java-只需按一下键即可连续运动？

我正在尝试用Java编写一个程序,该程序涉及使对象从一次按键操作中不断移动.想一想吃豆子,在其中按下一次,吃豆子继续上升直到您按下另一个键.如果可能的话,我想保持代码简单.我的原始动作(一键按下=一动作)是这样的：

public class AL extends KeyAdapter {
    public void keyPressed(KeyEvent e){
        int keyCode = e.getKeyCode();
        if(keyCode == e.VK_A){
            x -= 5;
        }
        if(keyCode == e.VK_D){
            x += 5;
        }
        if(keyCode == e.VK_W){
            y -= 5;
        }
        if(keyCode == e.VK_S){
            y += 5;
        }

    }

值中的x和y是椭圆的位置.这完美地工作了,但是我希望它只按一次键就可以继续运动,而不必按住它来保持运动.我尝试了一个带有布尔参数的while循环,该布尔参数在true时移动,而在false时不移动,但是一旦激活该循环,它就会冻结程序.这是这段代码的示例：

public void keyPressed(KeyEvent e){
        int keyCode = e.getKeyCode();
        if(keyCode == e.VK_LEFT && moveL==false){
           moveL=true;
           moveR=false;
           moveU=false;
           moveD=false;
           while(moveL){
            x--;
            }
        }

请帮我解决这个问题,我已经尝试了好几天了.感谢您提供的任何帮助.谢谢.

解决方法:

基本概念围绕着“增量”或“变化”值的思想.然后,通过将该状态值递增或递减,将其应用于要更改的状态.

由于Swing的性质,您不能阻止“事件调度线程”,否则最终将阻止处理传入事件(例如绘画和按键事件).

同样,除了EDT之外,您永远不要尝试从任何线程更新任何UI组件(或可能影响UI的状态变量).

尽管有一些技巧可以满足这些要求,但最简单的方法是使用javax.swing.Timer,它会在EDT中定期触发一个actionPerformed事件.

发生这种情况时,您可以按规定的数量“更新”所有元素并重新粉刷屏幕.

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class PacManTest {

    public static void main(String[] args) {
        new PacManTest();
    }

    public PacManTest() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new MazePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class PacMan {

        private int x;
        private int y;

        private int deltaX;
        private int deltaY;

        private BufferedImage sprite;

        public PacMan() {
            try {
                sprite = ImageIO.read(new File("PacMan.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        public void move(int x, int y) {
            deltaX = x;
            deltaY = y;
        }

        public void update(MazePane pane) {
            x += deltaX;
            y += deltaY;
            if (x + sprite.getWidth() > pane.getWidth()) {
                x = pane.getWidth() - sprite.getWidth();
            } else if (x < 0) {
                x = 0;
            }
            if (y + sprite.getHeight() > pane.getHeight()) {
                y = pane.getHeight() - sprite.getHeight();
            } else if (y < 0) {
                y = 0;
            }
        }

        public void paint(MazePane pane, Graphics2D g2d) {
            Graphics2D g = (Graphics2D) g2d.create();

            float angle = 0;
            if (deltaX != 0) {
                angle = deltaX > 0 ? 0 : 180;
            } else if (deltaY != 0) {
                angle = deltaY > 0 ? 90 : 270;                
            }
            AffineTransform t = new AffineTransform();
            t.translate(x, y);
            t.rotate(Math.toRadians(angle), sprite.getWidth() / 2, sprite.getHeight() / 2);
            g.setTransform(t);
            g.drawImage(sprite, 0, 0, pane);
            g.dispose();
        }

    }

    public class MazePane extends JPanel {

        private PacMan pacMan;
        public MazePane() {
            pacMan = new PacMan();
            Timer timer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    pacMan.update(MazePane.this);
                    repaint();
                }
            });
            timer.start();
            InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
            ActionMap am = getActionMap();

            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "left");
            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "right");
            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "up");
            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "down");

            am.put("left", new MoveAction(pacMan, -4, 0));
            am.put("right", new MoveAction(pacMan, 4, 0));
            am.put("up", new MoveAction(pacMan, 0, -4));
            am.put("down", new MoveAction(pacMan, 0, 4));
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            pacMan.paint(this, g2d);
            g2d.dispose();
        }

        public class MoveAction extends AbstractAction {

            private int deltaX;
            private int deltaY;
            private PacMan pacMan;

            public MoveAction(PacMan pacMan, int deltaX, int deltaY) {
                this.deltaX = deltaX;
                this.deltaY = deltaY;
                this.pacMan = pacMan;
            }

            @Override
            public void actionPerformed(ActionEvent e) {
                pacMan.move(deltaX, deltaY);
            }

        }        
    }
}

我还建议您花一些时间来学习Key Bindings,KeyListener会遇到焦点问题,这些键绑定能够解决…

标签：java,keypress,game-physics
来源： https://codeday.me/bug/20191009/1880209.html