我有一个RecyclerView
的布局是一个GridLayout
的3列。我正在使用itemtouchhelper拖放GridLayout
的RecyclerView
。在适配器中,有一个方法onItemMove()
通知我已移动的项。它只交换我拖放的ArrayList
中的那些项。但由于拖拽,其他元素也发生了变化。我想更新他们在ArrayList
中的位置。
这是我的RecyclerView的适配器:
public class GridAdapter extends RecyclerView.Adapter<GridAdapter.MyViewHolder> implements com.sagar.quizdemo.helper.ItemTouchHelperAdapter {
String[] str = {"Level 1", "Level 2", "Level 3", "Level 4", "Level 5", "Level 6", "Level 7", "Level 8", "Level 9"};
List<String> itemList, actualList;
LayoutInflater inflater;
Context context;
private final OnStartDragListener mDragStartListener;
public GridAdapter(Context context, OnStartDragListener dragStartListener) {
this.context = context;
mDragStartListener = dragStartListener;
inflater = LayoutInflater.from(context);
itemList = new ArrayList<>();
actualList = new ArrayList<>(Arrays.asList(str));
}
public void getItemList(List<String> nameList) {
int currentSize = itemList.size();
itemList.clear();
itemList.addAll(nameList);
notifyItemRangeRemoved(0, currentSize);
notifyItemRangeInserted(0, nameList.size());
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.custom_level_row, parent, false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(final MyViewHolder holder, int position) {
holder.textView.setText(itemList.get(position));
// Start a drag whenever the handle view it touched
holder.cardView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_DOWN) {
mDragStartListener.onStartDrag(holder);
}
return false;
}
});
}
@Override
public int getItemCount() {
return itemList.size();
}
@Override
public boolean onItemMove(int fromPosition, int toPosition) {
Collections.swap(itemList, fromPosition, toPosition);
notifyItemMoved(fromPosition, toPosition);
notifyItemChanged(fromPosition);
notifyItemChanged(toPosition);
return true;
}
@Override
public void onItemDismiss(int position) {
itemList.remove(position);
notifyItemRemoved(position);
}
public class MyViewHolder extends RecyclerView.ViewHolder implements ItemTouchHelperViewHolder {
CardView cardView;
TextView textView;
public MyViewHolder(View itemView) {
super(itemView);
cardView = (CardView) itemView.findViewById(R.id.gameCard);
textView = (TextView) itemView.findViewById(R.id.gameText);
}
@Override
public void onItemSelected() {
itemView.setBackgroundColor(Color.LTGRAY);
}
@Override
public void onItemClear() {
itemView.setBackgroundColor(Color.WHITE);
}
}
}
如果最初的列表是:
{"Level 1", "Level 2", "Level 3", "Level 4", "Level 5", "Level 6", "Level 7", "Level 8", "Level 9"}
在我交换了RecyclerView中的第2和第4个定位元素之后。更新后的列表应如下所示(我希望如此):
{"Level 1", "Level 5", "Level 2", "Level 3", "Level 4", "Level 6", "Level 7", "Level 8", "Level 9"}
但我得到了最新的名单:
{"Level 1", "Level 5", "Level 3", "Level 4", "Level 2", "Level 6", "Level 7", "Level 8", "Level 9"}
最佳答案
我认为你的问题是你使用Collections.swap(itemList, fromPosition, toPosition);
,它交换指定位置上的对象。所以输出是正确的。但你需要的是:
String item = itemList.remove(fromPostion);
itemList.insert(item, toPosition);