NPE on ButterKnife view references safe callbacks for Fragments.

BaseFragment.java

public abstract class BaseFragment extends Fragment implements ViewableFragment {

    private boolean mHasViews;

    @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(getFragmentLayoutId(), null);
        ButterKnife.inject(this, root);
        return root
    }

    @Override public void onViewStateRestored(Bundle state) {
        super.onViewStateRestored(state);
        mHasViews = true;
    }

    @Override public void onDestroyView() {
        super.onDestroyView();
        ButterKnife.reset(this);
        mHasViews = false;
    }

    @Override public boolean hasViews() {
        return mHasViews;
    }
}

OnPreDrawListenerWrapper.java

public class OnPreDrawListenerWrapper implements ViewTreeObserver.OnPreDrawListener {

    private final ViewTreeObserver.OnPreDrawListener mListener;
    private WeakReference<Fragment> mFragment;

    public OnPreDrawListenerWrapper(Fragment fragment, ViewTreeObserver.OnPreDrawListener listener) {
        mFragment = new WeakReference<>(fragment);
        mListener = listener;
    }

    @Override public boolean onPreDraw() {
        if (canExecute()) {
            return mListener.onPreDraw();
        }
        return true;
    }
    
    private boolean canExecute() {
        return mFragmentRef.get() != null && mFragmentRef.get().hasViews();
    }
}

RunnableWrapper.java

public class RunnableWrapper implements Runnable {

    private final WeakReference<ViewableFragment> mFragmentRef;
    private final Runnable mRunnable;

    public RunnableWrapper(ViewableFragment fragment, Runnable runnable) {
        mFragmentRef = new WeakReference<>(fragment);
        mRunnable = runnable;
    }

    @Override public void run() {
        if (canExecute()) {
            mRunnable.run();
        }
    }

    private boolean canExecute() {
        return mFragmentRef.get() != null && mFragmentRef.get().hasViews();
    }
}

ViewableFragment.java

public interface ViewableFragment {

    boolean hasViews();
}

Why View root = inflater.inflate(getFragmentLayoutId(), null); and not inflater.inflate(getFragmentLayoutId(), container, false); ?

The earliest possible.