用java写一个recyclerView类似相册支持多选删除的例子

好的，以下是一个用 Java 编写的 RecyclerView 类似相册支持多选删除的例子：

1. 创建 RecyclerView 布局文件 `activity_main.xml`，包含一个 RecyclerView 和一个 FloatingActionButton：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="56dp" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@android:drawable/ic_menu_delete"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_margin="16dp"
        android:visibility="gone" />

</RelativeLayout>

2. 创建 RecyclerView 的 Item 布局文件 `item_photo.xml`，包含一个 ImageView 和一个 CheckBox：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:scaleType="centerCrop" />

    <CheckBox
        android:id="@+id/check_box"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentTop="true"
        android:layout_margin="8dp" />

</RelativeLayout>

3. 创建 RecyclerView 的 ViewHolder 类 `PhotoViewHolder.java`：

public class PhotoViewHolder extends RecyclerView.ViewHolder {

    public ImageView imageView;
    public CheckBox checkBox;

    public PhotoViewHolder(View itemView) {
        super(itemView);
        imageView = itemView.findViewById(R.id.image_view);
        checkBox = itemView.findViewById(R.id.check_box);
    }

}

4. 创建 RecyclerView 的 Adapter 类 `PhotoAdapter.java`：

public class PhotoAdapter extends RecyclerView.Adapter<PhotoViewHolder> {

    private List<Photo> photoList;
    private List<Photo> selectedPhotoList;
    private Context context;

    public PhotoAdapter(List<Photo> photoList, Context context) {
        this.photoList = photoList;
        this.context = context;
        selectedPhotoList = new ArrayList<>();
    }

    @Override
    public PhotoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_photo, parent, false);
        return new PhotoViewHolder(view);
    }

    @Override
    public void onBindViewHolder(PhotoViewHolder holder, int position) {
        Photo photo = photoList.get(position);
        Glide.with(context).load(photo.getUrl()).into(holder.imageView);
        holder.checkBox.setChecked(selectedPhotoList.contains(photo));
        holder.itemView.setOnClickListener(v -> {
            if (selectedPhotoList.contains(photo)) {
                selectedPhotoList.remove(photo);
            } else {
                selectedPhotoList.add(photo);
            }
            notifyDataSetChanged();
        });
    }

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

    public void deleteSelectedPhotos() {
        for (Photo photo : selectedPhotoList) {
            photoList.remove(photo);
        }
        notifyDataSetChanged();
    }

    public void showDeleteButton(boolean show) {
        ((MainActivity) context).runOnUiThread(() -> {
            FloatingActionButton fabDelete = ((MainActivity) context).findViewById(R.id.fab_delete);
            if (show) {
                fabDelete.setVisibility(View.VISIBLE);
                fabDelete.setOnClickListener(v -> {
                    deleteSelectedPhotos();
                    selectedPhotoList.clear();
                    fabDelete.setVisibility(View.GONE);
                });
            } else {
                fabDelete.setVisibility(View.GONE);
            }
        });
    }
}

5. 在 Activity 中初始化 RecyclerView 和 Adapter：

public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private PhotoAdapter photoAdapter;

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

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setLayoutManager(new GridLayoutManager(this, 3));
        List<Photo> photoList = new ArrayList<>();
        photoList.add(new Photo("https://picsum.photos/id/0/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/1/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/2/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/3/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/4/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/5/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/6/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/7/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/8/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/9/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/10/200/300"));
        photoList.add(new Photo("https://picsum.photos/id/11/200/300"));
        photoAdapter = new PhotoAdapter(photoList, this);
        recyclerView.setAdapter(photoAdapter);

        recyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
            GestureDetector gestureDetector = new GestureDetector(MainActivity.this, new GestureDetector.SimpleOnGestureListener() {
                @Override
                public boolean onSingleTapConfirmed(MotionEvent e) {
                    return true;
                }

                @Override
                public void onLongPress(MotionEvent e) {
                    View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                    if (child != null) {
                        int position = recyclerView.getChildAdapterPosition(child);
                        photoAdapter.showDeleteButton(true);
                        super.onLongPress(e);
                    }
                }
            });

            @Override
            public boolean onInterceptTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
                View child = rv.findChildViewUnder(e.getX(), e.getY());
                if (child != null && gestureDetector.onTouchEvent(e)) {
                    int position = rv.getChildAdapterPosition(child);
                    return true;
                }
                return false;
            }

            @Override
            public void onTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {

            }

            @Override
            public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {

            }
        });
    }
}

其中，`Photo` 类是一个简单的 Java 类，表示一张照片，包含一个 `url` 属性。在 `PhotoAdapter` 中，通过 Glide 加载图片，点击 Item 时选中或取消选中，长按 Item 时显示删除按钮，点击删除按钮时删除选中的照片。在 Activity 中，通过 `GestureDetector` 监听 RecyclerView 的长按事件，当长按 Item 时显示删除按钮。