如何检测特定 window 何时在 java 中关闭

Question

我是 Java 的新手，我试过查找它，但找不到任何有用的东西。我想知道如何检测特定 window 何时关闭？我一直在使用 windowClosing() 但这适用于任何已关闭的 window，因此我希望因 window 关闭而发生的事件也会发生如果 window B 关闭。如何仅在 window A 关闭时检测？抱歉，如果措辞不好，我不知道那么多 Java 术语。提前致谢:)

package gui_login;

//awt classes
import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

//swing classes
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JOptionPane;
import javax.swing.JButton;

public class windowtest implements ActionListener, WindowListener
{
//get JFrame
    JFrame JFrame = new JFrame();

    public static JFrame frameA = new JFrame("FrameA");
    public static JFrame frameB = new JFrame("FrameB");
    static windowtest windowtest = new windowtest();

public static void main(String[] args) 
{
    windowtest.frames();
}

public void frames()
{
    frameA.setLayout(new FlowLayout());
    frameA.setSize(220, 130);
    frameA.setVisible(true);
    frameA.addWindowListener(this);

    frameB.setLayout(new FlowLayout());
    frameB.setSize(220, 130);
    frameB.setVisible(true);
    frameB.addWindowListener(this);
}

public void windowClosing(WindowEvent e) {
    System.out.println("Yo");
}
public void windowActivated(WindowEvent e) {
}
public void windowClosed(WindowEvent e) {
}
public void windowDeactivated(WindowEvent e) {
}
public void windowDeiconified(WindowEvent e) {
}
public void windowIconified(WindowEvent e) {
}
public void windowOpened(WindowEvent e) {
}
public void actionPerformed(ActionEvent e) {
}
}

Answer 1

因为 frameA 和 frameB 使用相同的 WindowListener 实例（this），当任一框架关闭时，您的 WindowListener 会收到通知（both/either).

您可以使用 WindowEvent#getSource 来获取事件的来源，但更简单的解决方案可能是为每个帧提供它们自己的 WindowListener 实例，这样，您就不需要对正在发生的事情做出假设

import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class WindowTest {
//get JFrame

    JFrame JFrame = new JFrame();

    public static JFrame frameA = new JFrame("FrameA");
    public static JFrame frameB = new JFrame("FrameB");
    static WindowTest windowtest = new WindowTest();

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                windowtest.frames();
            }
        });
    }

    public void frames() {
        frameA.setLayout(new FlowLayout());
        frameA.setSize(220, 130);
        frameA.setVisible(true);
        frameA.addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                System.out.println("A is closing");
            }

            @Override
            public void windowClosed(WindowEvent e) {
                System.out.println("A has closed");
            }

        });

        frameB.setLayout(new FlowLayout());
        frameB.setSize(220, 130);
        frameB.setVisible(true);
        frameB.addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                System.out.println("B is closing");
            }

            @Override
            public void windowClosed(WindowEvent e) {
                System.out.println("B has closed");
            }

        });
    }
}

你可能没看过匿名classes，看看Anonymous Classes

一般来说，不再需要您实现不向您的 class 提供直接功能的接口（就像您使用 ActionListener 和 WindowListener 一样），推理也就是说，这些接口需要你实现的方法是public，但实际上没有人应该直接调用它们。

这允许您 "hide" 在您的 class 内部实现细节，并防止未知调用者可能的误用

您可能还想看看 Nested Classes

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