Android ViewModel 的 Hilt 范围限于 Navgraph，Provider Factory 问题

Question

我正在使用 Hilt 进行 依赖注入 ，专门用于注入 ViewModel。还想将 ViewModel 范围扩展到 NavGraph。为此，通过传递 NavGraph 获得 ViewModelStoreOwner，现在通过传递 [=] 创建 ViewModel 29=]将 navgraph 提供的实例存储到 ViewModelProvider。我面临的问题是，因为我只传递 store 实例 来获取 ViewModelProvider 而没有任何 Factory，因为 Hilt 将实现它，我收到构建错误 没有零参数构造函数 。当看到源代码时，我发现因为我只提供 store instance 作为参数而没有工厂，自动提供了一个简单的工厂由于 提供的工厂没有参数，因此出现此错误。

如何解决？

正在从源调用的方法 (ViewModelProvider.java)-

     * Creates {@code ViewModelProvider}. This will create {@code ViewModels}
     * and retain them in a store of the given {@code ViewModelStoreOwner}.
     * <p>
     * This method will use the
     * {@link HasDefaultViewModelProviderFactory#getDefaultViewModelProviderFactory() default factory}
     * if the owner implements {@link HasDefaultViewModelProviderFactory}. Otherwise, a
     * {@link NewInstanceFactory} will be used.
     */
    public ViewModelProvider(@NonNull ViewModelStoreOwner owner) {
        this(owner.getViewModelStore(), owner instanceof HasDefaultViewModelProviderFactory
                ? ((HasDefaultViewModelProviderFactory) owner).getDefaultViewModelProviderFactory()
                : NewInstanceFactory.getInstance());
    }

我的 ViewModel Class 需要依赖注入-

    private Repository repository;
    private MutableLiveData<FeatureCollection> featureCollection = new MutableLiveData<>();
    private MutableLiveData<Boolean> loading = new MutableLiveData<>();
    private Disposable disposable;


    @ViewModelInject
    public QuakeListViewModel(Repository repository) {
        this.repository = repository;
    }

我的片段class-

    private FragmentQuakeListBinding _binding;
    private QuakeListViewModel _viewModel;
    private ViewModelStoreOwner viewModelStoreOwner;
    private NavController _navController;
 @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        _navController = NavHostFragment.findNavController(this);
        viewModelStoreOwner =  _navController.getViewModelStoreOwner(R.id.main_nav_graph);

    }

public View onCreateView(@NotNull LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        //other implementation
        _viewModel = new ViewModelProvider(viewModelStoreOwner).get(QuakeListViewModel.class);
        //return binding.root
    }

任何帮助将不胜感激

谢谢

Answer 1

根据 Integration with the Jetpack navigation library documentation:

If your ViewModel is scoped to the navigation graph, use the defaultViewModelProviderFactory object that is available to activities and fragments that are annotated with @AndroidEntryPoint.

所以你可以使用：

_viewModel = new ViewModelProvider(viewModelStoreOwner,
    getDefaultViewModelProviderFactory()).get(QuakeListViewModel.class);

Android ViewModel 的 Hilt 范围限于 Navgraph，Provider Factory 问题

Android Hilt with ViewModel scoped to Navgraph, Provider Factory issue

android

dependency-injection

android-jetpack

dagger-hilt