android - Reason for NullPointerException if setContentView() is not used

Question

I know that we need to place setContentView() in the onCreate() method before initializing any view otherwise it will throw a null pointer exception. But what is the reason for it?Is the setContentView() similar to the inflate() method?

Answer 1

before initializing any view

I do not know for certain what you mean by "initializing any view". Given the rest of your question, I am going to interpret this as meaning "call findViewById() on the activity".

You need to call setContentView() before calling findViewById(), because otherwise there are no widgets to find.

Is the setContentView() similar to the inflate() method?

setContentView() will use a LayoutInflater and inflate() under the covers, if you pass a layout resource ID into the setContentView() method.