Mega Code Archive
Shows an animated bouncing ball
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/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* Shows an animated bouncing ball.
*
* @version 1.33 2007-05-17
* @author Cay Horstmann
*/
public class Bounce {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame frame = new BounceFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}
/**
* The frame with ball component and buttons.
*/
class BounceFrame extends JFrame {
/**
* Constructs the frame with the component for showing the bouncing ball and
* Start and Close buttons
*/
public BounceFrame() {
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
setTitle("Bounce");
comp = new BallComponent();
add(comp, BorderLayout.CENTER);
JPanel buttonPanel = new JPanel();
addButton(buttonPanel, "Start", new ActionListener() {
public void actionPerformed(ActionEvent event) {
addBall();
}
});
addButton(buttonPanel, "Close", new ActionListener() {
public void actionPerformed(ActionEvent event) {
System.exit(0);
}
});
add(buttonPanel, BorderLayout.SOUTH);
}
/**
* Adds a button to a container.
*
* @param c
* the container
* @param title
* the button title
* @param listener
* the action listener for the button
*/
public void addButton(Container c, String title, ActionListener listener) {
JButton button = new JButton(title);
c.add(button);
button.addActionListener(listener);
}
/**
* Adds a bouncing ball to the panel and makes it bounce 1,000 times.
*/
public void addBall() {
try {
Ball ball = new Ball();
comp.add(ball);
for (int i = 1; i <= STEPS; i++) {
ball.move(comp.getBounds());
comp.paint(comp.getGraphics());
Thread.sleep(DELAY);
}
} catch (InterruptedException e) {
}
}
private BallComponent comp;
public static final int DEFAULT_WIDTH = 450;
public static final int DEFAULT_HEIGHT = 350;
public static final int STEPS = 1000;
public static final int DELAY = 3;
}
/*
* This program is a part of the companion code for Core Java 8th ed.
* (http://horstmann.com/corejava)
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* The component that draws the balls.
*
* @version 1.33 2007-05-17
* @author Cay Horstmann
*/
class BallComponent extends JPanel {
/**
* Add a ball to the component.
*
* @param b
* the ball to add
*/
public void add(Ball b) {
balls.add(b);
}
public void paintComponent(Graphics g) {
super.paintComponent(g); // erase background
Graphics2D g2 = (Graphics2D) g;
for (Ball b : balls) {
g2.fill(b.getShape());
}
}
private ArrayList<Ball> balls = new ArrayList<Ball>();
}
/*
* This program is a part of the companion code for Core Java 8th ed.
* (http://horstmann.com/corejava)
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* A ball that moves and bounces off the edges of a rectangle
*
* @version 1.33 2007-05-17
* @author Cay Horstmann
*/
class Ball {
/**
* Moves the ball to the next position, reversing direction if it hits one of
* the edges
*/
public void move(Rectangle2D bounds) {
x += dx;
y += dy;
if (x < bounds.getMinX()) {
x = bounds.getMinX();
dx = -dx;
}
if (x + XSIZE >= bounds.getMaxX()) {
x = bounds.getMaxX() - XSIZE;
dx = -dx;
}
if (y < bounds.getMinY()) {
y = bounds.getMinY();
dy = -dy;
}
if (y + YSIZE >= bounds.getMaxY()) {
y = bounds.getMaxY() - YSIZE;
dy = -dy;
}
}
/**
* Gets the shape of the ball at its current position.
*/
public Ellipse2D getShape() {
return new Ellipse2D.Double(x, y, XSIZE, YSIZE);
}
private static final int XSIZE = 15;
private static final int YSIZE = 15;
private double x = 0;
private double y = 0;
private double dx = 1;
private double dy = 1;
}
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