当只有一个内容时，将recyclerview项目对齐到顶部

LinearLayoutManager layoutManager = new LinearLayoutManager(context);
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);

public class TopSpaceItemDecoration extends RecyclerView.ItemDecoration {
    private int topSpace;

    public TopSpaceItemDecoration(int topSpace) {
        this.topSpace = topSpace;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (parent.getChildAdapterPosition(view) == 0) {
            outRect.top = topSpace;
        }
    }
}

int topSpace = getResources().getDimensionPixelSize(R.dimen.top_space);
TopSpaceItemDecoration itemDecoration = new TopSpaceItemDecoration(topSpace);
recyclerView.addItemDecoration(itemDecoration);