在运行时删除顶级容器

java runtime swing jdialog

2022-09-02 11:41:40

不幸的是，看起来这个最近关闭的问题没有得到很好的理解。以下是典型输出：

run:
    Trying to Remove JDialog
    Remove Cycle Done :-)
    Checking if still exists any of TopLayoutContainers
JFrame
JDialog
    Will Try Remove Dialog again, CycleNo. 1
 -----------------------------------------------------------
    Trying to Remove JDialog
    Remove Cycle Done :-)
    Checking if still exists any of TopLayoutContainers
JFrame
JDialog
    Will Try Remove Dialog again, CycleNo. 2
 -----------------------------------------------------------
    Trying to Remove JDialog
    Remove Cycle Done :-)
    Checking if still exists any of TopLayoutContainers
JFrame
JDialog
    Will Try Remove Dialog again, CycleNo. 3
 -----------------------------------------------------------
    Trying to Remove JDialog
    Remove Cycle Done :-)
    Checking if still exists any of TopLayoutContainers
JFrame
JDialog
*** End of Cycle Without Success, Exit App ***
BUILD SUCCESSFUL (total time: 13 seconds)

我会再次尝试问这个问题：我如何在运行时上 kil*l 第一个打开的顶级，并帮助我关闭一个 Swing NightMares？Container

import java.awt.*;
import java.awt.event.WindowEvent;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;

public class RemoveDialogOnRuntime extends JFrame {

    private static final long serialVersionUID = 1L;
    private int contID = 1;
    private boolean runProcess;
    private int top = 20;
    private int left = 20;
    private int maxLoop = 0;

    public RemoveDialogOnRuntime() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(300, 300));
        setTitle("Remove Dialog On Runtime");
        setLocation(150, 150);
        pack();
        setVisible(true);
        Point loc = this.getLocation();
        top += loc.x;
        left += loc.y;
        AddNewDialog();
    }

    private void AddNewDialog() {
        DialogRemove firstDialog = new DialogRemove();
        remWins();
    }

    private void remWins() {
        runProcess = true;
        Thread th = new Thread(new RemTask());
        th.setDaemon(false);
        th.setPriority(Thread.MIN_PRIORITY);
        th.start();
    }

    private class RemTask implements Runnable {

        @Override
        public void run() {
            while (runProcess) {
                Window[] wins = Window.getWindows();
                for (int i = 0; i < wins.length; i++) {
                    if (wins[i] instanceof JDialog) {
                        System.out.println("    Trying to Remove JDialog");
                        wins[i].setVisible(false);
                        wins[i].dispose();
                        WindowEvent windowClosing = new WindowEvent(wins[i], WindowEvent.WINDOW_CLOSING);
                        wins[i].dispatchEvent(windowClosing);
                        Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(windowClosing);
                        Runtime runtime = Runtime.getRuntime();
                        runtime.gc();
                        runtime.runFinalization();
                    }
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException ex) {
                        Logger.getLogger(RemoveDialogOnRuntime.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
                wins = null;
                SwingUtilities.invokeLater(new Runnable() {

                    @Override
                    public void run() {
                        System.out.println("    Remove Cycle Done :-)");
                        Runtime.getRuntime().runFinalization();
                        Runtime.getRuntime().gc();
                        runProcess = false;
                    }
                });
            }
            pastRemWins();
        }
    }

    private void pastRemWins() {
        System.out.println("    Checking if still exists any of TopLayoutContainers");
        Window[] wins = Window.getWindows();
        for (int i = 0; i < wins.length; i++) {
            if (wins[i] instanceof JFrame) {
                System.out.println("JFrame");
                wins[i].setVisible(true);
            } else if (wins[i] instanceof JDialog) {
                System.out.println("JDialog");
                wins[i].setVisible(true);
            }
        }
        if (wins.length > 1) {
            wins = null;
            maxLoop++;
            if (maxLoop <= 3) {
                System.out.println("    Will Try Remove Dialog again, CycleNo. " + maxLoop);
                System.out.println(" -----------------------------------------------------------");
                remWins();
            } else {
                System.out.println(" -----------------------------------------------------------");
                System.out.println("*** End of Cycle Without Success, Exit App ***");
                closeMe();
            }
        }
    }

    private void closeMe() {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                System.exit(0);
            }
        });
    }

    private class DialogRemove extends JDialog {

        private static final long serialVersionUID = 1L;

        DialogRemove(final Frame parent) {
            super(parent, "SecondDialog " + (contID++));
            setLocation(top, left);
            top += 20;
            left += 20;
            setPreferredSize(new Dimension(200, 200));
            setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            setModalityType(Dialog.ModalityType.MODELESS);
            pack();
            setVisible(true);
        }

        private DialogRemove() {
            setTitle("SecondDialog " + (contID++));
            setLocation(top, left);
            top += 20;
            left += 20;
            setPreferredSize(new Dimension(200, 200));
            setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            setModalityType(Dialog.ModalityType.MODELESS);
            pack();
            setVisible(true);
        }
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                RemoveDialogOnRuntime superConstructor = new RemoveDialogOnRuntime();
            }
        });
    }
}

答案 1

调用 dispose（） 允许主机平台回收重量级对等体消耗的内存，但在 .即便如此，也是一个建议。WINDOW_CLOSINGEventQueuegc()

附录：查看噩梦的另一种方法是通过分析器。运行下面的例子，可以看到定期收集永远不会完全返回到基线。我通过人为地从一个小堆开始来夸大垂直轴。此处显示了其他示例。当内存非常有限时，我使用了两种方法：jvisualvm

紧急：从命令行循环，每次启动一个新的 VM。
紧急：完全消除重量级组件，无头运行，仅使用2D图形和轻量级组件进行组合。BufferedImage

enter image description here

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.WindowEvent;
import javax.swing.JDialog;

/** @see https://stackoverflow.com/questions/6309407 */
public class DialogClose extends JDialog {

    public DialogClose(int i) {
        this.setTitle("Dialog " + String.valueOf(i));
        this.setPreferredSize(new Dimension(320, 200));
    }

    private void display() {
        this.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
        this.pack();
        this.setLocationRelativeTo(null);
        this.setVisible(true);
        passSomeTime();
        this.setVisible(false);
        this.dispatchEvent(new WindowEvent(
            this, WindowEvent.WINDOW_CLOSING));
        this.dispose();
        passSomeTime();
    }

    private void passSomeTime() {
        try {
            Thread.sleep(100);
        } catch (InterruptedException ie) {
            ie.printStackTrace(System.err);
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                int count = 0;
                while (true) {
                    new DialogClose(count++).display();
                }
            }
        });
    }
}

答案 2

我已经完全重新设计了你的例子：

我已经简化了不需要的东西（，未使用的构造函数...）setLocation()
我已经删除了触发WINDOW_CLOSING事件的代码（无用）
我已经删除了将所有窗口重置为再次可见的代码（这将阻止GC在其上）
我使用了 a 而不是 a 来处理对话框javax.swing.TimerThread
我已经使用了一个强制GC（在EDT中不是一个好主意）Thread
我已经修改了最终的成功标准以检查2（而不是1），因为在Swing中，如果您打开一个没有父级的对话框，那么将创建一个特殊的不可见框架以将其用作父级（实际上对于所有无所有者的对话），一旦创建，该框架就无法删除。Window.getWindows()

生成的代码段如下：

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

public class RemoveDialogOnRuntime extends JFrame {

    private static final long serialVersionUID = 1L;
    private boolean runProcess;
    private int maxLoop = 0;
    private Timer timer;

    public RemoveDialogOnRuntime() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(300, 300));
        setTitle("Remove Dialog On Runtime");
        setLocation(150, 150);
        pack();
        setVisible(true);
        addNewDialog();
    }

    private void addNewDialog() {
        DialogRemove firstDialog = new DialogRemove();
        remWins();
    }

    private void remWins() {
        runProcess = true;
        timer = new Timer(1000, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (runProcess) {
                    for (Window win: Window.getWindows()) {
                        if (win instanceof JDialog) {
                            System.out.println("    Trying to Remove JDialog");
                            win.dispose();
                        }
                    }
                    System.out.println("    Remove Cycle Done :-)");
                    runProcess = false;
                    new Thread() {
                        @Override
                        public void run() {
                            try {
                                Thread.sleep(100);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                            Runtime.getRuntime().gc();
                        }
                    }.start();
                } else {
                    pastRemWins();
                    runProcess = true;
                }
            }
        });
        timer.setRepeats(true);
        timer.start();
    }

    private void pastRemWins() {
        System.out.println("    Checking if still exists any of TopLayoutContainers");
        Window[] wins = Window.getWindows();
        for (int i = 0; i < wins.length; i++) {
            if (wins[i] instanceof JFrame) {
                System.out.println("JFrame");
            } else if (wins[i] instanceof JDialog) {
                System.out.println("JDialog");
            } else {
                System.out.println(wins[i].getClass().getSimpleName());
            }
        }
        // We must expect 2 windows here: this (RemoveDialogOnRuntime) and the parent of all parentless dialogs
        if (wins.length > 2) {
            wins = null;
            maxLoop++;
            if (maxLoop <= 3) {
                System.out.println("    Will Try Remove Dialog again, CycleNo. " + maxLoop);
                System.out.println(" -----------------------------------------------------------");
                remWins();
            } else {
                System.out.println(" -----------------------------------------------------------");
                System.out.println("*** End of Cycle Without Success, Exit App ***");
                closeMe();
            }
        } else {
            timer.stop();
        }
    }

    private void closeMe() {
        System.exit(0);
    }

    private class DialogRemove extends JDialog {

        private static final long serialVersionUID = 1L;

        private DialogRemove() {
            setTitle("SecondDialog");
            setPreferredSize(new Dimension(200, 200));
            setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            setModalityType(Dialog.ModalityType.MODELESS);
            pack();
            setVisible(true);
        }
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                RemoveDialogOnRuntime superConstructor = new RemoveDialogOnRuntime();
            }
        });
    }
}

重要的结论是：

您无法删除由 Swing 创建的不可见框架，该框架是所有无主对话框的父级
您必须强制从中删除已处置对话框的GC（对我来说，该对话框看起来像一个错误，但我认为原因是Swing对所有窗口都保留了一个，并且在GC发生之前不会释放它。Window.getWindows()WeakReferenceWeakReference

希望这能为您的问题提供清晰完整的答案。