JPopup菜单不显示

Question

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这样做的目的是创建一个JPopupMenu，当我在它上LEFT CLICK时，它就会出现在感叹号下面。

我没有使用isPopupTrigger()方法，因为我已经创建了一个单独的MouseInputHandler来实现我的特定条件。

然而，JPopupMenu没有出现。

以下是代码：

protected class LabelHandler extends MouseInputAdapter{


    @Override
    public void mouseClicked(MouseEvent e){
        JLabel cause = (JLabel) e.getSource();
        if(cause == saveLabel){
            try{
                desktop.open(f);
            }catch(IOException ex){
                ex.printStackTrace();
            }
        }else if(cause == downLabel){

            popup.show(ScreenRecorder.this, e.getX(),e.getY());
        }
    }

    @Override
    public void mouseEntered(MouseEvent e){
        JLabel cause = (JLabel) e.getSource();
        if(cause == saveLabel){
            saveLabel.setCursor(new Cursor(Cursor.HAND_CURSOR));
        }else if(cause == downLabel){
            downLabel.setCursor(new Cursor(Cursor.HAND_CURSOR));
        }
    }

    @Override
    public void mouseExited(MouseEvent e){
        JLabel cause = (JLabel) e.getSource();
        if(cause == saveLabel || cause == saveLabel){
            saveLabel.setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
        }else if(cause == downLabel){
            downLabel.setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
        }
    }
}

这个标签被命名为downLabel，因为它应该是一个指向向下的箭头，但是无论如何，我在那里加了一个感叹号。请告诉我为什么JPopupMenu没有出现。是的，我用另一种方法设置菜单。

编辑：

创建JPopup的代码：

public void setupJPopup(){
        encodingGroup.add(avi);
        encodingGroup.add(quicktime);

        popup.add(avi);
        popup.add(quicktime);
        popup.addSeparator();

        recordingAreaGroup.add(entireScreen);
        recordingAreaGroup.add(custom);

        popup.add(entireScreen);
        popup.add(custom);
        popup.addSeparator();

        cursorGroup.add(selectBlackCursor);
        cursorGroup.add(selectWhiteCursor);
        cursorGroup.add(selectNoCursor);

        selectCursor.add(selectBlackCursor);
        selectCursor.add(selectWhiteCursor);
        selectCursor.add(selectNoCursor);

        popup.add(selectCursor);
        popup.pack();
    }  

上述代码中涉及的变量是：

/* Creating the JPopupMenu containing the various menu items */
    JPopupMenu popup = new JPopupMenu();

    ButtonGroup encodingGroup = new ButtonGroup();
    ButtonGroup recordingAreaGroup = new ButtonGroup();
    ButtonGroup cursorGroup = new ButtonGroup();

    /* Handler for labels*/
    LabelHandler labelHandler = new LabelHandler();

    JRadioButtonMenuItem avi = new JRadioButtonMenuItem("AVI",true);
    JRadioButtonMenuItem quicktime = new JRadioButtonMenuItem("QuickTime",false);
    JRadioButtonMenuItem entireScreen = new JRadioButtonMenuItem("Entire Screen",true);
    JRadioButtonMenuItem custom = new JRadioButtonMenuItem("Custom...",false);
    JMenu selectCursor = new JMenu("Select a cursor");
    JRadioButtonMenuItem selectWhiteCursor = new JRadioButtonMenuItem("White Cursor",true);
    JRadioButtonMenuItem selectBlackCursor = new JRadioButtonMenuItem("Black Cursor",false);
    JRadioButtonMenuItem selectNoCursor = new JRadioButtonMenuItem("No Cursor",false);
/* Icons for the cursors */
    Icon blackCursor = (Icon) new ImageIcon("src/images/blackCursor.png");
    Icon whiteCursor = (Icon) new ImageIcon("src/images/whiteCursor.png");

Answer 1

你能把popup的相关代码寄出去吗？

或者更好的SSCCE。

我不能重现你的问题。

你应该用

saveLabel.equals(cause)

.的

cause == saveLabel

Answer 2

这个例子对我有用。我看到你的问题有一段时间了--然后我意识到我从来没有调用过setupJPopup()方法--也许这也是你的问题？否则，您是否可以开始将代码中的内容添加到此示例中，直到重新创建问题为止？

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

public class PopupMenu extends Box{

    Dimension preferredSize = new Dimension(400,30);

    JPopupMenu popup = new JPopupMenu();

    ButtonGroup encodingGroup = new ButtonGroup();
    ButtonGroup recordingAreaGroup = new ButtonGroup();
    ButtonGroup cursorGroup = new ButtonGroup();

    JRadioButtonMenuItem avi = new JRadioButtonMenuItem("AVI",true);
    JRadioButtonMenuItem quicktime = new JRadioButtonMenuItem("QuickTime",false);
    JRadioButtonMenuItem entireScreen = new JRadioButtonMenuItem("Entire Screen",true);
    JRadioButtonMenuItem custom = new JRadioButtonMenuItem("Custom...",false);
    JMenu selectCursor = new JMenu("Select a cursor");
    JRadioButtonMenuItem selectWhiteCursor = new JRadioButtonMenuItem("White Cursor",true);
    JRadioButtonMenuItem selectBlackCursor = new JRadioButtonMenuItem("Black Cursor",false);
    JRadioButtonMenuItem selectNoCursor = new JRadioButtonMenuItem("No Cursor",false);
    //Icons for the cursors 
    Icon blackCursor = (Icon) new ImageIcon("src/images/blackCursor.png");
    Icon whiteCursor = (Icon) new ImageIcon("src/images/whiteCursor.png");

    public PopupMenu(){
        super(BoxLayout.Y_AXIS);

        // The part I was missing and was throwing me for a loop
        // Maybe you're not calling this method, and therefore not setting up the popup menu???
        setupJPopup();

        //Other normal stuff
        JLabel clickMe = new JLabel("ClickMe");
        clickMe.setAlignmentX(RIGHT_ALIGNMENT);
        clickMe.addMouseListener(new MouseAdapter(){

            @Override
            public void mouseClicked(MouseEvent e) {
                popup.show(e.getComponent(), e.getX(), e.getY());
            }});

        add(clickMe);       
    }

    public void setupJPopup(){
        encodingGroup.add(avi);
        encodingGroup.add(quicktime);

        popup.add(avi);
        popup.add(quicktime);
        popup.addSeparator();

        recordingAreaGroup.add(entireScreen);
        recordingAreaGroup.add(custom);

        popup.add(entireScreen);
        popup.add(custom);
        popup.addSeparator();

        cursorGroup.add(selectBlackCursor);
        cursorGroup.add(selectWhiteCursor);
        cursorGroup.add(selectNoCursor);

        selectCursor.add(selectBlackCursor);
        selectCursor.add(selectWhiteCursor);
        selectCursor.add(selectNoCursor);

        popup.add(selectCursor);
        popup.pack();
    }  


    public Dimension getPreferredSize(){
        return preferredSize;
    }

    public static void main(String[] args) {

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setContentPane(new PopupMenu());
        frame.validate();
        frame.pack();
        frame.setVisible(true);
    }
}