如何实现两个RecyclerView中仅单个Checkbox可选中并联动取消？

核心思路 #

把选中状态的控制权从Adapter转移到Fragment层，让Fragment作为全局状态的协调者，统一记录当前选中的条目所属Adapter及位置。两个Adapter只负责根据Fragment传递的状态更新自身Checkbox，并在选中事件发生时通知Fragment更新全局状态，以此实现跨Adapter的单选逻辑。

具体实现步骤 #

1. 定义回调接口，实现Adapter到Fragment的事件传递 #

在Adapter中定义接口，用于将Checkbox选中事件传递给Fragment，同时用枚举区分不同Adapter：

// 区分两个Adapter的枚举
enum AdapterType {
    ADAPTER_FIRST, ADAPTER_SECOND
}

// 选中事件回调接口
public interface OnCheckboxSelectedListener {
    void onCheckboxSelected(AdapterType adapterType, int position);
}

每个Adapter在构造时传入该接口实例，用于后续事件通知：

public class FirstAdapter extends RecyclerView.Adapter<FirstAdapter.ViewHolder> {
    private OnCheckboxSelectedListener listener;
    private int internalSelectedPos = -1; // 自身内部记录的选中位置，-1表示未选中

    public FirstAdapter(OnCheckboxSelectedListener listener) {
        this.listener = listener;
    }

    // 其他Adapter基础代码省略
}

2. Fragment实现回调，管理全局选中状态 #

在Fragment中实现上述回调接口，维护全局选中的Adapter类型和位置，并在收到事件时协调两个Adapter更新状态：

public class TargetFragment extends Fragment implements OnCheckboxSelectedListener {
    private FirstAdapter firstAdapter;
    private SecondAdapter secondAdapter;
    private AdapterType currentSelectedAdapter;
    private int currentSelectedPos = -1;

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        // 初始化Adapter并传入当前Fragment作为回调
        firstAdapter = new FirstAdapter(this);
        secondAdapter = new SecondAdapter(this);
        // 给RecyclerView设置Adapter
        recyclerViewFirst.setAdapter(firstAdapter);
        recyclerViewSecond.setAdapter(secondAdapter);
    }

    @Override
    public void onCheckboxSelected(AdapterType adapterType, int position) {
        // 先清除之前选中条目的状态
        if (currentSelectedAdapter != null && currentSelectedPos != -1) {
            if (currentSelectedAdapter == AdapterType.ADAPTER_FIRST) {
                firstAdapter.clearSelection(currentSelectedPos);
            } else {
                secondAdapter.clearSelection(currentSelectedPos);
            }
        }
        // 更新全局选中状态
        currentSelectedAdapter = adapterType;
        currentSelectedPos = position;
        // 设置新选中条目的状态
        if (adapterType == AdapterType.ADAPTER_FIRST) {
            firstAdapter.setSelectedPosition(position);
        } else {
            secondAdapter.setSelectedPosition(position);
        }
    }
}

3. Adapter内部处理Checkbox状态与点击事件 #

在Adapter的onBindViewHolder中根据内部记录的选中位置设置Checkbox状态，同时给Checkbox绑定点击事件，触发回调通知Fragment：

// 以FirstAdapter为例
public class FirstAdapter extends RecyclerView.Adapter<FirstAdapter.ViewHolder> {
    private OnCheckboxSelectedListener listener;
    private int internalSelectedPos = -1;
    private List<YourDataModel> dataList;

    // 构造方法、onCreateViewHolder等基础代码省略

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        YourDataModel model = dataList.get(position);
        // 根据内部选中位置设置Checkbox状态
        holder.checkBox.setChecked(position == internalSelectedPos);

        // 绑定Checkbox选中事件
        holder.checkBox.setOnCheckedChangeListener((buttonView, isChecked) -> {
            if (isChecked) {
                listener.onCheckboxSelected(AdapterType.ADAPTER_FIRST, position);
            } else {
                // 取消选中时通知Fragment清空全局状态
                listener.onCheckboxSelected(null, -1);
            }
        });
    }

    // 设置选中位置并刷新对应条目
    public void setSelectedPosition(int position) {
        int oldPos = internalSelectedPos;
        internalSelectedPos = position;
        if (oldPos != -1) {
            notifyItemChanged(oldPos);
        }
        notifyItemChanged(position);
    }

    // 清除选中状态并刷新对应条目
    public void clearSelection(int position) {
        internalSelectedPos = -1;
        notifyItemChanged(position);
    }

    class ViewHolder extends RecyclerView.ViewHolder {
        CheckBox checkBox;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            checkBox = itemView.findViewById(R.id.item_checkbox);
        }
    }
}

4. 可选：用ViewModel实现跨Adapter状态共享（MVVM架构场景） #

如果项目使用Jetpack组件，可以用ViewModel统一管理选中状态，实现更解耦的架构：

// 定义ViewModel保存选中状态
public class SelectionViewModel extends ViewModel {
    private final MutableLiveData<Pair<AdapterType, Integer>> selectedItem = new MutableLiveData<>();

    public void updateSelectedItem(AdapterType type, int position) {
        selectedItem.setValue(new Pair<>(type, position));
    }

    public LiveData<Pair<AdapterType, Integer>> getSelectedItem() {
        return selectedItem;
    }
}

在Fragment中获取ViewModel并传递给Adapter：

public class TargetFragment extends Fragment {
    private SelectionViewModel viewModel;

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        viewModel = new ViewModelProvider(this).get(SelectionViewModel.class);
        firstAdapter = new FirstAdapter(viewModel);
        secondAdapter = new SecondAdapter(viewModel);
        // 绑定RecyclerView Adapter省略
    }
}

Adapter中观察ViewModel的状态变化，自动更新Checkbox：

public class FirstAdapter extends RecyclerView.Adapter<FirstAdapter.ViewHolder> {
    private int internalSelectedPos = -1;

    public FirstAdapter(SelectionViewModel viewModel) {
        viewModel.getSelectedItem().observeForever(pair -> {
            if (pair != null && pair.first == AdapterType.ADAPTER_FIRST) {
                internalSelectedPos = pair.second;
            } else {
                internalSelectedPos = -1;
            }
            notifyItemChanged(internalSelectedPos);
            notifyItemChanged(pair != null ? pair.second : -1);
        });
    }

    // onBindViewHolder中设置Checkbox状态，点击时更新ViewModel
    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        holder.checkBox.setChecked(position == internalSelectedPos);
        holder.checkBox.setOnCheckedChangeListener((buttonView, isChecked) -> {
            if (isChecked) {
                viewModel.updateSelectedItem(AdapterType.ADAPTER_FIRST, position);
            } else {
                viewModel.updateSelectedItem(null, -1);
            }
        });
    }
}

为什么放弃LocalBroadcast？ #

LocalBroadcastManager已被官方废弃，且基于广播的状态传递存在消息延迟、丢失的风险，相比之下Fragment直接协调或ViewModel共享状态的方式更直接可靠，代码可读性和可维护性也更高。

内容的提问来源于stack exchange，提问作者yasyes