Confusing Android Activity lifecycle bahavior

Question

Hello,

I did a simple program by overriding each of the lifecycle methods and everything works as I'd expect, except for onRestoreInstanceState(Bundle savedInstanceState).

I overrode the method as

@Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);   
    Toast.makeText(getBaseContext(), "onRestoreInstanceState - Activity1 ", Toast.LENGTH_SHORT).show();
    }

But it never gets called.

I overrode onSaveInstanceState(Bundle outState) too and I can see the system calling it, but never the onRestoreInstanceState(Bundle savedInstanceState). When I press back button or so, I can see that the system calls onRestore(), OnStart() and onResume(), and the UI (just two buttons) are displayed correctly.

How is it possible that the UI is restored without calling onRestoreInstanceState(Bundle savedInstanceState)? I only do setContentView(R.layout.main) is onCreate(savedInstanceState). So how does it restore the UI without calling either onCreate() or onRestoreInstanceState()?

Would really appreciate somebody shedding some light on this.

Thank you.