Android reverse shared element transition on back after orientation change?

Question

For shared element transition I am following this github project. It has 2 screens - one with recyclerview having number of cards & second the detail screen. As expected

Answer 1

I came across this same problem and this how I fixed it.

When the RecyclerView item is clicked, I pass the current position:

@Override
public void onItemClick(View sharedView, String transitionName, int position) {
    viewPosition = position;
    Intent intent = new Intent(this, TransitionActivity.class);
    intent.putExtra("transition", transitionName);
    ActivityOptionsCompat options = ActivityOptionsCompat.
            makeSceneTransitionAnimation(this, sharedView, transitionName);
    ActivityCompat.startActivity(this, intent, options.toBundle());
}

I save it in onSaveInstanceState to persist across configuration changes:

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt(VIEW_POSITION, viewPosition);
}

Then, in the onCreate method:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Workaround for orientation change issue
    if (savedInstanceState != null) {
        viewPosition = savedInstanceState.getInt(VIEW_POSITION);
    }

    setExitSharedElementCallback(new SharedElementCallback() {
        @Override
        public void onMapSharedElements(List names, Map sharedElements) {
            super.onMapSharedElements(names, sharedElements);
            if (sharedElements.isEmpty()) {
                View view = recyclerView.getLayoutManager().findViewByPosition(viewPosition);
                if (view != null) {
                    sharedElements.put(names.get(0), view);
                }
            }
        }
    });
}

Cause of the problem: the sharedElements map was empty (I don't know why) after the orientation change.