RecyclerView拖放通過itemTouchHelper bahaving快速拖動時很奇怪

Question

我一直在關注這個鏈接的指南"Drag and Swipe with RecyclerView - by IPaulPro"，我在某些情況下幾乎沒有問題。

所以，我基本上做了所有他解釋+我加入項目一個TextView表示在RecyclerView項目的位置，這樣的事情：

一切似乎不錯，除了當我啓動「彈弓射擊「物品很快，然後我有兩個問題：

1. 它恰好有一個數字的副本。在 onItemClear()方法使用notifyAdapterSetChanged()

   而且我所做的是 - 它固定在它的方式，反而造成 IllegalStateException，其逮住 - 會導致 IndexOutOfBounds例外。

2. 偶爾，當刷卡速度太快時，項目會進入「背景」。這隻能看到，如果項目不是相同的大小。

我將粘貼下面我的整個適配器代碼，必須有一個缺陷在它的地方。

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(); 

    } 
} 

獎金問題

是否有任何教程或拖動和2個RecyclerViews之間拖放相關的任何信息？

我知道這是一個問題，但沒有答案，我可能會更幸運。

Answer 1

對我來說，似乎你的onItemMove（）沒有考慮到所有的變化。 當某物移動多於一個物品時（讓我們說在A & B之間），你正在交換兩者之間的所有物品。 但是，只能向A & B報告更改，而不會報告其他元素之間的更改。

我建議你寫報告的所有變化的交換方法：）

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); 
} 

調用此函數，而不是Collections.swap（並刪除通知代碼的其餘部分。

Answer 2

更改onitemmove方法

@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; 
} 

到：

@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); 
    return true; 
}