我需要一個帶有附加下拉樣式菜單的JButton.所以我拿了一個JPopupMenu并以你在下面的代碼中看到的方式將它附加到JButton.它需要做的是：

>單擊時顯示彈出窗口

>如果再次點擊,請隱藏它

>如果在彈出窗口中選擇了某個項目,則將其隱藏

>如果用戶點擊屏幕中的其他位置,則隱藏它

這4件事情都有效,但由于我正在使用的布爾標志,如果用戶點擊其他地方或選擇了一個項目,我必須在按鈕上單擊兩次才會再次顯示.這就是為什么我試圖添加一個FocusListener(絕對沒有響應)來修復它并在這些情況下將標志設置為false.

編輯：最后一次嘗試回答帖子……

以下是監聽器:(它在一個擴展JButton的類中,所以第二個監聽器在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;

}

}

});

我現在已經用這個太久了.如果有人能給我一個關于這個問題的線索,那就太好了！

謝謝！

碼：

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, -1, c.getHeight());

isShowingPopup = true;

}

}

});

// Skip when navigating with TAB.

setFocusable(true); // Was false first and should be false in the end.

menu.setFocusable(true);

}

}

總結

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