Android :: Can Hook Methods Called By System / Ever Be Passed In Null Argument Reference?

While doing normal day-to-day Android development, is it safe to assume that hook methods called by the system will not pass in invalid references (ex.: null), or should I always be double-checking what arguments get passed in?For example, can the method onOptionsItemSelected(MenuItem) ever have a null MenuItem reference passed into it?The reason I ask is because I was working on the Notepad 1 tutorial,I started wondering if I should be testing if item is null before making a getItemId() method call on it, or just trust the system to not ever pass me a null?I don't want to make my code slower by doing null checks when I shouldn't be worried about that happening, etc.