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我目前正在嘗試用Java構建一個基本的Pong遊戲，並且我在兩件事情上遇到困難。首先是我的球拍應該上下移動，但是一旦他們到達球拍邊緣，球拍就會完全凍結。我不明白爲什麼。接下來，我不確定如何使用Timer或Thread.sleep在每次得分後立即暫停遊戲。一旦其中一名球員得分，我希望比賽將球送回中鋒並等待大約3秒鐘，然後球再次移動以開始下一個點。任何幫助都會很棒。謝謝！在Java Pong遊戲中KeyListener和Timer的問題
這裏是我的代碼
傍類
import java.awt.*;
import javax.swing.*;
public class Pong extends JFrame{
public static final int appWIDTH = 500; //width of jframe
public static final int appHEIGHT = 500; //height of jframe
public final int rWIDTH = 20; //width of racket
public final int rHEIGHT = 60; //height of racket
PongPanel panel; //Jpanel to be added
/*
* constructor for a Pong object
*/
public Pong() {
setSize(appWIDTH, appHEIGHT);
setTitle("PONG");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setBackground(Color.BLACK);
}
/*
* Starts the application
*/
public void start() {
panel = new PongPanel(this);
add(panel);
addKeyListener(panel);
setVisible(true);
setFocusable(true);
}
//Returns a PongPanel
public PongPanel getPanel() {
return panel;
}
public static void main(String[] args) {
Pong game = new Pong();
game.start();
}
}
面板類
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class PongPanel extends JPanel implements KeyListener {
private Pong game;
private Ball ball;
private Racket p1, p2;
private int score1, score2;
Timer timer;
/*
* Constructor for a PongPanel which is a JPanel that holds two rackets and a ball
*/
public PongPanel(Pong game) {
this.game = game;
p1 = new Racket(game, KeyEvent.VK_W, KeyEvent.VK_S, 0);
p2 = new Racket(game, KeyEvent.VK_UP, KeyEvent.VK_DOWN, game.getWidth() - game.rWIDTH);
ball = new Ball(game);
addKeyListener(this);
setFocusable(true);
setVisible(true);
}
/*
* Returns the Racket object associated with player 1
*/
public Racket getRacket1() {
return p1;
}
/*
* Returns the Racket object associated with player 2
*/
public Racket getRacket2() {
return p2;
}
//Increases score of the player indicated by the parameter
public void increaseScore(int playerNo) {
if(playerNo == 1)
score1++;
else
score2++;
}
//Returns the score of the player indicated by the parameter
public int getScore(int playerNo) {
if(playerNo == 1)
return score1;
else
return score2;
}
public void update() {
ball.hitBTS();
p1.move();
p2.move();
repaint();
}
public void keyPressed(KeyEvent ke) {
p1.kpressed(ke.getKeyCode());
p2.kpressed(ke.getKeyCode());
}
public void keyReleased(KeyEvent ke){
p1.krelease(ke.getKeyCode());
p2.krelease(ke.getKeyCode());
}
public void keyTyped(KeyEvent ke) {}
public void paintComponent(Graphics g) {
super.paintComponent(g);
ball.paint(g);
p1.paint(g);
p2.paint(g);
update();
}
}
球類
import java.awt.Graphics;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class Ball {
private JFrame frame = new JFrame();
private Pong game;
final int bWIDTH = 30; //ball width
final int bHEIGHT = 30; //ball height
private int xspeed = 1; //horizontal speed of the ball
private int yspeed = 1; //vertical speed of the ball
int x; //x-coordinate of the ball
int y; //y-coordinate of the ball
/*
* Constructor of a ball object. Sets the ball in the center of frame
*/
public Ball(Pong game) {
x = game.getWidth()/2 - (bWIDTH/2);
y = game.getHeight()/2 - (bHEIGHT/2);
this.game = game;
}
/*
* Checks whether the ball has hit the bottom or top of the frame
* or if it has reached the left or right edge (score)
*/
public void hitBTS() {
x += xspeed;
y += yspeed;
if((x + bWIDTH) > game.getWidth()) {
game.getPanel().increaseScore(1);
x = game.getWidth()/2 - (bWIDTH/2);
y = game.getHeight()/2 -(bHEIGHT/2);
}
else if(x < 0) {
game.getPanel().increaseScore(2);
x = game.getWidth()/2 - (bWIDTH/2);
y = game.getHeight()/2 -(bHEIGHT/2);
}
else if(y < 0 || (y > game.getHeight() + bHEIGHT)) {
yspeed = -yspeed;
}
checkScore();
checkCollision();
}
//Shows a dialog box indicating the winter if one player reaches
//a score of 3
public void checkScore() {
if(game.getPanel().getScore(1) == 3) {
JOptionPane.showMessageDialog(frame, "Player 1 wins");
}
else if(game.getPanel().getScore(2) == 3) {
JOptionPane.showMessageDialog(frame, "Player 2 wins");
}
}
//Checks if the ball has hit a racket
public void checkCollision() {
if(getBallBounds().intersects(game.getPanel().getRacket1().getBounds()) ||
getBallBounds().intersects(game.getPanel().getRacket2().getBounds())) {
xspeed = -xspeed;
}
}
public Rectangle getBallBounds() {
return new Rectangle(x, y, bWIDTH, bHEIGHT);
}
public void paint(Graphics g) {
g.fillRect(x, y, bWIDTH, bHEIGHT);
}
}
球拍類
import java.awt.*;
import java.awt.event.*;
public class Racket {
private Pong game;
private int yspeed = 0; //Number of pixels that the racket moves
int x; //x-coordinate of racket
int y; //y-coordinate of racket
int keyUp, keyDown; //key code associated with the key pressed
/*
* Constructor for a racket object. Racket receives a keycode and horizontal
* starting position.
*/
public Racket(Pong game, int keyUp, int keyDown, int x) {
this.game = game;
this.x = x;
this.keyUp = keyUp;
this.keyDown = keyDown;
y = game.getHeight()/2;
}
/*
* Indicates how the racket should move depending on its position.
*/
public void move() {
if(y > 0 && y < game.getHeight() - game.rHEIGHT)
y += yspeed;
else if(y <= 0)
y = y + 3;
else if(y == game.getHeight() - game.rHEIGHT)
y = y - 3;
}
/*
* If key has been pressed, the number of pixels the
* racket moves becomes positive or negative
*/
public void kpressed(int keyCode) {
if(keyCode == keyUp) {
yspeed = -3;
}
if(keyCode == keyDown)
yspeed = 3;
}
/*
* When the key is no longer being pressed, the
* racket stops moving.
*/
public void krelease(int keyCode) {
if(keyCode == keyUp)
yspeed = 0;
else if (keyCode == keyDown)
yspeed = 0;
}
public Rectangle getBounds() {
return new Rectangle(x, y, game.rWIDTH, game.rHEIGHT);
}
public void paint(Graphics g) {
g.fillRect(x, y, game.rWIDTH, game.rHEIGHT);
}
}
開始由具有看看[如何使用按鍵綁定（http://docs.oracle的.com/JavaSE的/教程/ uiswing /雜項/ keybinding.html）。關鍵事件不應直接修改UI的狀態或UI可能依賴的任何值，而應該簡單地設置一個標誌來指示哪些鍵當前處於活動狀態。使用Swing'Timer'或'Thread'作爲主要的「遊戲循環」，通過每個循環確定遊戲是否暫停，如果是，則什麼都不做，否則根據標誌更新UI狀態並重新計劃重畫 – MadProgrammer