Why getContext() in fragment sometimes returns null?

Question

Why getContext() sometimes returns null? I pass context to LastNewsRVAdapter.java as an argument. But LayoutInflater.from(contex

Answer 1

First of all, as you can see on this link, the method onCreateView() inside the fragment's lifecycle comes after onAttach(), so you should have already a context at that point. You may wonder, why does getContext() return null then? the problem lies on where you are creating your adapter:

App.getApiService().getLatestNews().enqueue(new Callback() {
        @Override
        public void onResponse(Call call, Response response) {
            if (response.isSuccessful() && response.body().isSuccessfull()){
                adapter = new LastNewsRVAdapter(getContext(), response.body().getData(), sideBanner);
                rvLatestNews.setAdapter(adapter);
                tvSonkuKabar.setVisibility(View.VISIBLE);
            }
        }

        @Override
        public void onFailure(Call call, Throwable t) {

        }
    });

Though you are specifying a callback in onCreateView(), that does not mean the code inside that callback will run at that point. It will run and create the adapter after the network call is done. With that in mind, your callback may run after that point in the lifecycle of the fragment. What I mean is that the user can enter that screen (fragment) and go to another fragment or return to the previous one before the network request finishes (and the callback runs). If that happens, then getContext() could return null if the user leaves the fragment (onDetach() may have been called).

Besides, you can have memory leaks also, in case the activity is destroyed before your network request finishes. So you have two issues there.

My suggestions to solve those issues are:

1. in order to avoid the null pointer exception and the memory leak, you should cancel the network request when the onDestroyView() inside the fragment is being called (retrofit returns an object that can cancel the request: link).

2. Another option that will prevent the null pointer exception is to move the creation of the adapter LastNewsRVAdapter outside the callback and keep a reference to it in the fragment. Then, use that reference inside the callback to update the content of the adapter: link