出于某种原因,我的KeyListener只是没有响应KeyPressed事件.

如果重要,我在Ubuntu 12.04上.每按一次键就应该打印“按键”,但不是.

这是代码：

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

public class DisplayPanel extends JPanel
{
    private Tile[][] tiles;
    private Creature[] creatures;
    private Dungeon dungeon;
    private Player player;

    public DisplayPanel(Dungeon dungeon, Tile[][] tiles, Creature[] creatures, Player player)
    {
        this.tiles = tiles;
        this.creatures = creatures;
        this.dungeon = dungeon;
        this.player = player;
        addKeyListener(new DungeonKeyListener());
        requestFocus();
    }

    protected void paintComponent(Graphics g)
    {
        int maximum = (getWidth() < getHeight()) ? getWidth() : getHeight();
        for (Tile[] row : tiles)
        {
            for (Tile tile : row)
            {
                if (tile != null && tile instanceof Tile)
                {
                    tile.draw(g, maximum/tiles.length, maximum/tiles[0].length);
                }
            }
        }
        for (Creature creature : creatures)
        {
            if (creature != null && creature instanceof Creature)
            {
                creature.draw(g, maximum/tiles.length, maximum/tiles[0].length);
            }
        }

        if (player != null && player instanceof Player)
        {
            player.draw(g, maximum/tiles.length, maximum/tiles[0].length);
        }
    }

    private class DungeonKeyListener extends KeyAdapter
    {
        public void keyReleased(KeyEvent e)
        {
            System.out.println("Key pressed!");
            dungeon.press(e.getKeyCode());
            repaint();
        }
    }
}

解决方法:

>调用super.paintComponent(与您的问题无关,但稍后会解决一些问题)
>使组件“可聚焦” – Component#setFocusable
>在KeyListener上使用key bindings
>在Component#requestFocus上使用Component#requestFocusInWindow …

来自Java Docs

Because the focus behavior of this method is platform-dependent,
developers are strongly encouraged to use requestFocusInWindow when
possible