如何防止任务栏中的JFrame警报效果

Question

我是一名 Java SE 开发者，我们的程序只在 windows OS 运行，程序需要打开文件并显示在 UI ，我们在 JInternalFrame 中显示文件内容，并在文件打开时始终 setselected(true)。

最近我们将我们的程序从 JRE1.6.0_41 更新到 JRE1.8.0_144 以解决一个主要错误，并注意到在 JRE1.8 中。0_144 当我们的程序 (JFrame) 未获得焦点并且在 JFrame 的 JInternalFrame 上调用 setselected(true)，JFrame 会在任务栏中闪烁，而 JRE1.6.0_41 不会。有些客户认为这很烦人，因为他们必须经常打开文件。

所以问题是：

(1) 我可以关闭该功能吗？

(2) 如果我不能，有没有其他方法可以避免闪烁效果，同时我仍然可以在 JInternalFrame 上 setSelected()？

如果我没解释好，下面是示例代码演示提醒效果，请运行程序~~最小化到任务栏~~切换到另一个 window，然后它应该会闪烁。我在Windows 7, Windows 8.1 和 Windows 10 上测试过，它们都具有相同的警报效果。

import javax.swing.JInternalFrame;
import javax.swing.SwingUtilities;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;

import java.awt.*;

/*
 * Copy and modified by Oracle sample code "InternalFrameDemo.java"
 */
public class Login extends JFrame {
    JDesktopPane desktop;
    private int m_iFrameCounter = 0;

    public Login() {
        super("InternalFrameDemo");

        //Make the big window be indented 50 pixels from each edge
        //of the screen.
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

        //Set up the GUI.
        desktop = new JDesktopPane(); //a specialized layered pane
        createFrame(); //create first "window"
        setContentPane(desktop);

        //Make dragging a little faster but perhaps uglier.
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);

        // Add new frame every second
        Thread addFrameThread = new Thread() {

            @Override
            public void run() {
                while(true) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            createFrame();
                        }
                    });
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        addFrameThread.start();
    }

    //Create a new internal frame.
    protected void createFrame() {
        JInternalFrame frame = new JInternalFrame();
        frame.setTitle("" + m_iFrameCounter);
        frame.setSize(100, 100);
        frame.setLocation(0, 0);
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        frame.moveToFront();
        try {
            frame.setSelected(true);
        } catch (java.beans.PropertyVetoException e) {}
        m_iFrameCounter++;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        Login frame = new Login();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

更新 01

这是根据@camickr 建议添加 KeyboardFocusManager 和 WindowListener 的更新代码，当 JFrame 获得焦点或 JFrame 获得焦点时，仅在 JInternalFrame 上添加 setselected(true)，但警报仍然存在如果您频繁切换 windows 会发生这种情况，我认为这是因为 JFrame 在 JInternalFrame 上的 setselected(true) 之前失去了焦点。也许有改进代码的方法？

import javax.swing.JInternalFrame;
import javax.swing.SwingUtilities;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;

import java.awt.*;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.beans.PropertyVetoException;

/*
 * Copy and modified by Oracle sample code "InternalFrameDemo.java"
 */
public class Login extends JFrame {
    JDesktopPane desktop;
    private int m_iFrameCounter = 0;
    private JInternalFrame m_InternalFrameWaitSelected = null;

    public Login() {
        super("InternalFrameDemo");

        //Make the big window be indented 50 pixels from each edge
        //of the screen.
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

        //Set up the GUI.
        desktop = new JDesktopPane(); //a specialized layered pane
        createFrame(); //create first "window"
        setContentPane(desktop);

        //Make dragging a little faster but perhaps uglier.
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);

        /*********************************************  update codes *********************************************/ 
        //Add window listener to set last JInternalframe selected when JFrame activated
        this.addWindowListener(new WindowListener() {

            @Override
            public void windowOpened(WindowEvent e) {
            }

            @Override
            public void windowClosing(WindowEvent e) {
            }

            @Override
            public void windowClosed(WindowEvent e) {
            }

            @Override
            public void windowIconified(WindowEvent e) {
            }

            @Override
            public void windowDeiconified(WindowEvent e) {
            }

            @Override
            public void windowActivated(WindowEvent e) {
                if (m_InternalFrameWaitSelected != null) {
                    try {
                        m_InternalFrameWaitSelected.setSelected(true);
                    } catch (PropertyVetoException e1) {
                        e1.printStackTrace();
                    }
                    m_InternalFrameWaitSelected = null;
                }
            }

            @Override
            public void windowDeactivated(WindowEvent e) {
            }

        });
        /*********************************************  update codes *********************************************/

        // Add new frame every 50 millisecond
        Thread addFrameThread = new Thread() {

            @Override
            public void run() {
                while(true) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            createFrame();
                        }
                    });
                    try {
                        Thread.sleep(50);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        addFrameThread.start();
    }

    //Create a new internal frame.
    protected void createFrame() {
        JInternalFrame frame = new JInternalFrame();
        frame.setTitle("" + m_iFrameCounter);
        frame.setSize(100, 100);
        frame.setLocation(0, 0);
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        frame.moveToFront();
        /*********************************************  update codes *********************************************/
        // Only setselect(true) when JFrame is focus owner
        if (KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner() != null &&
                SwingUtilities.isDescendingFrom(KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner(), this)) {
            try {
                frame.setSelected(true);
            } catch (java.beans.PropertyVetoException e) {}
        } else {
            m_InternalFrameWaitSelected = frame;
        }
        /*********************************************  update codes *********************************************/
        m_iFrameCounter++;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        Login frame = new Login();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

更新 02

尝试使用 getGlobalActiveWindow() 和 windowActivated/windowDeactivated，如果频繁切换 windows，警报仍然会发生。下面是测试代码：

getGlobalActiveWindow()

import javax.swing.JInternalFrame;
import javax.swing.SwingUtilities;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;

import java.awt.*;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.beans.PropertyVetoException;

/*
 * Copy and modified by Oracle sample code "InternalFrameDemo.java"
 */
public class Login extends JFrame {
    JDesktopPane desktop;
    private int m_iFrameCounter = 0;
    private JInternalFrame m_InternalFrameWaitSelected = null;
    /*********************************************  update codes *********************************************/ 
    private MyDefaultKeyboardFocusManager m_MyKeyboardFocusManager = new MyDefaultKeyboardFocusManager();

    public class MyDefaultKeyboardFocusManager extends DefaultKeyboardFocusManager {

        //The method is protected, need to add public method to call it
        public Window myGetGlobalActiveWindow() {
            return this.getGlobalActiveWindow();
        }

    }
    /*********************************************  update codes *********************************************/ 

    public Login() {
        super("InternalFrameDemo");

        //Make the big window be indented 50 pixels from each edge
        //of the screen.
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

        //Set up the GUI.
        desktop = new JDesktopPane(); //a specialized layered pane
        setContentPane(desktop);

        //Make dragging a little faster but perhaps uglier.
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);

        /*********************************************  update codes *********************************************/ 
        KeyboardFocusManager.setCurrentKeyboardFocusManager(m_MyKeyboardFocusManager);
        /*********************************************  update codes *********************************************/

        //Add window listener to set last JInternalframe selected when JFrame activated
        this.addWindowListener(new WindowListener() {

            @Override
            public void windowOpened(WindowEvent e) {
            }

            @Override
            public void windowClosing(WindowEvent e) {
            }

            @Override
            public void windowClosed(WindowEvent e) {
            }

            @Override
            public void windowIconified(WindowEvent e) {
            }

            @Override
            public void windowDeiconified(WindowEvent e) {
            }

            @Override
            public void windowActivated(WindowEvent e) {
                if (m_InternalFrameWaitSelected != null) {
                    try {
                        m_InternalFrameWaitSelected.setSelected(true);
                    } catch (PropertyVetoException e1) {
                        e1.printStackTrace();
                    }
                    m_InternalFrameWaitSelected = null;
                }
            }

            @Override
            public void windowDeactivated(WindowEvent e) {
            }

        });

        // Add new frame every 50 millisecond
        Thread addFrameThread = new Thread() {

            @Override
            public void run() {
                while(true) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            createFrame();
                        }
                    });
                    try {
                        Thread.sleep(50);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        addFrameThread.start();
    }

    //Create a new internal frame.
    protected void createFrame() {
        JInternalFrame frame = new JInternalFrame();
        frame.setTitle("" + m_iFrameCounter);
        frame.setSize(100, 100);
        frame.setLocation(0, 0);
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        frame.moveToFront();
        /*********************************************  update codes *********************************************/
        // Only setselect(true) when JFrame is active
        if (m_MyKeyboardFocusManager.myGetGlobalActiveWindow() == this) {
            try {
                frame.setSelected(true);
            } catch (java.beans.PropertyVetoException e) {}
        } else {
            m_InternalFrameWaitSelected = frame;
        }
        /*********************************************  update codes *********************************************/
        m_iFrameCounter++;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        Login frame = new Login();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

windowActivated/windowDeactivated

import javax.swing.JInternalFrame;
import javax.swing.SwingUtilities;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;

import java.awt.*;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.beans.PropertyVetoException;

/*
 * Copy and modified by Oracle sample code "InternalFrameDemo.java"
 */
public class Login extends JFrame {
    JDesktopPane desktop;
    private int m_iFrameCounter = 0;
    private JInternalFrame m_InternalFrameWaitSelected = null;
    /*********************************************  update codes *********************************************/ 
    private boolean m_bIsFrameActive = false;
    /*********************************************  update codes *********************************************/ 

    public Login() {
        super("InternalFrameDemo");

        //Make the big window be indented 50 pixels from each edge
        //of the screen.
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

        //Set up the GUI.
        desktop = new JDesktopPane(); //a specialized layered pane
        setContentPane(desktop);

        //Make dragging a little faster but perhaps uglier.
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);

        /*********************************************  update codes *********************************************/ 
        //Add window listener to set last JInternalframe selected when JFrame activated
        this.addWindowListener(new WindowListener() {

            @Override
            public void windowOpened(WindowEvent e) {
            }

            @Override
            public void windowClosing(WindowEvent e) {
            }

            @Override
            public void windowClosed(WindowEvent e) {
            }

            @Override
            public void windowIconified(WindowEvent e) {
            }

            @Override
            public void windowDeiconified(WindowEvent e) {
            }

            @Override
            public void windowActivated(WindowEvent e) {
                m_bIsFrameActive = true;
                if (m_InternalFrameWaitSelected != null) {
                    try {
                        m_InternalFrameWaitSelected.setSelected(true);
                    } catch (PropertyVetoException e1) {
                        e1.printStackTrace();
                    }
                    m_InternalFrameWaitSelected = null;
                }
            }

            @Override
            public void windowDeactivated(WindowEvent e) {
                m_bIsFrameActive = false;
            }

        });
        /*********************************************  update codes *********************************************/

        // Add new frame every 50 millisecond
        Thread addFrameThread = new Thread() {

            @Override
            public void run() {
                while(true) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            createFrame();
                        }
                    });
                    try {
                        Thread.sleep(50);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        addFrameThread.start();
    }

    //Create a new internal frame.
    protected void createFrame() {
        JInternalFrame frame = new JInternalFrame();
        frame.setTitle("" + m_iFrameCounter);
        frame.setSize(100, 100);
        frame.setLocation(0, 0);
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        frame.moveToFront();
        /*********************************************  update codes *********************************************/
        // Only setselect(true) when JFrame is active
        if (m_bIsFrameActive) {
            try {
                frame.setSelected(true);
            } catch (java.beans.PropertyVetoException e) {}
        } else {
            m_InternalFrameWaitSelected = frame;
        }
        /*********************************************  update codes *********************************************/
        m_iFrameCounter++;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        Login frame = new Login();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Answer 1

we display the file contents in JInternalFrame and always setselected(true) when the file is opened.

不知道如何停止任务栏上的闪烁，但您可以通过不自动调用 setSelected() 来更改行为。

例如，您可以：

仅在框架处于活动状态时调用 setSelected() window。您可以使用 KeyboardFocusManager 检查 window 是否聚焦。
向框架添加一个WindowListener并处理windowActivated事件以在最近打开的内部框架上调用setSelected()方法。

编辑：

run the program and minimize it into taskbar,

首先我要澄清的是，如果我将框架最小化到任务栏，图标闪烁是没有问题的。

仅当我单击另一个应用程序时图标才会闪烁，并且登录框架在打开时失去焦点。

the alert still happen if you switch windows frequently,

我将您的代码更改为：

//if (KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner() != null &&
//    SwingUtilities.isDescendingFrom(KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner(), this)) {
if (KeyboardFocusManager.getCurrentKeyboardFocusManager().getActiveWindow() == this)
{
    try
    {
        System.out.println("active");
        frame.setSelected(true);
    }
    catch (java.beans.PropertyVetoException e) {}
}
else
{
    System.out.println("not");
//  frame = m_InternalFrameWaitSelected;
    m_InternalFrameWaitSelected = frame;
}

我注意到有时 "active" 会显示在另一个 window 中，即使它正在玩游戏。所以出于某种原因，KeyboardFocusManager 返回了一个不正确的值（或者我不明白该方法应该如何工作？）

所以也许你可以尝试使用 getGlobalActiveWindow() 方法看看它是否有任何不同。

如果没有，那么我的下一个建议是忘记 KeyboardFocusManager 并管理一个布尔变量，该变量指示您的框架是否处于活动状态。因此，您可以在 windowActivated 中设置变量 true，在 windowDeactivated 中设置 false。然后在创建框架时测试此变量。

另请注意我是如何更改以下代码的：

//  frame = m_InternalFrameWaitSelected;
    m_InternalFrameWaitSelected = frame;

Answer 2

如果有人有兴趣解答，我追查JInternalFrame中的源代码后，发现闪烁效果是由调用setSelected(true)时的requestFocus()引起的，所以我决定继承JInternalFrame，将requestFocus()替换为requestFocusInWindow()，现在闪烁效果消失了。

这是我对这个问题的最终解决方案：

import javax.swing.JInternalFrame;
import javax.swing.SwingUtilities;

import sun.swing.SwingUtilities2;

import javax.swing.InternalFrameFocusTraversalPolicy;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;

import java.awt.*;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.beans.PropertyVetoException;

/*
 * Copy and modified by Oracle sample code "InternalFrameDemo.java"
 */
public class Login extends JFrame {
    JDesktopPane desktop;
    private int m_iFrameCounter = 0;

    /**
     * This class is created to handle problem that program would blink in taskbar 
     * when call setSelected(true) on JInternalFrame base on JRE1.8.0_144, the only different content is
     * use lastFocusOwner.requestFocusInWindow(); instead of lastFocusOwner.requestFocus(); 
     * in method restoreSubcomponentFocus() 
     *
     */
    public class MyInternalFrame extends JInternalFrame {

        private Component lastFocusOwner;
        private final String BASE_JRE_VERSION = "1.8.0_144";

        public MyInternalFrame() {
            _checkJavaVersion();
        }

        public MyInternalFrame(String title) {
            super(title);
            _checkJavaVersion();
        }

        public MyInternalFrame(String title, boolean resizable) {
            super(title, resizable);
            _checkJavaVersion();
        }

        public MyInternalFrame(String title, boolean resizable, boolean closable) {
            super(title, resizable, closable);
            _checkJavaVersion();
        }

        public MyInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable) {
            super(title, resizable, closable, maximizable);
            _checkJavaVersion();
        }

        public MyInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable, boolean iconifiable) {
            super(title, resizable, closable, maximizable, iconifiable);
            _checkJavaVersion();
        }

        private void _checkJavaVersion() {
            if (!BASE_JRE_VERSION.equals(System.getProperty("java.version")))
                System.err.println(String.format("%s is not compatible with current Java runtime version : %s ", this.getClass().toString(), System.getProperty("java.version")));
        }

        @Override
        public void restoreSubcomponentFocus() {
            if (isIcon()) {
                SwingUtilities2.compositeRequestFocus(getDesktopIcon());
            }
            else {
                Component component = KeyboardFocusManager.getCurrentKeyboardFocusManager().getPermanentFocusOwner();
                if ((component == null) || !SwingUtilities.isDescendingFrom(component, this)) {
                    // FocusPropertyChangeListener will eventually update
                    // lastFocusOwner. As focus requests are asynchronous
                    // lastFocusOwner may be accessed before it has been correctly
                    // updated. To avoid any problems, lastFocusOwner is immediately
                    // set, assuming the request will succeed.
                    setLastFocusOwner(getMostRecentFocusOwner());
                    if (lastFocusOwner == null) {
                        // Make sure focus is restored somewhere, so that
                        // we don't leave a focused component in another frame while
                        // this frame is selected.
                        setLastFocusOwner(getContentPane());
                    }
                    lastFocusOwner.requestFocusInWindow();
                }
            }
        }

        private void setLastFocusOwner(Component component) {
            lastFocusOwner = component;
        }

        @Override
        public Component getMostRecentFocusOwner() {
            if (isSelected()) {
                return getFocusOwner();
            }

            if (lastFocusOwner != null) {
                return lastFocusOwner;
            }

            FocusTraversalPolicy policy = getFocusTraversalPolicy();
            if (policy instanceof InternalFrameFocusTraversalPolicy) {
                return ((InternalFrameFocusTraversalPolicy)policy).
                    getInitialComponent(this);
            }

            Component toFocus = policy.getDefaultComponent(this);
            if (toFocus != null) {
                return toFocus;
            }
            return getContentPane();
        }

        @Override
        public Component getFocusOwner() {
            if (isSelected()) {
                return lastFocusOwner;
            }
            return null;
        }
    }

    public Login() {
        super("InternalFrameDemo");

        //Make the big window be indented 50 pixels from each edge
        //of the screen.
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

        //Set up the GUI.
        desktop = new JDesktopPane(); //a specialized layered pane
        setContentPane(desktop);

        //Make dragging a little faster but perhaps uglier.
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);

        // Add new frame every 50 millisecond
        Thread addFrameThread = new Thread() {

            @Override
            public void run() {
                while(true) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            createFrame();
                        }
                    });
                    try {
                        Thread.sleep(50);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        addFrameThread.start();
    }

    //Create a new internal frame.
    protected void createFrame() {
        JInternalFrame frame = new MyInternalFrame();
        frame.setTitle("" + m_iFrameCounter);
        frame.setSize(100, 100);
        frame.setLocation(0, 0);
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        frame.moveToFront();
        try {
            frame.setSelected(true);
        } catch (java.beans.PropertyVetoException e) {}
        m_iFrameCounter++;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        Login frame = new Login();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

如何防止任务栏中的JFrame警报效果

How to prevent JFrame alert effect in taskbar

java

swing

taskbar

jframe

jinternalframe