AWT KeyListener 接口

处理 KeyEvent 的类应实现此接口。该类的对象必须与某组件登记。可以使用 addKeyListener() 方法登记该对象。

接口声明

以下为 java.awt.event.KeyListener 接口的声明

public interface KeyListener
   extends EventListener

接口方法

继承的方法

此接口从以下接口继承方法

• java.awt.EventListener

KeyListener 示例

通过任意你选择的编辑器创建以下 Java 程序，位于 D:/ > AWT > com > tutorialspoint > gui > 中

package com.tutorialspoint.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) {            
      }    
   } 
}

使用命令提示符编译此程序。转至 D:/ > AWT 并键入以下命令。

D:\AWT>javac com\tutorialspoint\gui\AwtListenerDemo.java

如果没有错误，则表示编译成功。使用以下命令运行此程序。

D:\AWT>java com.tutorialspoint.gui.AwtListenerDemo

确认以下输出