Question

我有一个RecyclerView并且已经实现了一个名为onMove的{{1}}命令。我正在使用onItemMove尝试让列表元素在拖动时交换位置，但列表元素只是悬停在每个元素上，它们不会交换。我怎么能纠正这个？

注1：onItemMove工作正常;它将项目滑开并将其从列表中删除。

注意2：我尝试onItemDismiss Override，但实际上并未覆盖其超类。

列表适配器类：这包含onItemMove命令

onItemMove

ItemTouchHelper类：

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ListViewHolder> {
    private static final String TAG = "ListAdapter";
    Context context;
    private List<UserData> dataList = new ArrayList<>();
    LayoutInflater inflater;
    Listener listener;
    DbHelper dbHelper;



    public interface Listener {
        void nameToChnge(String name);
    }

    public ListAdapter(Context context, List<UserData> dataList1) {
        this.context = context;
        this.dataList = dataList1;
        this.listener= (Listener) context;
        inflater = LayoutInflater.from(context);
    }


    @Override
    public ListViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View convertView = inflater.inflate(R.layout.recylerview_one, parent, false);
        ListViewHolder viewHolder = new ListViewHolder(convertView);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ListViewHolder holder, final int position) {
        holder.tv_name.setText(dataList.get(position).name);
        holder.tv_quantity.setText(dataList.get(position).quantity);
        holder.tv_description.setText(dataList.get(position).description + "");

        holder.relLayout.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                String s = dataList.get(position).id;
                Integer stringo = Integer.parseInt(s);
                Intent intent = new Intent(context, ItemEditActivity.class);
                intent.putExtra("ItemNumber", stringo);
                context.startActivity(intent);
            }
        });
    }

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

    class ListViewHolder extends RecyclerView.ViewHolder {
        TextView tv_name, tv_quantity, tv_description;
        RelativeLayout relLayout;


        public ListViewHolder(View itemView) {
            super(itemView);
            tv_name = (TextView) itemView.findViewById(R.id.nameDisplay);
            tv_quantity = (TextView) itemView.findViewById(R.id.quantityDisplay);
            tv_description = (TextView) itemView.findViewById(R.id.descriptionDisplay);
            relLayout = (RelativeLayout) itemView.findViewById(R.id.relLayout);
        }
    }



    public void onItemDismiss(final int position) {
        dataList.remove(position);
        notifyItemRemoved(position);

    }

    public void onItemMove(int fromPosition, int toPosition) {
        Collections.swap(dataList, fromPosition, toPosition);
        notifyItemMoved(fromPosition, toPosition);

    }
}

主要活动的一部分，我初始化public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback{ private final ListAdapter mAdapter; public SimpleItemTouchHelperCallback(ListAdapter adapter) { mAdapter = adapter; } @Ov erride 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()); } }和。{ SimpleItemTouchHelperCallback：

RecyclerView

Answer 1

您只需要研究此示例的代码并实现它：https://github.com/iPaulPro/Android-ItemTouchHelper-Demo/tree/master/app/src/main/java/co/paulburke/android/itemtouchhelperdemo

但基本上你需要的是创建两个接口。第一个：

public interface ItemTouchHelperAdapter {
/**
 * Called when an item has been dragged far enough to trigger a move. This is called every time
 * an item is shifted, and not at the end of a "drop" event.
 *
 * @param fromPosition The start position of the moved item.
 * @param toPosition   Then end position of the moved item.

 */
void onItemMove(int fromPosition, int toPosition);


/**
 * Called when an item has been dismissed by a swipe.
 *
 * @param position The position of the item dismissed.

 */
void onItemDismiss(int position);
}

第二个：

public interface ItemTouchHelperViewHolder {
    /**
      * Implementations should update the item view to indicate it's active state.
     */
    void onItemSelected();


    /**
     * state should be cleared.
     */
    void onItemClear();
}

SimpleItemTouchHelperCallback中的那样：

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {

    private final ItemTouchHelperAdapter mAdapter;

    public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {
        mAdapter = adapter;
    }

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

    @Override
    public boolean isItemViewSwipeEnabled() {
        return false;
    }

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

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

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

    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
            itemViewHolder.onItemSelected();
        }

        super.onSelectedChanged(viewHolder, actionState);
    }

    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);

        ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
        itemViewHolder.onItemClear();
    }
}

然后你必须改变RecyclerViewAdapter，并在那里实现我们在oder评论中所说的onItemMove方法。你也应该像onStartDragListener那样实现：

    public interface OnStartDragListener {
    /**
     * Called when a view is requesting a start of a drag.
     *
     * @param viewHolder The holder of the view to drag.
     */
    void onStartDrag(RecyclerView.ViewHolder viewHolder);
}

然后在你的适配器onBindViewHolder中使用它（记得在类声明中实现所有接口），就像这样（你需要根据你的变量名更改这段代码）：

holder.handleView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_DOWN) {
                    mDragStartListener.onStartDrag(holder);
                }
                return false;
            }
        });

mDragListener是OnStartDragListener变量。

最后查看本指南了解更多信息：http://valokafor.com/remember-drag-and-drop-position-with-recyclerview/

Answer 2

我找到了一个高级图书馆

https://github.com/h6ah4i/android-advancedrecyclerview?utm_source=android-arsenal.com&utm_medium=referral&utm_campaign=1432

该演示位于youtube here

为什么列表元素不能交换？

2 个答案: