Swing KeyListener接口
類處理該KeyEvent類的對象應該實現這個接口。一個組件必須註冊。使用addKeyListener()方法，該對象可以被註冊。
接口聲明
以下是聲明 java.awt.event.KeyListener接口：
public interface KeyListener extends EventListener
接口方法
S.N.
方法 & 描述
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.
方法繼承
這個接口從以下接口繼承的方法：
- java.awt.EventListener
KeyListener 例子
選擇使用任何編輯器創建以下java程序在 D:/ > SWING > com > yiibai > gui >
SwingListenerDemo.java
package com.yiibai.gui; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class SwingListenerDemo { private JFrame mainFrame; private JLabel headerLabel; private JLabel statusLabel; private JPanel controlPanel; public SwingListenerDemo(){ prepareGUI(); } public static void main(String[] args){ SwingListenerDemo swingListenerDemo = new SwingListenerDemo(); swingListenerDemo.showKeyListenerDemo(); } private void prepareGUI(){ mainFrame = new JFrame("Java SWING Examples"); mainFrame.setSize(400,400); mainFrame.setLayout(new GridLayout(3, 1)); headerLabel = new JLabel("",JLabel.CENTER ); statusLabel = new JLabel("",JLabel.CENTER); statusLabel.setSize(350,100); mainFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent windowEvent){ System.exit(0); } }); controlPanel = new JPanel(); controlPanel.setLayout(new FlowLayout()); mainFrame.add(headerLabel); mainFrame.add(controlPanel); mainFrame.add(statusLabel); mainFrame.setVisible(true); } private JTextField textField; private void showKeyListenerDemo(){ headerLabel.setText("Listener in action: KeyListener"); textField = new JTextField(10); textField.addKeyListener(new CustomKeyListener()); JButton okButton = new JButton("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:/ > SWING 然後輸出以下命令。
D:SWING>javac comyiibaiguiSwingListenerDemo.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:SWING>java com.yiibai.gui.SwingListenerDemo
驗證下面的輸出
