没有JMenuBar的下拉菜单

Question

有没有办法在Java中实现下拉按钮，但没有实现JMenuBar？ 我需要导入一个带弹出菜单的按钮。我怎么能这样做？

Answer 1

正如@DavidKroukamp所说，JPopupMenu可以做到这一点。

Answer 2

    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;

    import javax.swing.JPopupMenu;
    import javax.swing.JToggleButton;
    import javax.swing.event.PopupMenuEvent;
    import javax.swing.event.PopupMenuListener;

    public class MenuButton extends JToggleButton {

        JPopupMenu popup;

        public MenuButton(String name, JPopupMenu menu) {
            super(name);
            this.popup = menu;
            addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent ev) {
                    JToggleButton b = MenuButton.this;
                    if (b.isSelected()) {
                        popup.show(b, 0, b.getBounds().height);
                    } else {
                        popup.setVisible(false);
                    }
                }
            });
            popup.addPopupMenuListener(new PopupMenuListener() {
                @Override
                public void popupMenuWillBecomeVisible(PopupMenuEvent e) {}
                @Override
                public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
                    MenuButton.this.setSelected(false);
                }
                @Override
                public void popupMenuCanceled(PopupMenuEvent e) {}
            });
        }
    }