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

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class KeyEventDemo extends JFrame implements KeyListener {
    /**
     * 
     */
    private static final long serialVersionUID = -9124455865998643315L;
    private static KeyEventDemo frm;
    private static JTextField tf;
    private static JTextArea ta;
    static {
    if (frm == null)
        frm = new KeyEventDemo();
    if (tf == null)
        tf = new JTextField(20);
    if (ta == null)
        ta = new JTextArea("", 5, 20);
    }

    public static void main(String args[]) {
    frm.setSize(500, 300);
    frm.setTitle("KeyEvent Demo");
    frm.setLayout(new FlowLayout(FlowLayout.CENTER));
    tf.addKeyListener(frm);
    ta.setEditable(false);
    frm.add(tf);
    frm.add(ta);
    frm.setVisible(true);
    }

    // 当tf组件触发KeyEvent事件时，根据事件的种类执行下列的程序代码
    public void keyPressed(KeyEvent e) { // 当按键按下时
    switch (e.getKeyCode()) {
    case KeyEvent.VK_A: {
        ta.append("恭喜，你按下了a键\r\n");
        break;
    }
    case KeyEvent.VK_B: {
        ta.append("恭喜，你按下了b键\r\n");
        break;
    }
    default: {
        return;
    }
    }

    }

    public void keyReleased(KeyEvent e) { // 当按键放开时
    // ta.append("keyReleased() 被调用\n");
    }

    public void keyTyped(KeyEvent e) { // 键入内容时
    // ta.append("keyTyped() 被调用\n");
    }
}

------解决方案--------------------
public void keyTyped(KeyEvent e) { // 键入内容时
   // ta.append("keyTyped() 被调用\n");
   }
}


------解决方案--------------------
JAVA技术总群  161734506 欢迎爱好者加入