Dynamically set span count in an Android RecyclerView's GridLayoutManager. Implementation is taken from a Fragment.

GridFragment.java

private RecyclerView mRecyclerView;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_view, container, false);
    mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
    // ommiting other recycler view set up, such as adapter and Layout manager set up ..
    ViewTreeObserver viewTreeObserver = mRecyclerView.getViewTreeObserver();
    viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            calculateCellSize();
        }
    });
}

private static final int sColumnWidth = 120; // assume cell width of 120dp
private void calculateSize() {
    int spanCount = (int) Math.floor(mRecyclerView.getWidth() / convertDPToPixels(sColumnWidth));
    ((GridLayoutManager) mRecyclerView.getLayoutManager()).setSpanCount(spanCount);
}

private float convertDPToPixels(int dp) {
    DisplayMetrics metrics = new DisplayMetrics();
    getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
    float logicalDensity = metrics.density;
    return dp * logicalDensity;
}