按下键盘上的箭头如何对应程序里的箭头

按下键盘上的箭头怎么对应程序里的箭头?
书上有个小项目 说是在一定时间输入一定数量的字符串 ...我想把输入的字符串改成箭头↑ ↓ ← →
但是我在键盘上按下这些键时 怎么判断我输入的是什么 . 该怎么实现 ?
  这个 只是我看书上的例子后有这个想法. 不知道怎么做了 ..

[解决办法]
这里给你贴一个具体的实例，但是还有点小问题就是 左箭头的具体实现要再用程序控制光标

Java code

import javax.swing.*;import java.awt.event.KeyListener;import java.awt.event.KeyEvent;public class KeyListenerFrame extends JFrame implements KeyListener {    private JTextArea jta=new JTextArea(10,10);    public KeyListenerFrame(String title){        super(title);        jta.addKeyListener(this);        this.getContentPane().add(jta);        this.pack();        this.setVisible(true);        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        this.setLocationRelativeTo(null);    }    public static void main(String[] args) {        new  KeyListenerFrame("demo");    }    @Override    public void keyTyped(KeyEvent e) {        //To change body of implemented methods use File | Settings | File Templates.//        if(e.getKeyCode()==KeyEvent.VK_DOWN){//              jta.append("↓");//        }    }    @Override    public void keyPressed(KeyEvent e) {         switch(e.getKeyCode()){            case KeyEvent.VK_DOWN:                jta.append("↓");                break;            case KeyEvent.VK_UP:                jta.append("↑");                break;            case KeyEvent.VK_LEFT:                jta.append("←");                break;            case KeyEvent.VK_RIGHT:                jta.append("→");                break;//            default://                jta.append(""+e.getKeyChar());        }    }    @Override    public void keyReleased(KeyEvent e) {        //To change body of implemented methods use File | Settings | File Templates.    }}
[解决办法]
这里给你贴一个具体的实例，但是还有点小问题就是 左箭头的具体实现要再用程序控制光标
Java code
import javax.swing.*;import java.awt.event.KeyListener;import java.awt.event.KeyEvent;public class KeyListenerFrame extends JFrame implements KeyListener {    private JTextArea jta=new JTextArea(10,10);    public KeyListenerFrame(String title){        super(title);        jta.addKeyListener(this);        this.getContentPane().add(jta);        this.pack();        this.setVisible(true);        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        this.setLocationRelativeTo(null);    }    public static void main(String[] args) {        new  KeyListenerFrame("demo");    }    @Override    public void keyTyped(KeyEvent e) {        //To change body of implemented methods use File | Settings | File Templates.//        if(e.getKeyCode()==KeyEvent.VK_DOWN){//              jta.append("↓");//        }    }    @Override    public void keyPressed(KeyEvent e) {         switch(e.getKeyCode()){            case KeyEvent.VK_DOWN:                jta.append("↓");                break;            case KeyEvent.VK_UP:                jta.append("↑");                break;            case KeyEvent.VK_LEFT:                jta.append("←");                break;            case KeyEvent.VK_RIGHT:                jta.append("→");                break;//            default://                jta.append(""+e.getKeyChar());        }    }    @Override    public void keyReleased(KeyEvent e) {        //To change body of implemented methods use File | Settings | File Templates.    }}