android - Scroll to top in RecyclerView with LinearLayoutManager

Question

I have a fragment in which there is RecyclerView with LinearLayoutManager in which there are CardView items. There is a floating action button on clicking which the items should scroll to top. I have tried using scrollToPosition as well as scrollToPositionWithOffset with RecyclerView and also with LinearLayoutManager as shown below. But it has no effect at all. Why is this so? Can anyone please help me out.

And i have placed the RecyclerView directly inside the SwipeRefreshView in the xml file. I am calling setFloatingActionButton as soon as set adapter to RecyclerView.

 public void setFloatingActionButton(final View view) {
    float = (android.support.design.widget.FloatingActionButton) getActivity().findViewById(R.id.float);
    float.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
    mRecyclerView.smoothScrollToPosition(0);


            android.support.design.widget.Snackbar.make(view, "Scrolled to Top", android.support.design.widget.Snackbar.LENGTH_SHORT)
                    .setAction("Ok", new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            LinearLayoutManager llm = (LinearLayoutManager) mRecyclerView.getLayoutManager();
                            llm.scrollToPosition(0);

                        }
                    })
                    .setActionTextColor(getActivity().getResources().getColor(R.color.coloLink))
                    .show();
        }
    });
}

Answer 1

Continuing from above comments, ideally, replacing

mRecyclerView.smoothScrollToPosition(0);

in the onClick of the floating action button with

mLayoutManager.scrollToPositionWithOffset(0, 0);

should work. You can also remove the SnackBar code, because you don't need it anyways. So, all in all your above method should look like

public void setFloatingActionButton(final View view) {
    float actionButton = (android.support.design.widget.FloatingActionButton) getActivity()
            .findViewById(R.id.float);
    actionButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            LinearLayoutManager layoutManager = (LinearLayoutManager) mRecyclerView
                    .getLayoutManager();
            layoutManager.scrollToPositionWithOffset(0, 0);
        }
    });
}

And if you say that the above doesnt work, then test if the onClick() is even being called or not. Try adding a log message in it and see if its printed.