KeyListener 接口

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

接口聲明

以下是聲明的java.awt.event.KeyListener接口:

public interface KeyListener extends EventListener

接口中的方法

S.N.

方法&說明

1

void keyPressed(KeyEvent e)
Invoked when a key has been pressed.

2

void keyReleased(KeyEvent e)
Invoked when a key has been released.

3

void keyTyped(KeyEvent e)
Invoked when a key has been typed.

繼承的方法

這個接口繼承的方法從下面的接口:

  • java.awt.EventListener

keyListener 示例

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

AwtListenerDemo

package com.yiibai.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 comyiibaiguiAwtListenerDemo.java

如果沒有錯誤出現,這意味着編譯成功。使用下面的命令來運行程序。

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

驗證下面的輸出

AWT