Android recyclerview實現拖拽排序和側滑刪除

發布時間：2020-09-04 23:08:18 來源：腳本之家閱讀：200 作者：天安門前掃地僧欄目：移動開發

Recyclerview現在基本已經替代Listview了，RecyclerView也越來越好用了當我們有實現條目的拖拽排序和側滑刪除時可以直接時候Recyclerview提供的API就可以直接實現了
先貼上主要代碼

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);
  }
}

步驟：

創建 ItemTouchHelper 對象時候，需要我們傳入一個實現了 ItemTouchHelper.Callback 接口的對象。而排序和刪除的邏輯都封裝在了這個 ItemTouchHelper.Callback 的對象里面了。

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);
}

實現ItemTouchHelper.Callback 接口后有三個方法需要重寫：

getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) ：設置滑動類型的標記。需要設置兩種類型的 flag ，即 dragFlags 和 swipeFlags ，分別代表著拖拽標記和滑動標記。最后需要調用 makeMovementFlags(dragFlags,
swipeFlags)方法來合成返回。
onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) ：當用戶拖拽列表某個 item 時會回調。很明顯，拖拽排序的代碼應該在這個方法中實現。

onSwiped(RecyclerView.ViewHolder viewHolder, int direction) ：當用戶滑動列表某個 item 時會回調。所以側滑刪除的代碼應該在這個方法中實現。
下面是重寫的幾個方法：

第一個，getMovementFlags方法

@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);
}

這個方法里面根據LayoutManager分了兩種情況，根據自己的情況去分
在GridLayoutManager中只能上下左右拖拽但是不能側滑刪除，所以swipFlag = 0；swipeFlag的值ItemTouchHelper.END是右滑刪除，ItemTouchHelper.START是左滑刪除
最后調用makeMovementFlags方法合成返回

第二個，onMove方法

@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;
}

這個方法是用戶在拖拽 item 的時候調用。所以關于列表排序的代碼應該寫在這里。方法參數中的 viewHolder 代表的是用戶當前拖拽的 item ，而 target 代表的是被用戶拖拽所覆蓋的那個 item 。所以在 onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) 方法中的邏輯就是把 fromPosition 至 toPosition 為止改變它們的位置。

第三個，onSwiped方法

@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);
  }
}

這個方法是在用戶側滑的時候調用的，在里面對adapter的數據進行刪除就可以了

最后兩個方法

 @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);
  }
}

就是優化的方法，第一個是選擇條目改變狀態，第二個是手指抬起之后恢復條目狀態

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持億速云。

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Android recyclerview實現拖拽排序和側滑刪除

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Android recyclerview實現拖拽排序和側滑刪除

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