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一般任务：我想为 FirebaseRecyclerAdapter 实现“拖放”和“滑动关闭”功能。它应该像这样工作： 拖动和滑动 .gif 示例。 首先，我将创建一个允许传递事件回调的接口：

public interface ItemTouchHelperAdapter {
boolean onItemMove(int fromPosition, int toPosition);
void onItemDismiss(int position);  }

比创建 ItemTouchHelperCallback，允许监听“移动”和“滑动”事件的接口：

public class ItemTouchHelperCallback extends ItemTouchHelper.Callback  {
private final ItemTouchHelperAdapter mAdapter;
public ItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {
    mAdapter = adapter;
}

@Override
public boolean isLongPressDragEnabled() {
    return true;
}

@Override
public boolean isItemViewSwipeEnabled() {
    return true;
}
@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;
    return makeMovementFlags(dragFlags, swipeFlags);
}

@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    mAdapter.onItemMove(viewHolder.getAdapterPosition(),target.getAdapterPosition());
    return true;
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
}}

最后创建实现之前创建的 ItemTouchHelperAdapter 的 FirebaseRecyclerAdapter：

public class PurchaseListAdapter extends FirebaseRecyclerAdapter<Purchase, PurchaseListHolder> implements ItemTouchHelperAdapter {
public PurchaseListAdapter(Class<Purchase> modelClass, int modelLayout, Class<PurchaseListHolder> viewHolderClass, Query ref) {
    super(modelClass, modelLayout, viewHolderClass, ref);
}

@Override
protected void populateViewHolder(PurchaseListHolder viewHolder, final Purchase model, final int position) {
    viewHolder.mName.setText(model.getName());
}

@Override
protected void onChildChanged(ChangeEventListener.EventType type, int index, int oldIndex) {
    super.onChildChanged(type, index, oldIndex);
}

@Override
public boolean onItemMove(int fromPosition, int toPosition) {
   // TODO: Add functionality for swapping items in FirebaseDatabase
    return true;
}

@Override
public void onItemDismiss(int position) {
    getRef(position).removeValue();
}}

“滑动关闭”（onItemDismiss）的功能非常有效。但我不知道如何实现 onItemMove 功能。理想情况下，它应该在 Firebase 数据库中滑动项目，但我没有找到办法。

也许有人知道为 RecyclerView 实现“滑动解雇”和“药物和丢弃”功能的任何其他方式，这将与 Firebase 一起使用？

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