问题
I am a new coder. I am having trouble adding a start and stop button for this piece of example code that i am working off. I'm sure i have to mess with with Thread.sleep(10); in the game class. This code starts the game when the program is run. is there a way i could add start button to start the thread. I have created j button already. Thanks.
Game Class
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
@SuppressWarnings("serial")
public class Game extends JPanel {
Ball ball = new Ball(this);
Racquet racquet = new Racquet(this);
public Game() {
addKeyListener(new KeyListener() {
@Override
public void keyTyped(KeyEvent e) {
}
@Override
public void keyReleased(KeyEvent e) {
racquet.keyReleased(e);
}
@Override
public void keyPressed(KeyEvent e) {
racquet.keyPressed(e);
}
});
setFocusable(true);
}
private void move() {
ball.move();
racquet.move();
}
@Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
ball.paint(g2d);
racquet.paint(g2d);
}
public void gameOver() {
JOptionPane.showMessageDialog(this, "Game Over", "Game Over", JOptionPane.YES_NO_OPTION);
System.exit(ABORT);
}
public static void main(String[] args) throws InterruptedException {
JFrame frame = new JFrame("Mini Tennis");
Game game = new Game();
frame.add(game);
frame.setSize(300, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
while (true) {
game.move();
game.repaint();
Thread.sleep(10);
}
}
}
Ball Class
import java.awt.Graphics2D;
import java.awt.Rectangle;
public class Ball {
private static final int DIAMETER = 30;
int x = 0;
int y = 0;
int xa = 1;
int ya = 1;
private Game game;
public Ball(Game game) {
this.game= game;
}
void move() {
if (x + xa < 0)
xa = 1;
if (x + xa > game.getWidth() - DIAMETER)
xa = -1;
if (y + ya < 0)
ya = 1;
if (y + ya > game.getHeight() - DIAMETER)
game.gameOver();
if (collision()){
ya = -1;
y = game.racquet.getTopY() - DIAMETER;
}
x = x + xa;
y = y + ya;
}
private boolean collision() {
return game.racquet.getBounds().intersects(getBounds());
}
public void paint(Graphics2D g) {
g.fillOval(x, y, DIAMETER, DIAMETER);
}
public Rectangle getBounds() {
return new Rectangle(x, y, DIAMETER, DIAMETER);
}
}
Racquet Class
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
public class Racquet {
private static final int Y = 330;
private static final int WIDTH = 60;
private static final int HEIGHT = 10;
int x = 0;
int xa = 0;
private Game game;
public Racquet(Game game) {
this.game = game;
}
public void move() {
if (x + xa > 0 && x + xa < game.getWidth() - WIDTH)
x = x + xa;
}
public void paint(Graphics2D g) {
g.fillRect(x, Y, WIDTH, HEIGHT);
}
public void keyReleased(KeyEvent e) {
xa = 0;
}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT)
xa = -1;
if (e.getKeyCode() == KeyEvent.VK_RIGHT)
xa = 1;
}
public Rectangle getBounds() {
return new Rectangle(x, Y, WIDTH, HEIGHT);
}
public int getTopY() {
return Y;
}
}
回答1:
This is an mcve demonstrating the structure outlined in Hovercraft Full Of Eels comment :
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.ActionListener;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class AnimationUsingTimer {
private Timer timer;
AnimationUsingTimer() {
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
AnimationPanel animationPanel = new AnimationPanel();
window.add(animationPanel);
JButton start = new JButton("Start");
start.addActionListener(e -> animationPanel.start());
window.add(start, BorderLayout.PAGE_START);
JButton stop = new JButton("Stop");
stop.addActionListener(e -> animationPanel.stop());
window.add(stop, BorderLayout.PAGE_END);
window.pack();
window.setVisible(true);
}
class AnimationPanel extends JPanel{
private BufferedImage img;
private Area ball, walls;
private final static int W = 450, H = 300, DIAMETER = 20;
private int x = W/2, y = H/2, xDelta = 3, yDelta = 2;
AnimationPanel() {
img = new BufferedImage(W, H, BufferedImage.TYPE_INT_RGB);
JLabel imageLabel = new JLabel(new ImageIcon(img));
add(imageLabel);
walls = new Area(new Rectangle(0,0,W,H));
ActionListener animate = e -> {
animate();
repaint();
};
timer = new Timer(50, animate);
}
public void animate() {
x+=xDelta; y+=yDelta;
ball = new Area(new Ellipse2D.Double(x, y, DIAMETER, DIAMETER));
if (checkCollision(ball,walls)) {
if ( x+DIAMETER>img.getWidth() || x<0 ) {
xDelta *= -1;
}
if(y+DIAMETER>img.getHeight() || y<0 ) {
yDelta *= -1;
}
}
}
@Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2D = img.createGraphics();
g2D.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2D.setColor(Color.CYAN);
g2D.fillRect(0, 0, img.getWidth(), img.getHeight());
if(ball != null){
g2D.setColor(Color.RED);
g2D.fill(ball);
}
g2D.dispose();
}
void start(){
timer.start();
}
void stop(){
timer.stop();
}
private boolean checkCollision(Area area1, Area area2) {
return area1.getBounds().intersects(area2.getBounds());
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new AnimationUsingTimer());
}
}
来源：https://stackoverflow.com/questions/53699325/adding-start-stop-reset-button-to-simple-java-game