addKeyListener() nie działa dla JPanel

Question

Próbuję stworzyć silnik gry. Zrobiłem klasę gry, ale błąd znajduje się w klasie KeyBoard. Tutaj zostawiam kod.

Class :: Gra

package transfer2pc.co.cc.game.tileengine; 

import java.awt.Graphics; 
import java.util.HashMap; 

import javax.swing.JPanel; 

import transfer2pc.co.cc.game.tileengine.input.KeyBoard; 

public abstract class Game extends JPanel implements Runnable { 

    /** 
    * 
    */ 
    private static final long serialVersionUID = 640206679500196209L; 

    HashMap<String, ?> maps = null; 

    KeyBoard keyBoard = null; 

    public Game(){ 
     super(); 
     keyBoard = new KeyBoard(this); 
     setKeyBoard(keyBoard); 
     Thread th = new Thread(this); 
     th.start(); 
    } 

    public void run(){ 
     while(true){ 
      repaint(); 
      try { 
       Thread.sleep(30); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

    @Override 
    public void paint(Graphics g){ 

    } 

    public void addMap(){ 

    } 

    public void setMap(){ 

    } 

    public abstract void keyPressed(int code); 

    public abstract void keyReleased(int code); 

    public abstract void keyTyped(int code); 

    public void setKeyBoard(KeyBoard key){ 
     addKeyListener(key); 
    } 

} 

Class :: KeyBoard

package transfer2pc.co.cc.game.tileengine.input; 

import java.awt.event.KeyAdapter; 
import java.awt.event.KeyEvent; 
import java.awt.event.KeyListener; 

import transfer2pc.co.cc.game.tileengine.Game; 

public class KeyBoard extends KeyAdapter implements KeyListener { 

    Game game = null; 

    public KeyBoard(Game gm){ 
     this.game = gm; 
    } 

    @Override 
    public void keyPressed(KeyEvent e) { 
     System.out.println("KeyPressed"); 
     game.keyPressed(e.getKeyCode()); 
    } 

    @Override 
    public void keyReleased(KeyEvent e) { 
     game.keyReleased(e.getKeyCode()); 
    } 

    @Override 
    public void keyTyped(KeyEvent e) { 
     game.keyTyped(e.getKeyCode()); 
    } 

    public static char getChar(int key){ 
     return (char)key; 
    } 

} 

Class :: KeyTest

package transfer2pc.co.cc.game.tileengine.test; 

import java.awt.Graphics; 

import javax.swing.JFrame; 

import transfer2pc.co.cc.game.tileengine.Game; 
import transfer2pc.co.cc.game.tileengine.input.KeyBoard; 

public class KeyTest extends Game { 

    /** 
    * 
    */ 
    private static final long serialVersionUID = 8557676950779023327L; 

    char pressed; 

    public KeyTest(){ 
     super(); 
     addKeyListener(new KeyBoard(this)); 
    } 

    @Override 
    public void keyPressed(int code) { 
     pressed = KeyBoard.getChar(code); 
    } 


    @Override 
    public void keyReleased(int code) { 

    } 


    @Override 
    public void keyTyped(int code) { 

    } 

    @Override 
    public void paint(Graphics g){ 
     g.drawString("You pressed: "+pressed, 20, 20); 
    } 

    public static void main(String[] args){ 
     JFrame frame = new JFrame("KeyTest"); 
     frame.setSize(640, 480); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setLocationRelativeTo(null); 
     frame.add(new KeyTest()); 
     frame.setVisible(true); 
    } 

} 

Ale błąd był nie było rzucony wyjątek i ISN wejście Czytałem. Czy ktokolwiek mógłby mi powiedzieć, jak to zrobić prawidłowo?

Answer 1

Po prostu panel musi być możliwy do ustawienia. Dodać w dowolnym miejscu utworzyć panel:

panel.setFocusable(true); 
panel.requestFocusInWindow(); 

Oto SSCCE (Proponuję pytaniami z jednym z nich w przyszłości):

import java.awt.Dimension; 
import java.awt.event.KeyEvent; 
import java.awt.event.KeyListener; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.SwingUtilities; 

public class SimpleKeyTest { 

    public static void main(String[] args) { 

     Runnable r = new Runnable() { 

      @Override 
      public void run() { 
       JFrame frame = new JFrame(); 
       JPanel panel = new JPanel(); 

       frame.getContentPane().add(panel); 

       panel.addKeyListener(new KeyListener() { 

        @Override 
        public void keyTyped(KeyEvent e) {} 

        @Override 
        public void keyReleased(KeyEvent e) {} 

        @Override 
        public void keyPressed(KeyEvent e) { 
         System.out.println("Pressed " + e.getKeyChar()); 
        } 
       }); 

       panel.setFocusable(true); 
       panel.requestFocusInWindow(); 

       frame.setSize(new Dimension(300, 300)); 
       frame.setVisible(true); 
      } 

     }; 

     SwingUtilities.invokeLater(r); 

    } 
} 

również https://www.google.com/search?q=jpanel+keylistener

Answer 2

Możesz dodać kluczowy słuchacz JFrame, to jest coś, co robiłem w przeszłości. To prawdopodobnie nie jest dobry pomysł, jeśli masz inne elementy w ramce JFrame.