关键侦听器由于某种原因无法正常工作 [英] key listener not working for some reason

问题描述

我编写了这段代码，当您启动它时，它会显示一个图像，然后在您按向左或向右键时在其他两个图像之间进行更改，但是由于某种原因，它没有从键盘读取输入，我尝试使用mouseListener并成功了，这是代码:

i made this code that when you start it it's suposed to show you an image and then change it between other two images when you press the left or right key, but for some reason it isn't reading the input from the keyboard, i tryed to use a mouseListener and it worked, this is the code:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Implementary extends JFrame
{
    private static final long serialVersionUID = 1L;
    public Dimension d;
    public static ImageIcon Im = new ImageIcon(Implementary.class.getResource("death.png"));
    public static ImageIcon Imc = new ImageIcon(Implementary.class.getResource("right.png"));
    public static ImageIcon I = new ImageIcon(Implementary.class.getResource("left.png"));
    public static Image Img = Im.getImage();
    public static int x = 10;
    public static int y = 10;

    public Implementary()
    {
        super("hue");
        int x1 = (int) Toolkit.getDefaultToolkit().getScreenSize().getWidth();
        int y1 = (int) Toolkit.getDefaultToolkit().getScreenSize().getHeight();
        d = new Dimension(x1, y1 - 45);
        this.setSize(d);
        this.setLocationRelativeTo(null);
        Panel p = new Panel();
        p.addKeyListener(new KeyListener()
        {
            @Override
            public void keyTyped(KeyEvent e)
            {
                keyPressed(e);
            }

            @Override
            public void keyPressed(KeyEvent e)
            {
                int k = e.getKeyCode();
                if (k == KeyEvent.VK_LEFT)
                {
                    Img = I.getImage();
                    repaint();
                    System.out.println(3);
                }
                else
                {
                    Img = Imc.getImage();
                    repaint();
                    System.out.println(2);
                }
                System.out.println(1);
            }

            @Override
            public void keyReleased(KeyEvent e)
            {
                keyPressed(e);
            }
        });
        this.add(p);
    }

    static class Panel extends JPanel
    {
        private static final long serialVersionUID = 1L;

        public void paintComponent(Graphics g)
        {
            super.paintComponent(g);
            this.setBackground(Color.cyan);
            g.drawImage(Img, x, y, null);
        }
    }
}

这是主要的类:

public class Yo
{
    public static void main(String args[])
    {
        Implementary imp = new Implementary();
        imp.setVisible(true);
    }
}

推荐答案

将KeyListener添加到整个JFrame可以解决问题. 由于您的JPanel无法选择/集中显示，因此不会收到击键.

Adding the KeyListener to the whole JFrame could do the trick. As your JPanel cannot be selected/focused it doesn't receive keystrokes.

更改

p.addKeyListener(new KeyListener()

到

this.addKeyListener(new KeyListener()

为我工作.

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