Android Fragment Is Given A Null Container In Oncreateview()

I am trying to use Android fragments in a very simple way, similar to the tutorial on the Android developer website. I have an Activity (MediaInfoActivity) with the following code:

Solution 1:

You just have to create a inflater like bellow in your fragment.

View rootView;
 publicViewonCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    if (rootView == null) {
        rootView = inflater.inflate(R.layout.activity_my_cart, null);
    } else {
        ((ViewGroup) container.getParent()).removeView(rootView);
    }
    return rootView;
}

I hope it will work as per your question.

Solution 2:

I am not sure since I don't have the code of the SDK in front of me but I think that the life-cycle of calling Fragment "onCreateView" function is different between the two cases: 1. Static settings of fragment in layout 2. Loading pragmatically with FragmentManager.

In the first case the debugger get into Fragment.onCreateView() method immediately upon adding the content view to the parent activity as part of onCreate() code:

When calling: setContentView(R.layout.some_layoue); You will see the debugger get into Fragment.onCreateView() before going to next line

In the second case the Fragment.onCreateView() is being invoked only after the onCreate() of the activity is finished.

This looks like design bug for me but possibly as design feature. Anyway the container is null when adding fragment statically because the related object was not yet created.

In fact the difference between the two situations is much deeper. In the case of static fragments toggling between fragments will not create the view hierarchy correctly.

For example if you will add button-A to fragment A and button-B to Fragment-B and toggle the fragments with a code looks like this (highlighting only the relevant code):

publicvoidturnOnFragment() {
    FragmentManager manager = getFragmentManager();
    if (manager != null) {
        manager.beginTransaction()
                .setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
                .attach(this)
                .commit();
    }
}



publicvoidturnOffFragment() {
    FragmentManager manager = getFragmentManager();
    if (manager != null) {
        manager.popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
        manager.beginTransaction()
                .setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
                .detach(this)
                .commit();


    }
}

You will see that in the case of static fragments the buttons from both fragments are presented although turning on and off. If however fragments are added programatically the toggle works fine and view hierarchy is cleaned and show only button from relevant fragment.

This is based of my experience with version 4.4.2