obj.setResizable(false);
    obj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    obj.add(ball);
    obj.setVisible(true);
  }
}

Now, go to Projects tab.
Right Click on src folder, go to New and Click on JAVA Class.
Name the new JAVA Class as Ball.java
Write the following code in Ball.java.

Ball.java :

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


public class Ball extends JPanel {
  public static int diameter = 50;
  public int x = 250;
  public int y = 250;
  public int velocityX = 10;
  public int velocityY = 10;
  public int interval = 20;
  public Timer timer;

  public Ball() {
    timer = new Timer(interval, new TimerAction());
    timer.start();
  }

  class TimerAction implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      move();
      repaint();
    }
  }

  public void move() {
    x += velocityX;
    y += velocityY;

    if (x < 0) {
      x = 0;
      velocityX = -velocityX;
    }
    else if (x > getWidth() - diameter) {
      velocityX = -velocityX;
    }
    if (y < 0) {
      y = 0;
      velocityY = -velocityY;
    }
    else if (y > getHeight() - diameter) {
      velocityY = -velocityY;
    }
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);

    g.setColor(Color.RED);
    g.fillOval(x, y, diameter, diameter);
  }
}

Other JAVA projects :
Ball Game using JAVA
Notepad using JAVA
Chat Application using JAVA
Simple Clock using JAVA