onDrag 调用每个 RecyclerView.ViewHolder

Question

我的 onDrag 方法似乎被 RecyclerView 中存在的每个 RecyclerView.ViewHolder 调用。有谁知道如何防止这种情况并确保只调用一次？

ViewHolder

public class ViewHolder extends RecyclerView.ViewHolder implements OnLongClickListener, OnDragListener {
    public ImageView imgProduct;
    public TextView lblName;

    public ViewHolder(View view) {
        super(view);
        imgProduct = (ImageView)view.findViewById(R.id.imgShelfProduct);
        imgProduct.setOnLongClickListener(this);
        imgProduct.setOnDragListener(this);
        lblName = (TextView) view.findViewById(R.id.lblShelfText);
    }

    @Override
    public boolean onLongClick(View view) {
        ClipData data = ClipData.newPlainText("product", view.toString());
        DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
        view.startDrag(data, shadowBuilder, view, 0);
        return false;
    }

    @Override
    public boolean onDrag(View view, DragEvent event) {
        switch (event.getAction()) {
        case DragEvent.ACTION_DRAG_STARTED:
            Log.d(ShoppingApplication.TAG, "Started");
            return true;
        case DragEvent.ACTION_DRAG_ENTERED:
            Log.d(ShoppingApplication.TAG, "Entered");
            return true;
        case DragEvent.ACTION_DRAG_EXITED:
            Log.d(ShoppingApplication.TAG, "Exited");
            return true;
        case DragEvent.ACTION_DRAG_ENDED:
            Log.d(ShoppingApplication.TAG, "Ended");
            return true;
        default:
            break;
        }
        return false;
    }
}

onCreateViewHolder

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

onBindViewHolder

@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {
    Product product = products.get(position);
    viewHolder.lblName.setText(product.getName());
    String url = app.getImagePath();
    Picasso.with(activity).load(url).into(viewHolder.imgProduct);
}

Answer 1

我一定是误解了OnDragListener的概念。它不应该添加到可拖动视图中，而是添加到您希望将它们拖动到的视图中。所以我将它移出 RecyclerView.Adapter class 并移入 Activity class 并添加到我的目标视图中。

现在每个触发器只调用一次 onDrag 方法。

onDrag 调用每个 RecyclerView.ViewHolder

onDrag called for each RecyclerView.ViewHolder

android

drag

android-recyclerview