java – 从JButton显示/隐藏JPopupMenu; FocusListener无法正常

>单击时显示弹出窗口
>如果再次点击,请隐藏它
>如果在弹出窗口中选择了某个项目,则将其隐藏
>如果用户点击屏幕中的其他位置,则隐藏它

这4件事情都有效,但由于我正在使用的布尔标志,如果用户点击其他地方或选择了一个项目,我必须在按钮上单击两次才会再次显示.这就是为什么我试图添加一个FocusListener(绝对没有响应)来修复它并在这些情况下将标志设置为false.

编辑：最后一次尝试回答帖子……

以下是监听器:(它在一个扩展JButton的类中,所以第二个监听器在JButton上.)

// Show popup on left click.
menu.addFocusListener(new FocusListener() {
 @Override
 public void focusLost(FocusEvent e) {
  System.out.println("LOST FOCUS");
  isShowingPopup = false;
 }

 @Override
 public void focusGained(FocusEvent e) {
  System.out.println("GAINED FOCUS");
 }
});

addActionListener(new ActionListener() {
 @Override
 public void actionPerformed(ActionEvent e) {
  System.out.println("isShowingPopup: " + isShowingPopup);
  if (isShowingPopup) {
   isShowingPopup = false;
  } else {
   Component c = (Component) e.getSource();
   menu.show(c,-1,c.getHeight());
   isShowingPopup = true;
  }
 }
});

我现在已经用这个太久了.如果有人能给我一个关于这个问题的线索,那就太好了！

谢谢！

码：

public class Button extends JButton {

    // Icon.
    private static final ImageIcon ARROW_SOUTH = new ImageIcon("ArrowSouth.png");

    // Unit popup menu.
    private final JPopupMenu menu;

    // Is the popup showing or not?
    private boolean isShowingPopup = false;

    public Button(int height) {
        super(ARROW_SOUTH);
        menu = new JPopupMenu(); // menu is populated somewhere else

        // FocusListener on the JPopupMenu
        menu.addFocusListener(new FocusListener() {
            @Override
            public void focusLost(FocusEvent e) {
                System.out.println("LOST FOCUS");
                isShowingPopup = false;
            }

            @Override
            public void focusGained(FocusEvent e) {
                System.out.println("GAINED FOCUS");
            }
        });

        // ComponentListener on the JPopupMenu
        menu.addComponentListener(new ComponentListener() {
            @Override
            public void componentShown(ComponentEvent e) {
                System.out.println("SHOWN");
            }

            @Override
            public void componentResized(ComponentEvent e) {
                System.out.println("RESIZED");
            }

            @Override
            public void componentMoved(ComponentEvent e) {
                System.out.println("MOVED");
            }

            @Override
            public void componentHidden(ComponentEvent e) {
                System.out.println("HIDDEN");
            }
        });

        // ActionListener on the JButton
        addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("isShowingPopup: " + isShowingPopup);
                if (isShowingPopup) {
                    menu.requestFocus();
                    isShowingPopup = false;
                } else {
                    Component c = (Component) e.getSource();
                    menu.show(c,c.getHeight());
                    isShowingPopup = true;
                }
            }
        });

        // Skip when navigating with TAB.
        setFocusable(true); // Was false first and should be false in the end.

        menu.setFocusable(true);
    }

}