RecyclerView长按拖动效果，用ItemTouchHelper实现

RecyclerView长按拖动效果，用ItemTouchHelper实现

话不多说，直接上代码

//NewItemTouchHelper继承自ItemTouchHelper.Callback
NewItemTouchHelper helper = new NewItemTouchHelper(context, adapter, info);

ItemTouchHelper itemTouchHelper = new ItemTouchHelper(helper);
//依赖在RecyclerView上
itemTouchHelper.attachToRecyclerView(rv);

---

public class NewItemTouchHelper extends android.support.v7.widget.helper.ItemTouchHelper.Callback {
    private CommonBaseAdapter adapter;
    private List<UserMenusInfo> results;
    private BaseActivity mActivity;
    private final Vibrator mVibrator;
    private final UserMenusDbUtil menusDbUtil;

    public NewItemTouchHelper(BaseActivity activity, CommonBaseAdapter adapter, List<UserMenusInfo> list) {
        super();
        this.adapter = adapter;
        this.results = list;
        this.mActivity = activity;
        mVibrator = (Vibrator) mActivity.getSystemService(Context.VIBRATOR_SERVICE);//震动
        menusDbUtil = UserMenusDbUtil.getInstance();
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        int dragFlags;//GridLayoutManager可拖动的方向分为上 下 左 右 LinearLayoutManager可拖动的方向分为上 下
        int swipFlags;
        if (recyclerView.getLayoutManager() instanceof GridLayoutManager) {
            dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
            swipFlags = 0;
        } else {
            dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
            swipFlags = 0;
        }
        return makeMovementFlags(dragFlags, swipFlags);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        int fromPosition = viewHolder.getAdapterPosition();//得到拖动ViewHolder的position
        int toPosition = target.getAdapterPosition();//得到目标ViewHolder的position
        if (fromPosition < toPosition) {
            for (int i = fromPosition; i < toPosition; i++) {
                Collections.swap(results, i, i + 1);
            }
        } else {
            for (int i = fromPosition; i > toPosition; i--) {
                Collections.swap(results, i, i - 1);
            }
        }
        adapter.notifyItemMoved(fromPosition, toPosition);
        return true;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {

    }


    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            mVibrator.vibrate(60);
            viewHolder.itemView.setBackgroundColor(Color.LTGRAY);
        }
        super.onSelectedChanged(viewHolder, actionState);
    }

    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        viewHolder.itemView.setBackgroundColor(0);

        super.clearView(recyclerView, viewHolder);
    }

}