How do I hide a menu item in the actionbar?

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

Found an addendum to this question:

If you want to change the visibility of your menu items on the go you just need to set a member variable in your activity to remember that you want to hide the menu and call invalidateOptionsMenu() and hide the items in your overridden onCreateOptionsMenu(...) method.

//anywhere in your code...mState = HIDE_MENU; // setting stateinvalidateOptionsMenu(); // now onCreateOptionsMenu(...) is called again...@Overridepublic boolean onCreateOptionsMenu(Menu menu){    // inflate menu from xml    MenuInflater inflater = getSupportMenuInflater();    inflater.inflate(R.menu.settings, menu);    if (mState == HIDE_MENU)    {        for (int i = 0; i < menu.size(); i++)            menu.getItem(i).setVisible(false);    }}

In my example I've hidden all items.

Yes.

1. You can set a flag/condition.
2. Call invalidateOptionsMenu() when you want to hide the option. This will call onCreateOptionsMenu().
3. In onCreateOptionsMenu(), check for the flag/condition and show orhide it the following way:

MenuItem item = menu.findItem(R.id.menu_Done);if (flag/condition)) {  item.setVisible(false); } else { }