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前言

随着需求的变化，很多地方需要加拖动改变顺序的需求，用RecyclerView就可以实现列表拖动排序，列如像朋友圈图片拖动排序，或者音乐播放器列表拖动排序，我这里没有弄GIF图，截图就是正在拖动的效果。

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一、效果图

二、实现步骤

1.xml布局

代码如下（示例）：

 	 <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginLeft="12dp"
        android:layout_marginTop="10dp"
        android:layout_marginRight="5dp"
        android:layout_marginBottom="12dp"
        android:overScrollMode="never" />

2.activity代码

代码如下（示例）：

	private lateinit var list_view: RecyclerView
	private lateinit var listbean: MutableList<String>
	private lateinit var adapter: IntelligentReplyAdapter
	//一排显示多个需要全局定义，不然每次排序后都要加载一次空隙就越来越大，正常列表显示一个不需要定义这个
	private lateinit var itemDecoration: RecyclerView.ItemDecoration

	    itemDecoration = SpacesItemDecoration(20)
		listbean = mutableListOf()
		for (i in 1..6) {
            listbean.add("$i 号回复组名称")
        }
 		list_view = findViewById(R.id.list_view)
        list_view.layoutManager = LinearLayoutManager(
            this,
            LinearLayoutManager.VERTICAL,
            false
        ) //竖向显示
         // 设置LayoutManager为GridLayoutManager，每行3个item -->一排显示多个需要
        //val layoutManager = GridLayoutManager(this, 3)
        //list_view.addItemDecoration(itemDecoration)
        //list_view.layoutManager = layoutManager
        adapter = IntelligentReplyAdapter(listbean, this)
        list_view.adapter = adapter
        //RecyclerView实现拖拽实现 设置ItemTouchHelper
        val callback: ItemTouchHelper.Callback = object : ItemTouchHelper.Callback() {
            override fun getMovementFlags(
                recyclerView: RecyclerView,
                viewHolder: RecyclerView.ViewHolder
            ): Int {
                val dragFlags =
                    ItemTouchHelper.UP or ItemTouchHelper.DOWN or ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT
                return makeMovementFlags(dragFlags, 0) // 允许上下左右拖拽
            }

            override fun onMove(
                recyclerView: RecyclerView,
                viewHolder: RecyclerView.ViewHolder,
                target: RecyclerView.ViewHolder
            ): Boolean {
                val toPositioncc = viewHolder.adapterPosition
                // 检查目标位置是否是最后一个位置
                if (toPositioncc == (adapter.itemCount - 1)) {
                    return false // 不允许移动到最后一个位置
                }
                val toPosition = viewHolder.adapterPosition
                val fromPosition = target.adapterPosition
                // 交换数据集中的元素位置
                Collections.swap(listbean, fromPosition, toPosition)
                // 通知Adapter数据已更改
                adapter.notifyItemMoved(fromPosition, toPosition)
                return true
            }

            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
                // 不处理滑动事件，如果需要可以处理删除逻辑
            }
        }
        val itemTouchHelper = ItemTouchHelper(callback)
        itemTouchHelper.attachToRecyclerView(list_view)

3.adapter

代码如下（item的xml布局就补贴了）：

/**
 * 作者：CaoLiulang
 * ❤
 * Date：2024/12/24
 * ❤
 * 模块 智能回复adapter
 */
public class IntelligentReplyAdapter extends RecyclerView.Adapter<IntelligentReplyAdapter.ViewHolder> {
    private List<String> list;
    private Context context;


    public IntelligentReplyAdapter(List<String> list, Context context) {
        this.list = list;
        this.context = context;
    }

    /**
     * 加载更多
     *
     * @param mPageList
     */
    public void setData(List<String> mPageList) {
        try {
            if (mPageList != null) {
                int previousSize = 0;
                try {
                    previousSize = list.size();
                } catch (Exception e) {
                    previousSize = 0;
                }
                int sizez = previousSize + 2;
                list.addAll(mPageList);
                notifyItemRangeInserted(sizez, mPageList.size());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.intelligentreply_item, parent, false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }

    /**
     * 类似GetView
     *
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(final ViewHolder holder, @SuppressLint("RecyclerView") final int position) {
        holder.text_name.setText(list.get(position));
    }

    //添加元素,需要告诉UI线程布局的变动
    public void update() {
        notifyDataSetChanged();
    }

    /**
     * 长度
     *
     * @return
     */
    @Override
    public int getItemCount() {
        return list.size();
    }

    /**
     * 初始化组件
     */
    class ViewHolder extends RecyclerView.ViewHolder {

        TextView text_name;
        public ViewHolder(final View itemView) {
            super(itemView);
            text_name = itemView.findViewById(R.id.text_name);
        }
    }

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总结

实现列表拖拽排序其实很简单，RecyclerView正常加载数据，然后去设置ItemTouchHelper就可以了，是不是很简单呢。