RecyclerView实现侧滑删除+拖拽移动

完成类似于下图的效果:
1.侧滑删除
2.拖拽移动

一.写一个接口,TouchCallBack

public interface TouchCallBack {
    //数据交换
    void onItemMove(int fromPosition, int toPosition);

    //数据删除
    void onItemDelete(int position);
}

二.RecyclerView的适配器实现这个接口

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> implements TouchCallBack {
    private Context context;
    private ArrayList<String> list;

    public MyAdapter(Context context, ArrayList<String> list) {
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(context).inflate(R.layout.layout_item, null);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder viewHolder, int i) {
        String str = list.get(i);
        viewHolder.tv.setText(str);
    }

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

    @Override
    public void onItemMove(int fromPosition, int toPosition) {
        //交换位置
        Collections.swap(list, fromPosition, toPosition);
        //局部刷新(移动)
        notifyItemMoved(fromPosition, toPosition);
    }

    @Override
    public void onItemDelete(int position) {
        //删除数据
        list.remove(position);
        //局部刷新(移除)
        notifyItemRemoved(position);
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        private TextView tv;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            tv = itemView.findViewById(R.id.tv);
        }
    }
}

三.需要用到一个类,ItemTouchCallBack ,它是RecyclerView.ItemDecoration的子类.

这是一个工具类，可实现滑动删除和拖拽移动，使用这个工具类需要RecyclerView和Callback，它配置了启用了何种类型的交互，并且当用户执行这些操作时也会接收事件。
这个类中有如下方法可以实现侧滑删除和拖拽移动功能:

public class SimpleItemTouchCallBack extends ItemTouchHelper.Callback {

    private TouchCallBack mCallBack;
    //左滑删除的
    private boolean mSwipeEnable = true;

    public SimpleItemTouchCallBack(TouchCallBack mCallBack) {
        this.mCallBack = mCallBack;
    }

    /**
     * 返回可以滑动的方向,一般使用makeMovementFlags(int,int)
     * 或makeFlag(int, int)来构造我们的返回值
     *
     * @param recyclerView
     * @param viewHolder
     * @return
     */
    @Override
    public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {

        //允许上下拖拽
        int drag = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
        //允许向左滑动
        int swipe = ItemTouchHelper.LEFT;
        //设置
        return makeMovementFlags(drag, swipe);
    }

    /**
     * 上下拖动item时回调,可以调用Adapter的notifyItemMoved方法来交换两个ViewHolder的位置，
     * 最后返回true，
     * 表示被拖动的ViewHolder已经移动到了目的位置
     *
     * @param recyclerView
     * @param viewHolder
     * @param target
     * @return
     */
    @Override
    public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
        //通知适配器,两个子条目位置发生改变
        mCallBack.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
        return true;
    }

    /**
     * 当用户左右滑动item时达到删除条件就会调用,一般为一半,条目继续滑动删除,否则弹回
     *
     * @param viewHolder
     * @param direction
     */
    @Override
    public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
        mCallBack.onItemDelete(viewHolder.getAdapterPosition());
    }

    /**
     * 支持长按拖动,默认是true
     *
     * @return
     */
    @Override
    public boolean isLongPressDragEnabled() {
        return super.isLongPressDragEnabled();
    }

    /**
     * 支持滑动,即可以调用到onSwiped()方法,默认是true
     *
     * @return
     */
    @Override
    public boolean isItemViewSwipeEnabled() {
        return mSwipeEnable;
    }

    /**
     * 设置是否支持左滑删除
     *
     * @param enable
     */
    public void setmSwipeEnable(boolean enable) {
        this.mSwipeEnable = enable;
    }
}

四、在MainActivity中

public class MainActivity extends AppCompatActivity {

    private RecyclerView lv;

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

    private void initView() {
        lv = (RecyclerView) findViewById(R.id.lv);
        ArrayList<String> list = new ArrayList<>();
        for (int i = 0; i < 8; i++) {
            list.add("安琪拉"+i);
        }
        MyAdapter adapter = new MyAdapter(this, list);
        lv.setAdapter(adapter);
        lv.setLayoutManager(new LinearLayoutManager(this));

        // 拖拽移动和左滑删除
        SimpleItemTouchCallBack simpleItemTouchCallBack = new SimpleItemTouchCallBack(adapter);
        // 要实现侧滑删除条目，把 false 改成 true 就可以了
        simpleItemTouchCallBack.setmSwipeEnable(false);
        ItemTouchHelper helper = new ItemTouchHelper(simpleItemTouchCallBack);
        helper.attachToRecyclerView(lv);
    }
}