使用firebase保存物品移动的recyclerview的位置

Question

当我将项目拖动到另一个位置时，我想保存我的recyclerView项目的位置，目前我可以拖动它并将项目设置为另一个位置，但是当我切换片段时，Recycler View恢复到原来的状态位置。如何在Firebase参考上移动项目时如何保存位置？

这是我的RecyclerAdapter

public class RolesAdapter extends RecyclerView.Adapter<RolesAdapter.MyViewHolder> implements ItemTouchHelperAdapter{
private List<Roles> mRolesList;
private Context mContext;

public RolesAdapter(Context context, List<Roles> rolesList){
    this.mContext = context;
    this.mRolesList = rolesList;
}

@Override
public boolean onItemMove(int fromPosition, int toPosition) {
    Collections.swap(mRolesList, fromPosition, toPosition);
    notifyItemMoved(fromPosition, toPosition);
    return true;
}

@Override
public void onItemDismiss(int position) {
    mRolesList.remove(position);
    notifyItemRemoved(position);

}

public class MyViewHolder extends RecyclerView.ViewHolder implements ItemTouchHelperViewHolder{
    TextView nombreRol;
    LinearLayout parentLayout;



    public MyViewHolder(View itemView) {
        super(itemView);
        nombreRol = (TextView) itemView.findViewById(R.id.nombreRol);
        parentLayout = (LinearLayout) itemView.findViewById(R.id.parentLayout);
    }

    @Override
    public void onItemSelected() {
        itemView.setBackgroundColor(Color.LTGRAY);
    }

    @Override
    public void onItemClear() {
        itemView.setBackgroundColor(0);
    }
}

这是我的ItemTouchHelperCallBack

public class SimpleItemTouchCallback extends ItemTouchHelper.Callback {
public static final float ALPHA_FULL = 1.0f;

private final ItemTouchHelperAdapter mAdapter;

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

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

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

@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    // Set movement flags based on the layout manager
    if (recyclerView.getLayoutManager() instanceof GridLayoutManager) {
        final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
        final int swipeFlags = 0;
        return makeMovementFlags(dragFlags, swipeFlags);
    } else {
        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) {
    if (source.getItemViewType() != target.getItemViewType()) {
        return false;
    }

    // Notify the adapter of the move
    mAdapter.onItemMove(source.getAdapterPosition(), target.getAdapterPosition());
    return true;
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int i) {
    // Notify the adapter of the dismissal
    mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
}

@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
    if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
        // Fade out the view as it is swiped out of the parent's bounds
        final float alpha = ALPHA_FULL - Math.abs(dX) / (float) viewHolder.itemView.getWidth();
        viewHolder.itemView.setAlpha(alpha);
        viewHolder.itemView.setTranslationX(dX);
    } else {
        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
    }
}

@Override
public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
    // We only want the active item to change
    if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
        if (viewHolder instanceof ItemTouchHelperViewHolder) {
            // Let the view holder know that this item is being moved or dragged
            ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
            itemViewHolder.onItemSelected();
        }
    }

    super.onSelectedChanged(viewHolder, actionState);
}

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

    viewHolder.itemView.setAlpha(ALPHA_FULL);

    if (viewHolder instanceof ItemTouchHelperViewHolder) {
        // Tell the view holder it's time to restore the idle state
        ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
        itemViewHolder.onItemClear();
    }
}

}

感谢您的时间和耐心！