Question

I have an action bar with a menuitem. How can I hide/show that menu item?

This is what I’m trying to do:

MenuItem item = (MenuItem) findViewById(R.id.addAction);
item.setVisible(false);
this.invalidateOptionsMenu();

Answer 1

Get a MenuItem pointing to such item, call setVisible on it to adjust its visibility and then call invalidateOptionsMenu() on your activity so the ActionBar menu is adjusted accordingly.

Update: A MenuItem is not a regular view that’s part of your layout. Its something special, completely different. Your code returns null for item and that’s causing the crash. What you need instead is to do:

MenuItem item = menu.findItem(R.id.addAction);

Here is the sequence in which you should call:
first call invalidateOptionsMenu() and then inside onCreateOptionsMenu(Menu) obtain a reference to the MenuItem (by calling menu.findItem()) and call setVisible() on it