What is the difference between onCreateOptionsMenu(Menu menu) and onPrepareOptionsMenu(Menu menu)?

Question

Explain difference between onCreateOptionsMenu(Menu menu) and onPrepareOptionsMenu(Menu menu).

Answer 1

onCreateOptionsMenu() is called once.
onPrepareOptionsMenu() is called every time the menu opens.

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From the onCreateOptionsMenu() documentation:

This is only called once, the first time the options menu is displayed. To update the menu every time it is displayed, see onPrepareOptionsMenu(Menu).