@TargetApi(Build.VERSION_CODES.LOLLIPOP)
                    @Override
                    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                        if (0 == mRecyclerView.computeVerticalScrollOffset()) {
                            appbarView.setElevation(0);
                        } else {
                            appbarView.setElevation(appbarView.getTargetElevation());
                        }
                    }
DetailFragmentCallback for when an item has been selected.
app/src/main/java/com/example/android/sunshine/app/ForecastFragment.java