Android如何简单快速实现RecycleView的拖动重排序功能

interface ItemTouchHelperAdapter {
    fun onItemMove(fromPosition: Int, toPosition: Int)
}

import androidx.recyclerview.widget.RecyclerView
import java.util.*

class MyAdapter(private val items: MutableList<String>) : RecyclerView.Adapter<MyAdapter.ViewHolder>(), ItemTouchHelperAdapter {

    // ... ViewHolder and other methods ...

    override fun onItemMove(fromPosition: Int, toPosition: Int) {
        if (fromPosition < toPosition) {
            for (i in fromPosition until toPosition) {
                Collections.swap(items, i, i + 1)
            }
        } else {
            for (i in fromPosition downTo toPosition + 1) {
                Collections.swap(items, i, i - 1)
            }
        }
        notifyItemMoved(fromPosition, toPosition)
    }
}

class SimpleItemTouchHelperCallback(private val adapter: ItemTouchHelperAdapter) : ItemTouchHelper.Callback() {

    override fun isLongPressDragEnabled() = true

    override fun isItemViewSwipeEnabled() = false

    override fun getMovementFlags(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder): Int {
    	//这里是水平拖动
        val dragFlags = ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT
        return makeMovementFlags(dragFlags, 0)
    }

    override fun onMove(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder): Boolean {
        adapter.onItemMove(viewHolder.adapterPosition, target.adapterPosition)
        return true
    }

    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
        // do nothing
    }
}

ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT

ItemTouchHelper.UP or ItemTouchHelper.DOWN

val adapter = MyAdapter(myDataset)
val recyclerView = findViewById<RecyclerView>(R.id.my_recycler_view)
recyclerView.adapter = adapter

val callback = SimpleItemTouchHelperCallback(adapter)
val touchHelper = ItemTouchHelper(callback)
touchHelper.attachToRecyclerView(recyclerView)