给recycleview添加一个拖拽更换位置

最新推荐文章于 2024-08-12 03:48:16 发布

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本文介绍如何在Android应用中实现RecyclerView的项拖拽及拖拽过程中的背景变色效果。通过ItemTouchHelper和自定义回调，实现了上下左右方向的拖拽，并在拖拽过程中改变ViewHolder的背景颜色。

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1.使用

   ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new SimpItemTouchHelper());
        itemTouchHelper.attachToRecyclerView(recycleview);

2.关于这个helper

  /*对于拖拽事件*/
    class SimpItemTouchHelper extends ItemTouchHelper.Callback{

        @Override
        public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
            if(recyclerView.getLayoutManager() instanceof LinearLayoutManager){
                //参数表示可以拖拽的方向
                return makeMovementFlags(ItemTouchHelper.UP|ItemTouchHelper.DOWN,ItemTouchHelper.END);
            }else {
                return makeMovementFlags(ItemTouchHelper.UP|ItemTouchHelper.DOWN|ItemTouchHelper.LEFT|ItemTouchHelper.RIGHT,ItemTouchHelper.END);
            }

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


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

        }
    }

3.拖动的过程变色

 @Override
        public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
            super.onSelectedChanged(viewHolder, actionState);
            if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            viewHolder.itemView.setBackgroundColor(Color.parseColor("#000000"));}
        }