Android使用gridlayoutmanager在recyclerview的最后一个元素下面添加间距

Question

我正在尝试使用GridLayoutManager在RecyclerView中的最后一个元素行下面添加间距。为此，我使用了自定义的itemderection并在其最后一个元素时进行底部填充，如下所示：

public class SpaceItemDecoration extends RecyclerView.ItemDecoration {
private int space;
private int bottomSpace = 0;

public SpaceItemDecoration(int space, int bottomSpace) {
    this.space = space;
    this.bottomSpace = bottomSpace;
}

public SpaceItemDecoration(int space) {
    this.space = space;
    this.bottomSpace = 0;
}

@Override
public void getItemOffsets(Rect outRect, View view,
                           RecyclerView parent, RecyclerView.State state) {

    int childCount = parent.getChildCount();
    final int itemPosition = parent.getChildAdapterPosition(view);
    final int itemCount = state.getItemCount();

    outRect.left = space;
    outRect.right = space;
    outRect.bottom = space;
    outRect.top = space;

    if (itemCount > 0 && itemPosition == itemCount - 1) {
        outRect.bottom = bottomSpace;
    }
}
}

这将对LinearLayoutManager正确工作。只是在GridLayoutManager的情况下，它是有问题的。

如果底部有fab并且需要最后一行中的项目滚动到fab上方，以便它们可见，那么它非常有用。

Answer 1

这个问题的解决方案在于覆盖GridLayoutManager的SpanSizeLookup。

您必须对活动或片段中的GridlayoutManager进行更改，在这些活动或片段中您正在膨胀RecyLerView。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //your code 
    recyclerView.addItemDecoration(new PhotoGridMarginDecoration(context));

    // SPAN_COUNT is the number of columns in the Grid View
    GridLayoutManager gridLayoutManager = new GridLayoutManager(context, SPAN_COUNT);

    // With the help of this method you can set span for every type of view
    gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            if (list.get(position).getType() == TYPE_HEADER) {
                // Will consume the whole width
                return gridLayoutManager.getSpanCount();
            } else if (list.get(position).getType() == TYPE_CONTENT) {
                // will consume only one part of the SPAN_COUNT
                return 1;
            } else if(list.get(position).getType() == TYPE_FOOTER) {
                // Will consume the whole width
                // Will take care of spaces to be left,
                // if the number of views in a row is not equal to 4
                return gridLayoutManager.getSpanCount();
            }
            return gridLayoutManager.getSpanCount();
        }
    });
    recyclerView.setLayoutManager(gridLayoutManager);
}