RecyclerView：使用自定义 ItemDecoration 为最后一个项目添加底部间距不适用于 DividerItemDecoration 和 ItemTouchHelper

Question

I am adding a space below the last item in the RecyclerView using this popular and efficient solution:

class ListMarginDecorator(
        private val left: Int = 0,
        private val top: Int = 0,
        private val right: Int = 0,
        private val bottom: Int = 0,
) : RecyclerView.ItemDecoration() {
    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        super.getItemOffsets(outRect, view, parent, state)
        val position = parent.getChildAdapterPosition(view)

        outRect.left = left
        outRect.top = if (position == 0) top else 0
        outRect.right = right
        outRect.bottom = if (position == state.itemCount - 1) bottom else 0
    }
}

I also add item dividers using DividerItemDecoration , and enable drag-to-reorder by implementing ItemTouchHelper .

Here is how I use these ItemDecorators in the fragment class:

binding.recyclerView.addItemDecoration(
    DividerItemDecoration(
            binding.rvCurrencies.context,
            DividerItemDecoration.VERTICAL
    )
)

binding.recyclerView.addItemDecoration(
    ListMarginDecorator(
        bottom = resources.getDimensionPixelSize(R.dimen.list_last_item_bottom_margin) // = 88dp
    )
)

I see two issues with this approach to space under the last item though.

The first is that ListMarginDecorator seems to be applying padding, not margin, so the bottom divider line for the last item in the list is drawn below the spacing that is applied to that last item.

The second issue is that I can no longer drag an item in the list to the bottom-most position.

When I comment out the line adding the ListMarginDecorator though, both of these work as expected:

Is there any other way to efficiently add a space under the last item, without running into these issues?

Answer 1

If you want space after the last item, why don't just use

rvCurrencies.setPadding(0, 0, 0, 100)
rvCurrencies.clipToPadding = false

or in XML

android:paddingBottom="100dp"
android:clipToPadding="false"

in this way, your all two problems will be sorted out.