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RecycleView拖动效果_可拖拽的recycview

作者：你好赵伟 | 2024-03-22 09:10:55

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可拖拽的recycview

前言：基于RecycleView实现拖动效果，其实很简单，只需使用系统提供的ItemTouchHelper即可满足大部分需求。

实现：

1、创建ItemTouchHelper,在CallBack中处理业务

（1）getMovementFlags()设置允许拖动、滑动的方向

（2）onMove()拖动过程不断调用，用于交换item

（3）onSelectedChanged()长按选中回调，可以用作选中背景高亮

（4）clearView()结束拖动回调，可以用作还原选中背景

2、关联RecycleView，赋予滑动能力

  1. override fun onCreate(savedInstanceState: Bundle?) {
  2.         super.onCreate(savedInstanceState)
  3.         setContentView(R.layout.activity_main)
  4.         val tableList = ArrayList<String>()
  5.         for (i in 1..200) {
  6.             tableList.add("桌（${i}）")
  7.         }
  8.         rv_table.layoutManager = GridLayoutManager(this, 5)
  9.         TableAdapter().let {
  10.             it.mTableList = tableList
  11.             rv_table.adapter = it
  12.         }
  13.         val itemTouchHelper = ItemTouchHelper(object : ItemTouchHelper.Callback() {
  14.             override fun getMovementFlags(
  15.                 recyclerView: RecyclerView,
  16.                 viewHolder: RecyclerView.ViewHolder
  17.             ): Int {
  18.                 //拖动方向
  19.                 val dargFlags =
  20.                     ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT or ItemTouchHelper.UP or ItemTouchHelper.DOWN
  21.                 //滑动方向
  22.                 val swipeFlags = ItemTouchHelper.UP or ItemTouchHelper.DOWN
  23.                 //设置拖动、滑动方向
  24.                 return makeMovementFlags(dargFlags, swipeFlags)
  25.             }
  26.  
  27.             override fun onMove(
  28.                 recyclerView: RecyclerView,
  29.                 viewHolder: RecyclerView.ViewHolder,
  30.                 target: RecyclerView.ViewHolder
  31.             ): Boolean {
  32.                 //拖动的ViewHolder位置
  33.                 val fromPosition = viewHolder.adapterPosition
  34.                 //经过的ViewHolder位置
  35.                 val toPosition = target.adapterPosition
  36.                 when{
  37.                     fromPosition < toPosition -> {//向后拖动,和位置+1进行交换
  38.                         for (i in fromPosition..toPosition) {
  39.                             Collections.swap(tableList, i, i + 1)
  40.                         }
  41.                         recyclerView.adapter?.notifyItemMoved(fromPosition, toPosition)
  42.                     }
  43.                     fromPosition > toPosition -> {//向前拖动,和位置-1进行交换
  44.                         for (i in fromPosition..toPosition) {
  45.                             Collections.swap(tableList, i, i - 1)
  46.                         }
  47.                         recyclerView.adapter?.notifyItemMoved(fromPosition, toPosition)
  48.                     }
  49.                 }
  50.                 return true
  51.             }
  52.  
  53.             override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
  54.                 super.onSelectedChanged(viewHolder, actionState)
  55.                 //长按选中更新要拖动的ViewHolder背景色
  56.                 (viewHolder as? TableAdapter.TableViewHolder)?.tvTabe?.setBackgroundResource(R.color.colorPrimary)
  57.             }
  58.  
  59.             override fun clearView(
  60.                 recyclerView: RecyclerView,
  61.                 viewHolder: RecyclerView.ViewHolder
  62.             ) {
  63.                 super.clearView(recyclerView, viewHolder)
  64.                 (viewHolder as TableAdapter.TableViewHolder).tvTabe.setBackgroundResource(R.color.colorAccent)
  65.             }
  66.             override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {}
  67.         })
  68.         //赋予RecycleView拖动能力
  69.         itemTouchHelper.attachToRecyclerView(rv_table)
  70.     }

进阶

场景一：禁止部分item拖动（如第1项禁止拖动）

1、禁用默认的拖动：CallBack中isLongPressDragEnabled()返回false

2、在自定义实现的item长按事件里，对于满足条件的执行拖动操作

  1. override fun onCreate(savedInstanceState: Bundle?) {
  2.         super.onCreate(savedInstanceState)
  3.         setContentView(R.layout.activity_main)
  4.         val tableList = ArrayList<String>()
  5.         for (i in 1..200) {
  6.             tableList.add("桌（${i}）")
  7.         }
  8.         rv_table.layoutManager = GridLayoutManager(this, 5)
  9.         val itemTouchHelper = ItemTouchHelper(object : ItemTouchHelper.Callback() {
  10.             override fun getMovementFlags(
  11.                 recyclerView: RecyclerView,
  12.                 viewHolder: RecyclerView.ViewHolder
  13.             ): Int {
  14.                 //拖动方向
  15.                 val dargFlags =
  16.                     ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT or ItemTouchHelper.UP or ItemTouchHelper.DOWN
  17.                 //滑动方向
  18.                 val swipeFlags = ItemTouchHelper.UP or ItemTouchHelper.DOWN
  19.                 //设置拖动、滑动方向
  20.                 return makeMovementFlags(dargFlags, swipeFlags)
  21.             }
  22.  
  23.             override fun onMove(
  24.                 recyclerView: RecyclerView,
  25.                 viewHolder: RecyclerView.ViewHolder,
  26.                 target: RecyclerView.ViewHolder
  27.             ): Boolean {
  28.                 //拖动的ViewHolder位置
  29.                 val fromPosition = viewHolder.adapterPosition
  30.                 //经过的ViewHolder位置
  31.                 val toPosition = target.adapterPosition
  32.                 when{
  33.                     fromPosition < toPosition -> {//向后拖动,和位置+1进行交换
  34.                         for (i in fromPosition..toPosition) {
  35.                             Collections.swap(tableList, i, i + 1)
  36.                         }
  37.                         recyclerView.adapter?.notifyItemMoved(fromPosition, toPosition)
  38.                     }
  39.                     fromPosition > toPosition -> {//向前拖动,和位置-1进行交换
  40.                         for (i in fromPosition..toPosition) {
  41.                             Collections.swap(tableList, i, i - 1)
  42.                         }
  43.                         recyclerView.adapter?.notifyItemMoved(fromPosition, toPosition)
  44.                     }
  45.                 }
  46.                 return true
  47.             }
  48.  
  49.             override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
  50.                 super.onSelectedChanged(viewHolder, actionState)
  51.                 //长按选中更新要拖动的ViewHolder背景色
  52.                 (viewHolder as? TableAdapter.TableViewHolder)?.tvTabe?.setBackgroundResource(R.color.colorPrimary)
  53.             }
  54.  
  55.             override fun clearView(
  56.                 recyclerView: RecyclerView,
  57.                 viewHolder: RecyclerView.ViewHolder
  58.             ) {
  59.                 super.clearView(recyclerView, viewHolder)
  60.                 (viewHolder as TableAdapter.TableViewHolder).tvTabe.setBackgroundResource(R.color.colorAccent)
  61.             }
  62.  
  63.             override fun isLongPressDragEnabled(): Boolean {
  64.                 //禁用默认拖动
  65.                 return false
  66.             }
  67.             override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {}
  68.         })
  69.         //赋予RecycleView滑动能力
  70.         itemTouchHelper.attachToRecyclerView(rv_table)
  71.         TableAdapter().let {
  72.             it.mTableList = tableList
  73.             rv_table.adapter = it
  74.             //将拖动职能传递给Adapter
  75.             it.mItemTouchHelper = itemTouchHelper
  76.         }
  77.     }

  1. class TableAdapter : RecyclerView.Adapter<TableAdapter.TableViewHolder>(){
  2.     var mTableList = ArrayList<String>()
  3.     var mItemTouchHelper: ItemTouchHelper? = null
  4.  
  5.     override fun getItemCount(): Int {
  6.         return mTableList.size
  7.     }
  8.  
  9.     override fun onBindViewHolder(holder: TableViewHolder, position: Int) {
  10.         val table = mTableList[position]
  11.         holder.tvTabe.text = table
  12.     }
  13.  
  14.     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TableViewHolder {
  15.         val view = LayoutInflater.from(parent.context).inflate(R.layout.item_table, parent, false)
  16.         return TableViewHolder(view)
  17.     }
  18.  
  19.     inner class TableViewHolder constructor(view: View): RecyclerView.ViewHolder(view) {
  20.         val tvTabe = view.findViewById<TextView>(R.id.tv_table)
  21.  
  22.         init {
  23.             tvTabe.setOnLongClickListener {
  24.                 if (this.adapterPosition != 0){
  25.                     mItemTouchHelper?.startDrag(this)
  26.                     return@setOnLongClickListener true
  27.                 }
  28.                 return@setOnLongClickListener false
  29.             }
  30.         }
  31.     }
  32. }

场景二：只需将拖动的item和最终位置item进行交换，途径位置保持不变

1、在onMove()中将经过的位置记录到拖动的ViewHolder中

2、在clearView()中进行位置交换

  1. override fun onCreate(savedInstanceState: Bundle?) {
  2.         super.onCreate(savedInstanceState)
  3.         setContentView(R.layout.activity_main)
  4.         val tableList = ArrayList<String>()
  5.         for (i in 1..200) {
  6.             tableList.add("桌（${i}）")
  7.         }
  8.         rv_table.layoutManager = GridLayoutManager(this, 5)
  9.         val itemTouchHelper = ItemTouchHelper(object : ItemTouchHelper.Callback() {
  10.             override fun getMovementFlags(
  11.                 recyclerView: RecyclerView,
  12.                 viewHolder: RecyclerView.ViewHolder
  13.             ): Int {
  14.                 //拖动方向
  15.                 val dargFlags =
  16.                     ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT or ItemTouchHelper.UP or ItemTouchHelper.DOWN
  17.                 //滑动方向
  18.                 val swipeFlags = ItemTouchHelper.UP or ItemTouchHelper.DOWN
  19.                 //设置拖动、滑动方向
  20.                 return makeMovementFlags(dargFlags, swipeFlags)
  21.             }
  22.  
  23.             override fun onMove(
  24.                 recyclerView: RecyclerView,
  25.                 viewHolder: RecyclerView.ViewHolder,
  26.                 target: RecyclerView.ViewHolder
  27.             ): Boolean {
  28.                 //经过的ViewHolder位置保存到拖动的ViewHolder中
  29.                 val toPosition = target.adapterPosition
  30.                 (viewHolder as TableAdapter.TableViewHolder).toPosition = toPosition
  31.                 return true
  32.             }
  33.  
  34.             override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
  35.                 super.onSelectedChanged(viewHolder, actionState)
  36.                 //长按选中更新要拖动的ViewHolder背景色
  37.                 (viewHolder as? TableAdapter.TableViewHolder)?.tvTabe?.setBackgroundResource(R.color.colorPrimary)
  38.             }
  39.  
  40.             override fun clearView(
  41.                 recyclerView: RecyclerView,
  42.                 viewHolder: RecyclerView.ViewHolder
  43.             ) {
  44.                 super.clearView(recyclerView, viewHolder)
  45.                 (viewHolder as TableAdapter.TableViewHolder).tvTabe.setBackgroundResource(R.color.colorAccent)
  46.                 //拖动ViewHolder位置
  47.                 val fromPosition = viewHolder.adapterPosition
  48.                 //终点位置
  49.                 val toPosition = viewHolder.toPosition
  50.                 if (toPosition >= 0){
  51.                     Collections.swap(tableList, fromPosition, toPosition)
  52.                     recyclerView.adapter?.let{
  53.                         it.notifyItemChanged(fromPosition)
  54.                         it.notifyItemChanged(toPosition)
  55.                     }
  56.                 }
  57.             }
  58.  
  59.             override fun isLongPressDragEnabled(): Boolean {
  60.                 //禁用默认拖动
  61.                 return false
  62.             }
  63.             override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {}
  64.         })
  65.         //赋予RecycleView滑动能力
  66.         itemTouchHelper.attachToRecyclerView(rv_table)
  67.         TableAdapter().let {
  68.             it.mTableList = tableList
  69.             rv_table.adapter = it
  70.             //将拖动职能传递给Adapter
  71.             it.mItemTouchHelper = itemTouchHelper
  72.         }
  73.     }
  1. class TableAdapter : RecyclerView.Adapter<TableAdapter.TableViewHolder>(){
  2.     var mTableList = ArrayList<String>()
  3.     var mItemTouchHelper: ItemTouchHelper? = null
  4.  
  5.     override fun getItemCount(): Int {
  6.         return mTableList.size
  7.     }
  8.  
  9.     override fun onBindViewHolder(holder: TableViewHolder, position: Int) {
  10.         val table = mTableList[position]
  11.         holder.tvTabe.text = table
  12.     }
  13.  
  14.     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TableViewHolder {
  15.         val view = LayoutInflater.from(parent.context).inflate(R.layout.item_table, parent, false)
  16.         return TableViewHolder(view)
  17.     }
  18.  
  19.     inner class TableViewHolder constructor(view: View): RecyclerView.ViewHolder(view) {
  20.         val tvTabe = view.findViewById<TextView>(R.id.tv_table)
  21.         var toPosition = -1
  22.  
  23.         init {
  24.             tvTabe.setOnLongClickListener {
  25.                 if (this.adapterPosition != 0){
  26.                     mItemTouchHelper?.startDrag(this)
  27.                     return@setOnLongClickListener true
  28.                 }
  29.                 return@setOnLongClickListener false
  30.             }
  31.         }
  32.     }
  33. }

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