Android Recyclerview GridLayoutManager column spacing

http://stackoverflow.com/questions/28531996/android-recyclerview-gridlayoutmanager-column-spacing

RecyclerViews support the concept of ItemDecoration:
special offsets and drawing around each element. As seen in this answer, you can use

public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private int space;

public SpacesItemDecoration(int space) {
this.space = space;
}

@Override
public void getItemOffsets(Rect outRect, View view,
RecyclerView parent, RecyclerView.State state) {
outRect.left = space;
outRect.right = space;
outRect.bottom = space;

// Add top margin only for the first item to avoid double space between items
if (parent.getChildLayoutPosition(view) == 0) {
outRect.top = space;
} else {
outRect.top = 0;
}
}
}

Then add it via

mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
int spacingInPixels = getResources().getDimensionPixelSize(R.dimen.spacing);
mRecyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels));