如何从其他活动中更改menuitem的可见性？

can anybody tell me how to change the visibility of a menuitem from another activity? I have two activities "activity A and B". in one activity A when I press a menu item it saves some strings to the list of activity B and In activity A menuitem visibility set to false. now I want that when I delete that item from activity B which I saved from activity A, with this delete the menuitem visibility in activity A changes to true and it become visible again? so how can I do this. I using database to populate listview.can anybody tell me how to change the visibilit