ViewModel + LiveData in Fragment，从ItemDetailFragment返回时如何保留ListItemFragment的数据

public class MyViewModel extends ViewModel {
    private MutableLiveData<String> data;

    public LiveData<String> getData() {
        if (data == null) {
            data = new MutableLiveData<>();
        }
        return data;
    }

    public void setData(String newData) {
        data.setValue(newData);
    }
}

public class ListItemFragment extends Fragment {
    private MyViewModel viewModel;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        viewModel = new ViewModelProvider(requireActivity()).get(MyViewModel.class);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // 布局和视图初始化
        // ...

        // 观察数据的变化
        viewModel.getData().observe(getViewLifecycleOwner(), new Observer<String>() {
            @Override
            public void onChanged(String newData) {
                // 更新UI显示
                // ...
            }
        });

        return view;
    }
}

public class ItemDetailFragment extends Fragment {
    private MyViewModel viewModel;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        viewModel = new ViewModelProvider(requireActivity()).get(MyViewModel.class);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // 布局和视图初始化
        // ...

        // 更新数据
        String newData = "新的数据";
        viewModel.setData(newData);

        // 返回到ListItemFragment
        requireActivity().onBackPressed();

        return view;
    }
}