Fragments onCreateView() bundle. Where does it come from?

I'm starting an Activity through the usual means:

Intent startIntent = new Intent(this, DualPaneActivity.class);
startIntent.putExtras(((SearchPageFragment) currentFragment).getPageState());
startActivity(startIntent);

When this activity loads, it places a Fragment in a frame like so:

FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();   
Fragment currentFragment = fragment;
currentFragment.setArguments(getIntent().getExtras());开发者_运维百科
transaction.replace(R.id.singlePane, currentFragment);  
transaction.commit();

Seems simple, right?

However, you can inside of onCreateView() method access three separate bundles (four, if you include the one included in the Fragment's onCreate(Bundle savedInstanceState)):

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
{
    // Fill state information
    Bundle bundle;
    if(savedInstanceState != null)  bundle = savedInstanceState; // 1       
    else if(getArguments() != null) bundle = getArguments();     // 2
    else                            bundle = getActivity().getIntent().getExtras(); // 3
    setPageState(bundle);   
}

In the above instance, I've worked out from trial and error that the bundle I want is the second one, the one retrieved from getArguments().

From my understanding the third one from getActivity().getIntent().getExtras(); is actually calling the Bundle from the intent used to start containing activity. I also know from experimentation that savedInstanceState seems to always be null. But where is it coming from and why is it null?

The documentation says this:

savedInstanceState If non-null, this fragment is being re-constructed from a previous saved state as given here.

That doesn't help me - It's bugging me more than stopping me from moving on. Can someone help me out with this annoyance?

To the best of my knowledge, onCreateView and onCreate() are both passed the bundle from onSaveInstanceState().

So if you override onSaveInstanceState() and put data in the bundle, you should be able to retrieve it in onCreateView(). That is why the documentation says that the bundle will be non-null when the fragment is re-constructed from a previous saved state.