Android recyclerview实现拖拽排序和侧滑删除

Recyclerview现在基本已经替代Listview了，RecyclerView也越来越好用了 当我们有实现条目的拖拽排序和侧滑删除时 可以直接时候Recyclerview提供的API就可以直接实现了先贴上主要代码

private void initveiw() {  ArrayList<String> items = new ArrayList<>(Arrays.asList("itme1", "item2", "itme3", "item4", "item5", "item6", "item7", "item8", "itme9", "item10", "itme11", "item12", "item13", "item14", "item15", "item16"));  recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));  SimpleAdapter adapter = new SimpleAdapter(items);  recyclerView.setAdapter(adapter);  ItemTouchHelper helper = new ItemTouchHelper(new MyItemTouchCallback(adapter));  helper.attachToRecyclerView(recyclerView);}public class MyItemTouchCallback extends ItemTouchHelper.Callback{  private SimpleAdapter adapter;  public MyItemTouchCallback(SimpleAdapter adapter) {    this.adapter = adapter;  }  @Override  public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {    int dragFlag;    int swipeFlag;    RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();    if (manager instanceof GridLayoutManager){      dragFlag = ItemTouchHelper.DOWN | ItemTouchHelper.UP | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;      swipeFlag = 0;    }else{      dragFlag = ItemTouchHelper.DOWN | ItemTouchHelper.UP;      swipeFlag = ItemTouchHelper.END | ItemTouchHelper.START;    }    return makeMovementFlags(dragFlag,swipeFlag);  }  @Override  public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {    int fromPosition = viewHolder.getAdapterPosition();    int toPosition = target.getAdapterPosition();    if (fromPosition < toPosition ){      for (int i = fromPosition ;i<toPosition ;i++){        Collections.swap(adapter.getDataList(),i,i+1);      }    }else{      for (int i= fromPosition; i>toPosition; i--){        Collections.swap(adapter.getDataList(),i ,i-1);      }    }    recyclerView.getAdapter().notifyItemMoved(fromPosition,toPosition);    return true;  }  @Override  public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {    int position = viewHolder.getAdapterPosition();    if (direction == ItemTouchHelper.END | direction==ItemTouchHelper.START){      adapter.getDataList().remove(position);      adapter.notifyItemRemoved(position);    }  }  @Override  public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {    super.onSelectedChanged(viewHolder, actionState);    if (actionState==ItemTouchHelper.ACTION_STATE_DRAG){      viewHolder.itemView.setBackgroundColor(Color.BLUE);    }  }  @Override  public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {    super.clearView(recyclerView, viewHolder);    viewHolder.itemView.setBackgroundColor(0);  }}

步骤：

创建 ItemTouchHelper 对象时候，需要我们传入一个实现了 ItemTouchHelper.Callback 接口的对象。而排序和删除的逻辑都封装在了这个 ItemTouchHelper.Callback 的对象里面了。

private void initveiw() {  ArrayList<String> items = new ArrayList<>(Arrays.asList("itme1", "item2", "itme3", "item4", "item5", "item6", "item7", "item8", "itme9", "item10", "itme11", "item12", "item13", "item14", "item15", "item16"));  recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));  SimpleAdapter adapter = new SimpleAdapter(items);  recyclerView.setAdapter(adapter);  ItemTouchHelper helper = new ItemTouchHelper(new MyItemTouchCallback(adapter));  helper.attachToRecyclerView(recyclerView);}

实现ItemTouchHelper.Callback 接口后有三个方法需要重写：

getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) ：设置滑动类型的标记。需要设置两种类型的 flag ，即 dragFlags 和 swipeFlags ，分别代表着拖拽标记和滑动标记。最后需要调用 makeMovementFlags(dragFlags,swipeFlags)方法来合成返回。onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) ：当用户拖拽列表某个 item 时会回调。很明显，拖拽排序的代码应该在这个方法中实现。

onSwiped(RecyclerView.ViewHolder viewHolder, int direction) ：当用户滑动列表某个 item 时会回调。所以侧滑删除的代码应该在这个方法中实现。下面是重写的几个方法：

第一个，getMovementFlags方法

@Overridepublic int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {  int dragFlag;  int swipeFlag;  RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();  if (manager instanceof GridLayoutManager){    dragFlag = ItemTouchHelper.DOWN | ItemTouchHelper.UP | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;    swipeFlag = 0;  }else{    dragFlag = ItemTouchHelper.DOWN | ItemTouchHelper.UP;    swipeFlag = ItemTouchHelper.END | ItemTouchHelper.START;  }  return makeMovementFlags(dragFlag,swipeFlag);}

这个方法里面根据LayoutManager分了两种情况，根据自己的情况去分在GridLayoutManager中只能上下左右拖拽但是不能侧滑删除，所以swipFlag = 0；swipeFlag的值ItemTouchHelper.END是右滑删除，ItemTouchHelper.START是左滑删除最后调用makeMovementFlags方法合成返回

第二个，onMove方法

@Overridepublic boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {  int fromPosition = viewHolder.getAdapterPosition();  int toPosition = target.getAdapterPosition();  if (fromPosition < toPosition ){    for (int i = fromPosition ;i<toPosition ;i++){      Collections.swap(adapter.getDataList(),i,i+1);    }  }else{    for (int i= fromPosition; i>toPosition; i--){      Collections.swap(adapter.getDataList(),i ,i-1);    }  }  recyclerView.getAdapter().notifyItemMoved(fromPosition,toPosition);  return true;}

这个方法是用户在拖拽 item 的时候调用。所以关于列表排序的代码应该写在这里。方法参数中的 viewHolder 代表的是用户当前拖拽的 item ，而 target 代表的是被用户拖拽所覆盖的那个 item 。所以在 onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) 方法中的逻辑就是把 fromPosition 至 toPosition 为止改变它们的位置。

第三个，onSwiped方法

@Overridepublic void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {  int position = viewHolder.getAdapterPosition();  if (direction == ItemTouchHelper.END | direction==ItemTouchHelper.START){    adapter.getDataList().remove(position);    adapter.notifyItemRemoved(position);  }}

这个方法是在用户侧滑的时候调用的 ，在里面对adapter的数据进行删除就可以了

最后两个方法

 @Override  public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {    super.onSelectedChanged(viewHolder, actionState);    if (actionState==ItemTouchHelper.ACTION_STATE_DRAG){      viewHolder.itemView.setBackgroundColor(Color.BLUE);    }  }  @Override  public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {    super.clearView(recyclerView, viewHolder);    viewHolder.itemView.setBackgroundColor(0);  }}

就是优化的方法，第一个是选择条目改变状态，第二个是手指抬起之后恢复条目状态

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。

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