RecyclerView拖拽排序item工具类

package com.baselib.utils;
import com.baselib.base.adapter.BaseRVAdapter;
import java.util.List;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.RecyclerView;

public class RVItemTouchHelper<T> extends ItemTouchHelper.Callback {

    private List<T> data;
    private BaseRVAdapter adapter;
    private boolean enabled=false;

    public RVItemTouchHelper(List<T> data, BaseRVAdapter commonFunctionsAdapter) {
        this.data = data;
        this.adapter = commonFunctionsAdapter;
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
        return makeMovementFlags(dragFlags, 0);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        int fromPosition = viewHolder.getAdapterPosition();
        int toPosition = target.getAdapterPosition();
        if (fromPosition < data.size() && toPosition < data.size()) {
            T item = data.get(fromPosition);
            data.remove(fromPosition);
            data.add(toPosition, item);
            adapter.notifyItemMoved(fromPosition, toPosition);
        }
        return true;
    }
    /**
     * Item是否可以被滑动(H：左右滑动，V：上下滑动)
     * isItemViewSwipeEnabled()返回值是否可以拖拽排序，true可以，false不可以
     * @return                      true
     */
    @Override
    public boolean isItemViewSwipeEnabled() {
        //return super.isItemViewSwipeEnabled();
        return enabled;
    }
    /**
     * 当Item被长按的时候是否可以被拖拽
     *
     * @return                      true
     */
    @Override
    public boolean isLongPressDragEnabled() {
        //return super.isLongPressDragEnabled();
        return enabled;
    }

    public void setItemSwipeEnabled(boolean enabled){
        this.enabled=enabled;
    }


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

    }

    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        super.onSelectedChanged(viewHolder, actionState);
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            viewHolder.itemView.setScaleX(1f);
            viewHolder.itemView.setScaleY(1f);
        }
    }

    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);
        viewHolder.itemView.setScaleX(1.0f);
        viewHolder.itemView.setScaleY(1.0f);
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if (newState ==RecyclerView.SCROLL_STATE_IDLE){
                    //暂停
                    adapter.notifyDataSetChanged();//recyclerView滑动中不能调用此方法，所以得监听滑动
                    if (listener!=null){
                        listener.moveListener(data);
                    }
                }
            }
        });


    }

    private OnItemMoveListener listener;
    public void setOnItemMoveListener(OnItemMoveListener listener){
        this.listener=listener;
    }
    public interface OnItemMoveListener{
       <T> void moveListener(T param);
    }

}

使用

        RVItemTouchHelper cardHelperCallBack= new RVItemTouchHelper(topics, listAdapter);
        ItemTouchHelper itemTouchHelper = new ItemTouchHelper(cardHelperCallBack);
        itemTouchHelper.attachToRecyclerView(rvTopicList);
        cardHelperCallBack.setItemSwipeEnabled(true);
        cardHelperCallBack.setOnItemMoveListener(new RVItemTouchHelper.OnItemMoveListener() {
            @Override
            public <T> void moveListener(T param) {//保存按钮显示
                if (tvSaveSort.getVisibility()==View.GONE){
                    tvSaveSort.setVisibility(View.VISIBLE);
                }
                listAdapter.notifyItemAdapters();
            }
        });