KeyListener 介面

KeyEvent類的對象應該實現這個介面。一個組件必須註冊。使用addKeyListener（）方法，該對象需要註冊。

介面聲明

以下是聲明的java.awt.event.KeyListener介面：

public interface KeyListener
   extends EventListener

介面中的方法

繼承的方法

這個介面繼承的方法從下麵的介面：

• java.awt.EventListener

keyListener 示例

選擇使用任何編輯器創建以下java程式 D:/ > AWT > com > zaixian > gui >

package com.zaixian.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtListenerDemo {
   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;
   private TextField textField;

   public AwtListenerDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtListenerDemo  awtListenerDemo = new AwtListenerDemo();
      awtListenerDemo.showKeyListenerDemo();
   }

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }
      });

      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);
   }

   private void showKeyListenerDemo(){
      headerLabel.setText("Listener in action: KeyListener");

      textField  = new TextField(10);

      textField.addKeyListener(new CustomKeyListener());
      Button okButton = new Button("OK");
      okButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            statusLabel.setText("Entered text: " + textField.getText());
         }
      });

      controlPanel.add(textField);
      controlPanel.add(okButton);
      mainFrame.setVisible(true);
   }

   class CustomKeyListener implements KeyListener{
      public void keyTyped(KeyEvent e) {
      }

      public void keyPressed(KeyEvent e) {
         if(e.getKeyCode() == KeyEvent.VK_ENTER){
            statusLabel.setText("Entered text: " + textField.getText());
         }
      }

      public void keyReleased(KeyEvent e) {
      }
   }
}

編譯程序，使用命令提示符。到 D:/ > AWT 然後鍵入以下命令。

D:AWT>javac comzaixianguiAwtListenerDemo.java

如果沒有錯誤出現，這意味著編譯成功。使用下麵的命令來運行程式。

D:AWT>java com.zaixian.gui.AwtListenerDemo

驗證下麵的輸出