为什么keyListener不起作用? [英] Why isn't the keyListener working?

问题描述

这是我制作的乒乓球游戏，但是唯一不起作用的是桨在运动.我不确定如何使键盘与程序一起使用.这是主要游戏的代码:

This is a pong game I made, but the only thing that is not working is the paddles moving. I am not sure how to make the keyboard work with the program. Here is the code for the main game:

//Project: A program where you play the game pong

//This module defines the properties of the user interface

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;


public class pongframe extends JFrame
{
    private JLabel playerlefttitle;
    private JLabel playerrighttitle;
    private JLabel speedtitle;
    private JTextField speedfield;
    private JTextField playerleftscorefield;
    private JTextField playerrightscorefield;
    private JButton newgame;
    private JButton gobutton;
    private JButton pausebutton;
    private JButton quitgame;
    private Timer systemclock;
    private Timer paddleclock;
    private String speedstring;
    private int speed;
    private int leng = 10;
    private int delayinterval;
    private float millisecondpersecond = 1000.0f;
    private boolean win = false;
    private int playerleftscore=0;
    private int playerrightscore=0;
    private boolean rightup = false;
    private boolean rightdown = false;
    private boolean leftup = false;
    private boolean leftdown = false;
    private boolean barhit = true;
    private double direction=0;
    private pongoperations graphicalpanel;
    private Clockhandlerclass clockhandler;
    private PaddleClockHandlerClass paddleclockhandler;
    private PaddleHandlerClass paddlehandler;

    public pongframe()
    {
        super("Pong");
        JPanel panel1 = new JPanel(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        graphicalpanel = new pongoperations();
        graphicalpanel.setBackground(Color.GREEN);
        add(graphicalpanel, BorderLayout.CENTER);

        add(panel1, BorderLayout.SOUTH);
        c.insets = new Insets(0,0,10,10);
        newgame = new JButton("New");
        c.gridx = 0;
        c.gridy = 1;
        panel1.add(newgame, c);
        speedtitle = new JLabel("Speed");
        c.gridx = 1;
        c.gridy = 0;
        panel1.add(speedtitle, c);
        speedfield = new JTextField(3);
        c.gridx = 1;
        c.gridy = 1;
        panel1.add(speedfield, c);
        quitgame = new JButton("Quit");
        c.gridx = 2;
        c.gridy = 1;
        panel1.add(quitgame, c);
        playerlefttitle = new JLabel("Player Left");
        c.gridx = 0;
        c.gridy = 3;
        panel1.add(playerlefttitle, c);
        playerrighttitle = new JLabel("Player Right");
        c.gridx = 3;
        c.gridy = 3;
        panel1.add(playerrighttitle, c);
        playerleftscorefield = new JTextField(2);
        playerleftscorefield.setEditable(false);
        c.gridx = 0;
        c.gridy = 4;
        panel1.add(playerleftscorefield, c);
        gobutton = new JButton("Go");
        c.gridx = 1;
        c.gridy = 4;
        panel1.add(gobutton, c);
        pausebutton = new JButton("Pause");
        c.gridx = 2;
        c.gridy = 4;
        panel1.add(pausebutton, c);
        playerrightscorefield = new JTextField(2);
        playerrightscorefield.setEditable(false);
        c.gridx = 3;
        c.gridy = 4;
        panel1.add(playerrightscorefield, c);
        buttonhandler myhandler = new buttonhandler();
        newgame.addActionListener(myhandler);
        gobutton.addActionListener(myhandler);
        pausebutton.addActionListener(myhandler);
        quitgame.addActionListener(myhandler);
        clockhandler = new Clockhandlerclass();
        paddleclockhandler = new PaddleClockHandlerClass();
        paddlehandler = new PaddleHandlerClass();
    }
    private class buttonhandler implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            graphicalpanel.reset();
            if(event.getSource() == newgame)
            {
                speedfield.setText("");
                playerleftscore = 0;
                playerrightscore = 0;
                playerleftscorefield.setText("0");
                playerrightscorefield.setText("0");
                graphicalpanel.reset();
                graphicalpanel.repaint();
                gobutton.setEnabled(true);
                speedfield.setEditable(true);
                newgame.setEnabled(false);
            }
            else if(event.getSource() == gobutton)
            {
                speedstring = speedfield.getText();
                leng = speedstring.length();
                if(leng == 0)
                    speed = 0;
                else 
                {
                    speed = Integer.parseInt(speedstring);
                    gobutton.setEnabled(false);
                    speedfield.setEditable(false);
                }
                newgame.setEnabled(false);
                delayinterval = (int)Math.floor(millisecondpersecond/speed + 0.5f);
                systemclock = new Timer(delayinterval, clockhandler);
                systemclock.start();
                paddleclock = new Timer(delayinterval, paddleclockhandler);
                paddleclock.start();
            }
            else if(event.getSource() == pausebutton)
            {
                gobutton.setEnabled(true);
                newgame.setEnabled(true);
                systemclock.stop();
            }
            else if(event.getSource() == quitgame)
            {
                System.exit(0);
            }
            else
                System.out.println("Unkown error");
        }
    }
    private class Clockhandlerclass implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            if(event.getSource() == systemclock)
            {
                graphicalpanel.grabFocus();
                graphicalpanel.moveball(speed,delayinterval, direction, barhit);
                direction = graphicalpanel.changedirection(direction);

                if(win == false)
                {
                    barhit = graphicalpanel.barhits(barhit);
                    graphicalpanel.repaint();
                    win = graphicalpanel.winner();
                    playerleftscore = graphicalpanel.playerleftwin(playerleftscore);
                    playerrightscore = graphicalpanel.playerrightwin(playerrightscore);
                    playerleftscorefield.setText(Integer.toString(playerleftscore));
                    playerrightscorefield.setText(Integer.toString(playerrightscore));
                }
                else if(win == true)
                {
                    graphicalpanel.reset();
                    win = false;
                    systemclock.restart();
                    if(playerleftscore == 10)
                    {
                        newgame.setEnabled(true);
                        systemclock.stop();
                    }
                    else if(playerrightscore == 10)
                    {
                        newgame.setEnabled(true);
                        systemclock.stop();
                    }
                    graphicalpanel.repaint();
                }   
            }
            else
                System.out.printf("%s\n", "There is a bug in the clock.");
        }
    }
    private class PaddleClockHandlerClass implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            if(event.getSource() == paddleclock)
            {
                graphicalpanel.moveplayer1(rightup, rightdown);
                graphicalpanel.moveplayer2(leftup, leftdown);
                graphicalpanel.repaint();
            }
        }
    }
    private class PaddleHandlerClass implements KeyListener
    {
        public void keyTyped(KeyEvent event)
        {
        }
        public void keyPressed(KeyEvent event)
        {
            if(event.getKeyCode() == KeyEvent.VK_UP)
            {
                rightup = true;
                System.out.println("Up");
            }
            else if(event.getKeyCode() == KeyEvent.VK_DOWN)
                rightdown = true;
            if(event.getKeyCode() == KeyEvent.VK_W)
                leftup = true;
            else if(event.getKeyCode() == KeyEvent.VK_S)
                leftdown = true;
        }
        public void keyReleased(KeyEvent event)
        {
            if(event.getKeyCode() == KeyEvent.VK_UP)
                rightup = false;
            else if(event.getKeyCode() == KeyEvent.VK_DOWN)
                rightdown = false;
            if(event.getKeyCode() == KeyEvent.VK_W)
                leftup = false;
            else if(event.getKeyCode() == KeyEvent.VK_S)
                leftdown = false;
        }
    }
}   

下面的代码是我在游戏中使用的功能:

This next bit of code are the functions that I am using for the game:

//Project: A program where you play the game pong

//This module contains the graphics and algorithms used by this project.

import java.awt.Graphics;
import javax.swing.JPanel;
import java.awt.Color;

public class pongoperations extends JPanel
{
    int widthofgraphicalarea;
    int heightofgraphicalarea;
    final int ballradius = 8;
    int ballxcoordinate;
    double ballycoordinate;
    int paddle1xcoordinate;
    int paddle1ycoordinate;
    int paddle2xcoordinate;
    int paddle2ycoordinate;

    public void paintComponent(Graphics graphicarea)
    {//function to paint the area
        super.paintComponent(graphicarea);
        this.setBackground(Color.GREEN);
        widthofgraphicalarea = getWidth();
        heightofgraphicalarea = getHeight();
        //create paddle 1
        graphicarea.setColor(Color.BLUE);
        graphicarea.fillRect(paddle1xcoordinate, paddle1ycoordinate, 10, 50);
        //create paddle 2
        graphicarea.setColor(Color.RED);
        graphicarea.fillRect(paddle2xcoordinate, paddle2ycoordinate, 10, 50);
        //Give the ball a white color
        graphicarea.setColor(Color.WHITE);
        //The 3rd and 4th parameters below represent the diameter of the ball.
        graphicarea.fillOval(ballxcoordinate,(int)ballycoordinate,2*ballradius,2*ballradius);
    }//End of method paintComponent
    public void moveplayer1(boolean rightup, boolean rightdown)
    {
        if(rightup == true)
        paddle1ycoordinate -= 5;
        else if(rightdown == true)
        paddle1ycoordinate += 5;
        positionPlayer1(paddle1xcoordinate, paddle1ycoordinate);
    }
    public void moveplayer2(boolean leftup, boolean leftdown)
    {
        if(leftup == true)
        paddle2ycoordinate -= 5;
        else if(leftdown == true)
        paddle2ycoordinate += 5;
        positionPlayer2(paddle2xcoordinate, paddle2ycoordinate);
    }
    public void positionPlayer1(int x, int y)
    {
        this.paddle1xcoordinate = x;
        this.paddle1ycoordinate = y;
        repaint();
    }
    public void positionPlayer2(int x, int y)
    {
        this.paddle2xcoordinate = x;
        this.paddle2ycoordinate = y;
        repaint();
    }
    public void moveball(int speed, int delayinterval, double direction, boolean barhit)
    {
        if(barhit == true)
            ballxcoordinate+=1;
        else if(barhit == false)
            ballxcoordinate-=1;
        if(direction > 0)
            ballycoordinate = ballycoordinate + (double)Math.sin(Math.toRadians(direction));
        else if(direction < 0)
            ballycoordinate = ballycoordinate + (double)Math.sin(Math.toRadians(direction));
    }
    public boolean barhits(boolean barhit)
    {
        if(ballxcoordinate == paddle1xcoordinate+10 && (ballycoordinate >= paddle1ycoordinate && ballycoordinate <= paddle1ycoordinate+50))
            barhit = true;
        else if(ballxcoordinate+2*ballradius == paddle2xcoordinate && (ballycoordinate+2*ballradius >= paddle2ycoordinate && ballycoordinate+2*ballradius <= paddle2ycoordinate+50))
            barhit = false;
        return barhit;
    }
    public boolean winner()
    {
        if(ballxcoordinate+2*ballradius >= widthofgraphicalarea)
            return true;
        else if(ballxcoordinate+2*ballradius <= 16)
            return true;

        return false;
    }
    public int playerleftwin(int playerleftscore)
    {
        if(ballxcoordinate+2*ballradius >= widthofgraphicalarea)
            playerleftscore+=1;

        return playerleftscore;
    }
    public int playerrightwin(int playerrightscore)
    {
        if(ballxcoordinate+2*ballradius <= 16)
            playerrightscore+=1;

        return playerrightscore;
    }
    public double changedirection(double direction)
    {//function to change the direction of the ball to bounce of walls
        if((int)ballycoordinate+2*ballradius >= heightofgraphicalarea || (int)ballycoordinate+2*ballradius < 16)
            direction = -direction;
        return direction;
    }
    public void reset()
    {//reset the ball at middle of left side
        ballxcoordinate = widthofgraphicalarea/2 - ballradius;
        ballycoordinate = heightofgraphicalarea/2 - ballradius;
        paddle1xcoordinate = 10;
        paddle1ycoordinate = heightofgraphicalarea/2-25;
        paddle2xcoordinate = widthofgraphicalarea-20;
        paddle2ycoordinate = heightofgraphicalarea/2-25;
    }
}

请有人帮助.预先感谢.

Please someone help. Thanks in advance.

另一个可以帮助的问题是，一旦完成，如何将其切换为applet形式?

Another question if you can help is once this is finished how do I switch this over to applet form?

推荐答案

• 请勿使用KeyListener Swing组件，请使用 KeyBindings .

  • Do not use a KeyListener Swing components use KeyBindings.

    不要不必要地扩展JFrame类

    Swing组件应在 Event Dispatch Thread

    Swing components should be created on Event Dispatch Thread

    要设置应用程序的大小(在JFrame上没有setSize(..)调用)，请在添加组件按钮等时使用适当的LayoutManager(这样做)，并在paintComponent中进行绘制时覆盖JPanel 并返回适合所有工程图的适当大小，而不是在将其设置为可见之前调用JFrame上的pack()

    To set the size of your app (without setSize(..) call on JFrame) use appropiate LayoutManager when adding components buttons etc (which you do) and when drawing in paintComponent override JPanel getPreferredSize() and return an appropriate size which fits all drawings than call pack() on JFrame before setting it visible

    别忘了在JFrame上调用setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);，因此当按下 X 时，会按下 Event Dispatch Thread 和 Initial thread 退出，或应用程序仍将在后台运行.

    Dont forget to call setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); on JFrame so when X is pressed the Event Dispatch Thread and Initial thread are exited, or app will remain running in background.

    但是要解决您的问题，请在paddlehandler = new PaddleHandlerClass();之后添加:

    But to solve your problem after paddlehandler = new PaddleHandlerClass(); add:

      graphicalpanel.addKeyListener(paddlehandler);
    

    问题是您永远不会将KeyListener添加到任何要监听事件的组件中.

    the problem is you never added the KeyListener to any Component to listen for events.

    正确的解决方案是KeyBindings，它会像这样更改您的PaddleHandlerClass:

    The proper solution would be KeyBindings which would change your PaddleHandlerClass like this:

    private class PaddleHandlerClass {
    
        public PaddleHandlerClass(JComponent jc) {
    
            jc.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("UP"), "up");
            jc.getActionMap().put("up", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent ae) {
                    rightup = true;
                    System.out.println("Up");
                }
            });
            jc.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("released UP"), "rel up");
            jc.getActionMap().put("rel up", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent ae) {
                    rightup = false;
                }
            });
        }
    
    }
    

    而不是简单地创建paddleHandler并传递JPanel的实例，我们想要获取哪些键:

    than simply create the paddleHandler and pass instance of JPanel which keys we want to get:

    paddlehandler = new PaddleHandlerClass(graphicalpanel);
    

    这篇关于为什么keyListener不起作用?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！