Hiding menu items in Jface MenuManager and TreViewer

问题

I want to hide all popup menu items when I click on any node that is not "Item1", but the items are not being hidden, why?
(The manager.getItems()[i].setVisible(false) inside loop is triggered)

Action a1 = new Action("XXX") {};
Action a2 = new Action("YYY") {};
Action a3 = new Action("ZZZ") {};

final MenuManager mgr = new MenuManager();


mgr.add(a1);
mgr.add(a2);
mgr.add(a3);

mgr.addMenuListener(new IMenuListener() {
        public void menuAboutToShow(IMenuManager manager) {
            IStructuredSelection selection = (IStructuredSelection) tree
                    .getSelection();
            if (!selection.isEmpty()) {
                String str = ((MyModel) selection.getFirstElement())
                        .toString();
                if (str.equals("Item1")) {
                    for (int i = 0; i < 3; i++) {
                        manager.getItems()[i].setVisible(true);
                    }
                } else {
                    for (int i = 0; i < 3; i++) {
                        manager.getItems()[i].setVisible(false);
                    }
                }
            }
        }
    });

When first I click on Item (str.equals("Item1")), clicking on other items don't hide the menu items.

回答1:

You have to call manager.update(true); after setting the visibility of your menu items to make the MenuManager update the underlying Menu widget.

回答2:

Yes, you can do something like

for(val menuItem : menu.getItems()){
    menuItem.setVisible(yourCondition);
}
menu.update(true);

I've tested it.

来源：https://stackoverflow.com/questions/7825162/hiding-menu-items-in-jface-menumanager-and-treviewer