Very simple code, but got error “Activity has been destroyed” when use Fragment

Question

I made a very simple Activity which shows a simple ListFragment like below:

My Activity:

public class MyActivity ex         


        

Answer 1

super.onCreate(savedInstanceState) will call onCreate method in FragmentActivity, which will call mFragments.attachHost(null /*parent*/);

This sentence will assign a value to mHost in FragmentController, when you calls FragmentTransaction.commit() ,

In the method enqueueAction(),it has this sentences

 if (mDestroyed || mHost == null) {
        throw new IllegalStateException("Activity has been destroyed");
 }

So if you haven't call super.onCreate(savedInstanceState) before you commit a fragmentTransaction, you will get this exception because mHost is null