Android: When Is Oncreateoptionsmenu Called During Activity Lifecycle

Android: When is onCreateOptionsMenu called during Activity lifecycle?

The onCreate method is called first, and before it finishes onCreateOptionsMenu is called.

That will be true on devices and apps with an official Honeycomb-style action bar. If there is no action bar, onCreateOptionsMenu() should not get called until the user calls up the menu, typically by pressing the MENU button.

(I'm using screen size to determine this, my layout file for large screens has a View I check for after the layout is inflated)

That test will break very shortly, once Ice Cream Sandwich ships. From what I can tell, ICS phones will have action bars (though perhaps not system bars).

onCreateOptionsMenu(Menu menu) only gets called once during the lifecycle of an Activity

Yes. To do that you need to use:

public boolean onPrepareOptionsMenu (Menu menu) 

That code will be executed every time before your options menu is shown.
More information here.

Why is onCreateOptionsMenu() called in each fragment using FragmentTransaction add() method?

If you call:

ft.add(R.id.container, fragmentA, "tag").addToBackStack(null).commit();

FragmentA will stay "resumed" and its menu will be "inflated". Then if you call:

ft.add(R.id.container, fragmentB, "tag").addToBackStack(null).commit();

FragmentA is still "resumed" and now FragmentB is also on state "resumed" and its menu will be also "inflated".

When you need to update a view you should use view.invalidate(), and this method will "redraw" the view.

Said so...

If your MainActivity has a menu, it will call invalidateOptionsMenu() to redraw MainActivity's menu and also draw FragmentA's menu. After adding FragmentB the toolbar needs to add its menu, so it will call invalidateOptionsMenu() to redraw MainActivity and FragmentA menu and also draw FragmentB's menu. That's why it's called every time you change Fragment, because the menu view needs to be redrawn.

That does not happen if you use

ft.replace(...)

because the first Fragment will be destroyed.

Hope It helps understand.

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Log your MainActivity's onCreateOptionsMenu and also will be called every time you add a Fragment which has menu.

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