android itemtouchhelper如何实现滑动删除

要实现滑动删除功能，您需要使用ItemTouchHelper类。以下是实现滑动删除的步骤：

1. 首先，确保您的项目已经添加了RecyclerView支持库的依赖项。在app的build.gradle文件中添加以下依赖：

dependencies {
    implementation 'androidx.recyclerview:recyclerview:1.2.1'
}

2. 创建一个适配器类，继承自RecyclerView.Adapter，并实现必要的方法。在这个类中，您需要定义一个接口来处理滑动事件：

public interface OnItemSwipeListener {
    void onItemSwiped(int position);
}

3. 在适配器类中添加一个OnItemSwipeListener成员变量，并在构造函数中接收一个实例。然后，在onBindViewHolder方法中设置滑动监听器：

private OnItemSwipeListener mListener;

public MyAdapter(OnItemSwipeListener listener) {
    mListener = listener;
}

@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
    holder.itemView.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                mStartX = event.getX();
                mStartY = event.getY();
            } else if (event.getAction() == MotionEvent.ACTION_UP) {
                float endX = event.getX();
                float endY = event.getY();
                float deltaX = endX - mStartX;
                float deltaY = endY - mStartY;

                if (Math.abs(deltaX) > Math.abs(deltaY)) {
                    if (deltaX > 0) {
                        if (mListener != null) {
                            mListener.onItemSwiped(position);
                        }
                    } else {
                        // Handle left swipe
                    }
                } else {
                    if (deltaY > 0) {
                        // Handle down swipe
                    } else {
                        // Handle up swipe
                    }
                }
            }
            return false;
        }
    });
}

4. 在您的Activity或Fragment中，创建一个ItemTouchHelper.Callback子类，并重写onInterceptTouchEvent和onMove方法：

private class MyItemTouchHelperCallback extends ItemTouchHelper.Callback {

    private final MyAdapter mAdapter;

    public MyItemTouchHelperCallback(MyAdapter adapter) {
        mAdapter = adapter;
    }

    @Override
    public boolean onInterceptTouchEvent(RecyclerView recyclerView, MotionEvent e) {
        return false;
    }

    @Override
    public void onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        if (viewHolder instanceof MyViewHolder) {
            mAdapter.notifyItemRemoved(viewHolder.getAdapterPosition());
            mAdapter.notifyItemRangeChanged(viewHolder.getAdapterPosition(), mAdapter.getItemCount());
        }
    }
}

5. 在Activity或Fragment中，初始化ItemTouchHelper并附加到RecyclerView：

MyAdapter mAdapter = new MyAdapter(/* pass your data here */);
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(mAdapter);

ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new MyItemTouchHelperCallback(mAdapter));
itemTouchHelper.attachToRecyclerView(recyclerView);

现在，当用户滑动列表项时，将触发onSwiped方法，从而删除相应的列表项。您可以根据需要自定义删除动画和其他细节。