Swing FocusAdapter類

FocusAdapter類是一個抽象(介面卡)類，用於接收鍵盤焦點事件。此類的所有方法都是空的，此類是用於建立偵聽器物件的便捷類。

類宣告

以下是java.awt.event.FocusAdapter類的宣告 -

public abstract class FocusAdapter
   extends Object
      implements FocusListener

類建構函式

類方法

方法繼承

該類繼承以下類中的方法 -

• java.lang.Object

FocusAdapter範例

使用編輯器建立以下Java程式：FocusAdapterExample.java

package com.yiibai.swing.listener;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class FocusAdapterExample {
    private JFrame mainFrame;
    private JLabel headerLabel;
    private JLabel statusLabel;
    private JPanel controlPanel;

    public FocusAdapterExample() {
        prepareGUI();
    }

    public static void main(String[] args) {
        FocusAdapterExample swingAdapterDemo = new FocusAdapterExample();
        swingAdapterDemo.showFocusAdapterDemo();
    }

    private void prepareGUI() {
        mainFrame = new JFrame("Java SWING FocusAdapter範例(tw511.com)");
        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 void showFocusAdapterDemo() {
        headerLabel.setText("Listener in action: FocusAdapter");
        JButton okButton = new JButton("確定");
        JButton cancelButton = new JButton("取消");

        okButton.addFocusListener(new FocusAdapter() {
            public void focusGained(FocusEvent e) {
                statusLabel.setText(
                        statusLabel.getText() + e.getComponent().getClass().getSimpleName() + " gained focus. ");
            }
        });
        cancelButton.addFocusListener(new FocusAdapter() {
            public void focusLost(FocusEvent e) {
                statusLabel
                        .setText(statusLabel.getText() + e.getComponent().getClass().getSimpleName() + " lost focus. ");
            }
        });
        controlPanel.add(okButton);
        controlPanel.add(cancelButton);
        mainFrame.setVisible(true);
    }
}

執行上面範例程式碼，得到以下結果：