Take the code for the Bouncing Ball Java Applet and make the ball bigger, but bo

Question

Take the code for the Bouncing Ball Java Applet and make the ball bigger, but bounce slower!

Paste your source code and output below.

Take the code for the various graphics that were demonstrated and …

Show a triangle, square, rectangle and circle in one frame or panel;

See if you can fill the geometric shapes with color!

Triangle – red

Square – yellow

Rectangle – blue

Circle – green

Draw a house with a tree using Java Graphics (and challenge: the stick figure!). Paste your source code and output below the figure below.

Explanation / Answer

Answer:

BouncingBallSimple.java:

/*Writing a single ball bouncing inside a rectangular container box is straight forward, and can be accomplished with very few lines of codes, as follows*/

import java.awt.*;

import java.util.Formatter;

import javax.swing.*;
/**
* One ball bouncing inside a rectangular box.
* All codes in one file. Poor design!
*/
// Extends JPanel, so as to override the paintComponent() for custom rendering codes.
public class BouncingBallSimple extends JPanel {
// Container box's width and height
private static final int BOX_WIDTH = 640;
private static final int BOX_HEIGHT = 480;
  
// Ball's properties
private float ballRadius = 200; // Ball's radius
private float ballX = ballRadius + 50; // Ball's center (x, y)
private float ballY = ballRadius + 20;
private float ballSpeedX = 3; // Ball's speed for x and y
private float ballSpeedY = 2;
  
private static final int UPDATE_RATE = 30; // Number of refresh per second
  
/** Constructor to create the UI components and init game objects. */
public BouncingBallSimple() {
this.setPreferredSize(new Dimension(BOX_WIDTH, BOX_HEIGHT));
  
// Start the ball bouncing (in its own thread)
Thread gameThread = new Thread() {
public void run() {
while (true) { // Execute one update step
// Calculate the ball's new position
ballX += ballSpeedX;
ballY += ballSpeedY;
// Check if the ball moves over the bounds
// If so, adjust the position and speed.
if (ballX - ballRadius < 0) {
ballSpeedX = -ballSpeedX; // Reflect along normal
ballX = ballRadius; // Re-position the ball at the edge
} else if (ballX + ballRadius > BOX_WIDTH) {
ballSpeedX = -ballSpeedX;
ballX = BOX_WIDTH - ballRadius;
}
// May cross both x and y bounds
if (ballY - ballRadius < 0) {
ballSpeedY = -ballSpeedY;
ballY = ballRadius;
} else if (ballY + ballRadius > BOX_HEIGHT) {
ballSpeedY = -ballSpeedY;
ballY = BOX_HEIGHT - ballRadius;
}
// Refresh the display
repaint(); // Callback paintComponent()
// Delay for timing control and give other threads a chance
try {
Thread.sleep(1000 / UPDATE_RATE); // milliseconds
} catch (InterruptedException ex) { }
}
}
};
gameThread.start(); // Callback run()
}
  
/** Custom rendering codes for drawing the JPanel */
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g); // Paint background
  
// Draw the box
g.setColor(Color.BLUE);
g.fillRect(0, 0, BOX_WIDTH, BOX_HEIGHT);

// Draw the triangle
g.setColor(Color.RED);
g.fillPolygon((int) (ballX - ballRadius), (int) (ballY - ballRadius),
(int)(2 * ballRadius), (int)(2 * ballRadius));
// Draw the square
g.setColor(Color.YELLOW);
g.fillSquare((int) (ballX - ballRadius), (int) (ballY - ballRadius),
(int)(2 * ballRadius), (int)(2 * ballRadius));
  
// Draw the ball
g.setColor(Color.GREEN);
g.fillOval((int) (ballX - ballRadius), (int) (ballY - ballRadius),
(int)(2 * ballRadius), (int)(2 * ballRadius));
  
// Display the ball's information
g.setColor(Color.WHITE);
g.setFont(new Font("Courier New", Font.PLAIN, 12));
StringBuilder sb = new StringBuilder();
Formatter formatter = new Formatter(sb);
formatter.format("Ball @(%3.0f,%3.0f) Speed=(%2.0f,%2.0f)", ballX, ballY,
ballSpeedX, ballSpeedY);
g.drawString(sb.toString(), 20, 30);
}
  
/** main program (entry point) */
public static void main(String[] args) {
// Run GUI in the Event Dispatcher Thread (EDT) instead of main thread.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
// Set up main window (using Swing's Jframe)
JFrame frame = new JFrame("A Bouncing Ball");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new BouncingBallSimple());
frame.pack();
frame.setVisible(true);
}
});
}
}

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