public class BounceThread
class BallRunnable implements Runnable
class Ball
class BallPanel extends JPanel
class BounceFrame extends JFrame
1: /**
2: @version 1.32 2004-07-27
3: @author Cay Horstmann
4: */
5:
6: import java.awt.*;
7: import java.awt.event.*;
8: import java.awt.geom.*;
9: import java.util.*;
10: import javax.swing.*;
11:
12: /**
13: Shows an animated bouncing ball.
14: */
15: public class BounceThread
16: {
17: public static void main(String[] args)
18: {
19: JFrame frame = new BounceFrame();
20: frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
21: frame.setVisible(true);
22: }
23: }
24:
25: /**
26: A runnable that animates a bouncing ball.
27: */
28: class BallRunnable implements Runnable
29: {
30: /**
31: Constructs the runnable.
32: @aBall the ball to bounce
33: @aPanel the component in which the ball bounces
34: */
35: public BallRunnable(Ball aBall, Component aComponent)
36: {
37: ball = aBall;
38: component = aComponent;
39: }
40:
41: public void run()
42: {
43: try
44: {
45: for (int i = 1; i <= STEPS; i++)
46: {
47: ball.move(component.getBounds());
48: component.repaint();
49: Thread.sleep(DELAY);
50: }
51: }
52: catch (InterruptedException e)
53: {
54: }
55: }
56:
57: private Ball ball;
58: private Component component;
59: public static final int STEPS = 1000;
60: public static final int DELAY = 5;
61: }
62:
63: /**
64: A ball that moves and bounces off the edges of a
65: rectangle
66: */
67: class Ball
68: {
69: /**
70: Moves the ball to the next position, reversing direction
71: if it hits one of the edges
72: */
73: public void move(Rectangle2D bounds)
74: {
75: x += dx;
76: y += dy;
77: if (x < bounds.getMinX())
78: {
79: x = bounds.getMinX();
80: dx = -dx;
81: }
82: if (x + XSIZE >= bounds.getMaxX())
83: {
84: x = bounds.getMaxX() - XSIZE;
85: dx = -dx;
86: }
87: if (y < bounds.getMinY())
88: {
89: y = bounds.getMinY();
90: dy = -dy;
91: }
92: if (y + YSIZE >= bounds.getMaxY())
93: {
94: y = bounds.getMaxY() - YSIZE;
95: dy = -dy;
96: }
97: }
98:
99: /**
100: Gets the shape of the ball at its current position.
101: */
102: public Ellipse2D getShape()
103: {
104: return new Ellipse2D.Double(x, y, XSIZE, YSIZE);
105: }
106:
107: private static final int XSIZE = 15;
108: private static final int YSIZE = 15;
109: private double x = 0;
110: private double y = 0;
111: private double dx = 1;
112: private double dy = 1;
113: }
114:
115: /**
116: The panel that draws the balls.
117: */
118: class BallPanel extends JPanel
119: {
120: /**
121: Add a ball to the panel.
122: @param b the ball to add
123: */
124: public void add(Ball b)
125: {
126: balls.add(b);
127: }
128:
129: public void paintComponent(Graphics g)
130: {
131: super.paintComponent(g);
132: Graphics2D g2 = (Graphics2D) g;
133: for (Ball b : balls)
134: {
135: g2.fill(b.getShape());
136: }
137: }
138:
139: private ArrayList<Ball> balls = new ArrayList<Ball>();
140: }
141:
142: /**
143: The frame with panel and buttons.
144: */
145: class BounceFrame extends JFrame
146: {
147: /**
148: Constructs the frame with the panel for showing the
149: bouncing ball and Start and Close buttons
150: */
151: public BounceFrame()
152: {
153: setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
154: setTitle("BounceThread");
155:
156: panel = new BallPanel();
157: add(panel, BorderLayout.CENTER);
158: JPanel buttonPanel = new JPanel();
159: addButton(buttonPanel, "Start",
160: new ActionListener()
161: {
162: public void actionPerformed(ActionEvent event)
163: {
164: addBall();
165: }
166: });
167:
168: addButton(buttonPanel, "Close",
169: new ActionListener()
170: {
171: public void actionPerformed(ActionEvent event)
172: {
173: System.exit(0);
174: }
175: });
176: add(buttonPanel, BorderLayout.SOUTH);
177: }
178:
179: /**
180: Adds a button to a container.
181: @param c the container
182: @param title the button title
183: @param listener the action listener for the button
184: */
185: public void addButton(Container c, String title, ActionListener listener)
186: {
187: JButton button = new JButton(title);
188: c.add(button);
189: button.addActionListener(listener);
190: }
191:
192: /**
193: Adds a bouncing ball to the canvas and starts a thread
194: to make it bounce
195: */
196: public void addBall()
197: {
198: Ball b = new Ball();
199: panel.add(b);
200: Runnable r = new BallRunnable(b, panel);
201: Thread t = new Thread(r);
202: t.start();
203: }
204:
205: private BallPanel panel;
206: public static final int DEFAULT_WIDTH = 450;
207: public static final int DEFAULT_HEIGHT = 350;
208: public static final int STEPS = 1000;
209: public static final int DELAY = 3;
210: }
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