问题
Trying to make pong in java but can't move both paddles at once. You can move one or the other but not both at the same time. Do I need to create 2 threads with 2 different pannels?
Here is where I am specifying the key events
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_A || e.getKeyCode() == KeyEvent.VK_S || e.getKeyCode() == KeyEvent.VK_QUOTE || e.getKeyCode() == KeyEvent.VK_SEMICOLON){
if(e.getKeyCode() == KeyEvent.VK_A){
y-=10;
}
if(e.getKeyCode() == KeyEvent.VK_S){
y+=10;
}
if(e.getKeyCode() == KeyEvent.VK_QUOTE){
ytwo-=10;
}
if(e.getKeyCode() == KeyEvent.VK_SEMICOLON){
ytwo+=10;
}
}
}
Here is the full code
import java.awt.Color;
import java.awt.Event;
import java.awt.Graphics;
import java.util.Random;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Pong extends JFrame implements ActionListener{
//implement constants
PongPanel pongPanel = new PongPanel();
//JFrame pong x and y coordinates
static final int jfpX = 150;
static final int jfpY = 20;
// JFrame pong width and height
static final int jfpW = 800;
static final int jfpH = 600;
Thread thrd;
public static void main(String[] args) {
Pong jfp = new Pong();
jfp.setVisible(true);
}
public Pong(){
setBounds(jfpX,jfpY,jfpW,jfpH);
setTitle("Pong");
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setBackground(Color.black);
add(pongPanel);
addKeyListener(pongPanel);
thrd = new Thread (pongPanel);
thrd.start();
}
public void actionPerformed(ActionEvent e) {
}
}
class PongPanel extends JPanel implements Runnable, KeyListener{
Random random = new Random();
static final int jpW = 800;
static final int jpH = 600;
int paddleStart = (jpH/2)-35;
int paddleStarttwo = (jpH/2)-35;
int ballStartX = (jpW/2)-20;
int ballStartY = (jpH/2)-20;
int ytwo,x,y;
int ballD = 30;
int paddleW1 = 20;
int paddleH1 = 100;
int paddleW2 = 20;
int paddleH2 = 100;
int min = -2;
int max = 2;
int randomBallx, randomBally;
// int randomBallx = random.nextInt(max-min+1)+min;
// int randomBally = random.nextInt(max-min+1)+min;
int rand1 = random.nextInt(2-1 + 1)+1; // random for function to determine ballx and bally
int rand2 = random.nextInt(2-1+2)+1;
int dx = 4;
int dy = 4; //direction of y
public void ballNotZero(){// makes sure the ball doesnt go straight up and down
if (randomBallx ==0){
randomBallx = random.nextInt(max-min+1)+min;
}
if(randomBally == 0){
randomBally=random.nextInt(max-min+1)+min;
}
// if(rand1 ==1){
// randomBallx=-1;
// }
// if(rand1 ==2){
// randomBallx=1;
// }
// if(rand2 ==1){
// randomBally =-1;
// }
// if(rand2==2){
// randomBally = 1;
// }
}
public PongPanel(){
}
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Color ball;
Color paddleOne;
Color paddleTwo;
ball = new Color(255,0,255);
paddleOne = new Color(255,0,0);
paddleTwo = new Color(0,0,255);
g.setColor(ball);
g.fillOval(ballStartX+randomBallx,ballStartY+randomBally,ballD,ballD);
g.setColor(paddleOne);
g.fillRect(20,paddleStart+y,paddleW1,paddleH1);
g.setColor(paddleTwo);
g.fillRect(760,paddleStarttwo+ytwo,paddleW2,paddleH2);
}
public void run() {
while(true){
ballNotZero();
detectPaddle();
randomBall();
ballMove();
repaint();
try {Thread.sleep(75); } catch(Exception e){
};
}
}
public static boolean intervallContains(int low, int high, int n) { //determines if something is in a certain range
return n >= low && n <= high;
}
public void detectPaddle(){ //determines if ball is close enough to paddle for detection
int withinY = (paddleStart+y) -(ballStartY+randomBally);
int withinY1 = (paddleStarttwo+ytwo)-(ballStartY+randomBally);
if (ballStartX+randomBallx <=20 && intervallContains(-50,50,withinY)){
dx = -dx;
}
if(ballStartX+randomBallx >=760 && intervallContains(-50,50,withinY1)){
dx = -dx;
}
}
public void randomBall(){
if(randomBallx >=0 ){
randomBallx+=dx;
}
if(randomBallx<0){
randomBallx-=dx;
}
if(randomBally>=0){
randomBally+=dy;
}
if(randomBally<0){
randomBally-=dy;
}
// randomBallx+=randomBallx;
// randomBally+=randomBally;
}
public void ballMove(){
if(ballStartY+randomBally > jpH-60){
dy= -dy;
}
if(ballStartY+randomBally <0){
dy = -dy;
}
}
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_A || e.getKeyCode() == KeyEvent.VK_S || e.getKeyCode() == KeyEvent.VK_QUOTE || e.getKeyCode() == KeyEvent.VK_SEMICOLON){
if(e.getKeyCode() == KeyEvent.VK_A){
y-=10;
}
if(e.getKeyCode() == KeyEvent.VK_S){
y+=10;
}
if(e.getKeyCode() == KeyEvent.VK_QUOTE){
ytwo-=10;
}
if(e.getKeyCode() == KeyEvent.VK_SEMICOLON){
ytwo+=10;
}
}
}
public void keyTyped(KeyEvent e) {
}
@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
}
回答1:
- Don't use
while (true)but rather a Swing timer. - Don't use KeyListeners but rather Key Bindings.
- Consider turning on a Swing Timer (which can act as your "background thread") that moves one paddle when the bindings detect the correct key has been pressed,
- and stopping the timer that moves the paddle when the same key is released.
- Same for the other paddle but of course having its actions respond to a bindings of a different pair of keys.
- When attempting to get something like this working, try to get it working in a very simple program first, one without all the other junk required for your main program, but one which will allow you to test and prove your concept. Then if you get things working in your small program, great, you add the functionality to your main program. And if your small program code doesn't work and you need our help, you can post the small self-contained program here (an sscce) for us to test and modify.
来源：https://stackoverflow.com/questions/16025533/java-pong-cant-move-both-paddles-at-once