android - 如何在 Android recyclerView 中将多个项目拖到一起？

Question

我正在使用 simpleItemTouchHelper 在 recyclerview 中启用拖放功能。它运作良好。但我想通过拖动一个项目来拖动多个项目（特定数量-> eg.3 或 4）。在我的项目中，当我选择并拖动标题项时，我还想移动它的另一个子项。

我怎样才能做到这一点？

这是我的代码：

活动

public class TestActivity extends AppCompatActivity implements OnStartDragListener {

    RecyclerView recyclerView;
    private ItemTouchHelper mItemTouchHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        TestAdapter adapter = new TestAdapter(this,getDatas(),this);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);
        ItemTouchHelper.Callback callback = new SimpleItemTouchHelper(adapter);
        mItemTouchHelper = new ItemTouchHelper(callback);
        mItemTouchHelper.attachToRecyclerView(recyclerView);


    }

    private List<Integer> getDatas(){
        return new ArrayList<>(Arrays.asList(0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1));
    }

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

适配器：

public class TestAdapter extends RecyclerView.Adapter<TestAdapter.ItemViewHolder>
        implements ItemTouchHelperAdapter {

    private Context context;
    private List<Integer> lists;
    private OnStartDragListener onStartDragListener;

    public TestAdapter(Context context, List<Integer> lists,OnStartDragListener onStartDragListener) {
        this.context = context;
        this.lists = lists;
        this.onStartDragListener = onStartDragListener;
    }

    @Override
    public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = null;
        if(viewType == 0){
            view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_header,parent,false);
        }else if(viewType == 1){
            view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_child,parent,false);
        }
        return new ItemViewHolder(view);
    }

    @Override
    public int getItemViewType(int position) {
        return lists.get(position);
    }

    @Override
    public void onBindViewHolder(final ItemViewHolder holder, int position) {

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

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

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

    public class ItemViewHolder extends RecyclerView.ViewHolder{

        public ItemViewHolder(View itemView) {
            super(itemView);
        }
    }
}

接口在这里：

public interface OnStartDragListener {
    void onStartDrag(RecyclerView.ViewHolder viewHolder);
}


public interface ItemTouchHelperAdapter {
    boolean onItemMove(int fromPosition, int toPosition);
}