RecyclerView通过itemTouchHelper拖放,拖动时快速拖动

Question

我一直在关注这个链接的指南"使用RecyclerView拖动和滑动 - 由IPaulPro",我在某些情况下遇到的问题很少.

所以,我基本上完成了他解释的所有内容+我在项目中添加了一个TextView,表示RecyclerView中项目的位置,如下所示:

一切都很好看,除非我开始"快速射击"物品,然后我有两个问题:

1. 它碰巧有数字的重复.

   我所做的也是notifyAdapterSetChanged()在 onItemClear()方法中使用- 它以某种方式修复它,但导致了 IllegalStateException捕获 - 会导致 IndexOutOfBounds异常.

2. 有时,当刷得太快时,物品进入"背景".只有当项目大小不同时才能看到这一点.

我将在下面粘贴我的整个适配器代码,其中必须存在缺陷.

LayoutInflater inflater;
Context context;
AndroidEntityQuestionResult androidEntityQuestionResult;
ArrayList<AndroidEntityAnswer> list = new ArrayList<>();
ORDLayoutManagerQuestion ord;
ScreenDimensionsConstants sdc;


public OrderingRecycleAdapter(Context context, AndroidEntityQuestionResult androidEntityQuestionResult, ORDLayoutManagerQuestion ord) {
    inflater = LayoutInflater.from(context);
    this.context = context;
    this.list = androidEntityQuestionResult.getAndroidEntityQuestion().getEntityAnswer();
    this.androidEntityQuestionResult = androidEntityQuestionResult;
    this.ord = ord;
    sdc = new ScreenDimensionsConstants(context);
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.custom_row_ordering_rv, parent, false);
    final RecyclerView.ViewHolder holder = new OrderingViewHolder(view);
    return holder;
}


@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (holder instanceof OrderingViewHolder) {

        ((OrderingViewHolder) holder).answerText.setText(list.get(position).getAnswer().getANSWER_TEXT());
        int currentPosition = position + 1;
        ((OrderingViewHolder) holder).position.setText("#" + currentPosition);
    }
}

@Override
public int getItemCount() {
    return list.size();
}

@Override
public boolean onItemMove(int fromPosition, int toPosition) {
    if (fromPosition < toPosition) {
        for (int i = fromPosition; i < toPosition; i++) {
            Collections.swap(list, i, i + 1);
        }
    } else {
        for (int i = fromPosition; i > toPosition; i--) {
            Collections.swap(list, i, i - 1);
        }
    }
    notifyItemMoved(fromPosition, toPosition);
    notifyItemChanged(fromPosition);
    return true;
}

@Override
public void onItemDismiss(int position) {

}

@Override
public void onStartDrag(RecyclerView.ViewHolder viewHolder) {
        ord.getItemTouchHelper().startDrag(viewHolder);
}

class OrderingViewHolder extends RecyclerView.ViewHolder implements ItemTouchHelperViewHolder {
    private TextView answerText;
    private ImageView pin;
    private TextView position;

    public OrderingViewHolder(View itemView) {
        super(itemView);
        answerText = (TextView) itemView.findViewById(R.id.orderingAnswer);
        answerText.setTextSize(TypedValue.COMPLEX_UNIT_PX, sdc.getHeight() / 40);

        pin = (ImageView) itemView.findViewById(R.id.ordering_pin);
        pin.getLayoutParams().width = sdc.getHeight() / 15;
        pin.getLayoutParams().height = sdc.getHeight() / 15;

        pin.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (MotionEventCompat.getActionMasked(event) ==
                        MotionEvent.ACTION_DOWN) {
                    OrderingRecycleAdapter.this.onStartDrag(OrderingViewHolder.this);
                }
                return false;
            }
        });
        position = (TextView) itemView.findViewById(R.id.answer_position);
        position.setTextSize(TypedValue.COMPLEX_UNIT_PX, sdc.getHeight() / 40);

    }

    @Override
    public void onItemSelected() {
        itemView.setBackgroundResource(R.drawable.menu_item_background_ice_blue);
    }

    @Override
    public void onItemClear() {
        itemView.setBackgroundResource(R.drawable.menu_item_background_white);
        int currentPosition = getLayoutPosition() + 1;
        position.setText("#" + currentPosition);
       //notifyDataSetChanged();

    }
}

奖金问题

是否有任何教程或任何与2个RecyclerViews之间的拖放相关的信息？

我知道有关于SO的问题,但没有答案,我可能会更幸运.

Answer 1

对我来说，您的 onItemMove() 似乎并未考虑所有更改。当某物移动多个项目时（假设在 A 和 B 之间），您将在两者之间交换所有项目。但是，您仅报告 A 和 B 的更改，而不报告其间的其余元素。

我建议您编写一个报告所有更改的交换方法：

public boolean swapItems(int fromPosition, int toPosition){
    Collections.swap(list, fromPosition, toPosition);
    notifyItemMoved(fromPosition, toPosition);
    notifyItemMoved(toPosition, fromPosition);
    // And maybe also notifyItemChanged() as the item changes due to the shift
    notifyItemChanged(fromPosition);
    notifyItemChanged(toPosition);
}

调用此函数而不是 Collections.swap() 并删除其余的通知代码。