Dagger-Hilt依赖注入失效：repository未初始化问题解决

问题背景 #

使用Dagger-Hilt版本2.48，相关代码及报错如下：

AppModule类 #

@Module
@InstallIn(SingletonComponent::class)
object AppModule {

@Provides
@Singleton
fun provideDatabase(@ApplicationContext context: Context) =
    Room.databaseBuilder(context, V2BasketDatabase::class.java, "basket_database")
        .fallbackToDestructiveMigration()
        .allowMainThreadQueries()
        .build()

@Provides
@Singleton
fun provideContext(@ApplicationContext appContext: Context): Context {
    return appContext
}

@Provides
@Singleton
fun provideBasketDao(db: V2BasketDatabase) = db.basketDao()
}

ViewModel代码 #

@HiltViewModel
class V2CoffeeShopMenuFragmentViewModel @Inject constructor(application: Application) 
: BaseViewModel(application) {

private lateinit var readAllData: LiveData<List<V2ModelBasket>>

@Inject
lateinit var repository: V2BasketRepository

fun initDb(context: Context) {
    readAllData = repository.readAllData
}

fun readProductByProductId(productId: Int): V2ModelBasket? {
    return if (repository.readProductByProductId(productId) != null)
        repository.readProductByProductId(productId)
    else null
}
}

Fragment中ViewModel使用方式 #

private val viewModel: V2CoffeeShopMenuFragmentViewModel by viewModels()

报错信息 #

kotlin.UninitializedPropertyAccessException: lateinit property repository has not been initialized

修复方案 #

1. 配置Repository的注入绑定 #

Hilt无法自动初始化V2BasketRepository，核心原因是缺少该类的注入绑定，二选一即可：

• 方案A：给Repository添加@Inject构造函数
  让Hilt自动识别并创建实例：

class V2BasketRepository @Inject constructor(
    private val basketDao: V2BasketDao
) {
    val readAllData: LiveData<List<V2ModelBasket>> = basketDao.getAllItems()
    
    fun readProductByProductId(productId: Int): V2ModelBasket? {
        return basketDao.getProductById(productId)
    }
}

• 方案B：在AppModule中添加provides方法
  手动提供Repository实例：

@Module
@InstallIn(SingletonComponent::class)
object AppModule {
    // ... 原有代码 ...
    @Provides
    @Singleton
    fun provideBasketRepository(basketDao: V2BasketDao): V2BasketRepository {
        return V2BasketRepository(basketDao)
    }
}

2. 修正ViewModel的注入逻辑 #

ViewModel中不要用@Inject lateinit var延迟注入，直接在构造函数中注入Repository，确保ViewModel创建时依赖已初始化：

@HiltViewModel
class V2CoffeeShopMenuFragmentViewModel @Inject constructor(
    application: Application,
    private val repository: V2BasketRepository // 构造函数直接注入
) : BaseViewModel(application) {

private lateinit var readAllData: LiveData<List<V2ModelBasket>>

init {
    // 直接初始化数据，无需手动传Context
    readAllData = repository.readAllData
}

fun readProductByProductId(productId: Int): V2ModelBasket? {
    return repository.readProductByProductId(productId)
}
}

3. 补全Hilt全局配置 #

• Application类添加@HiltAndroidApp注解
  这是Hilt的入口配置：

@HiltAndroidApp
class MyApplication : Application() {
    // 自定义逻辑
}

• Fragment添加@AndroidEntryPoint注解
  确保Fragment能获取Hilt的依赖注入能力：

@AndroidEntryPoint
class V2CoffeeShopMenuFragment : Fragment() {
    private val viewModel: V2CoffeeShopMenuFragmentViewModel by viewModels()
    
    // 业务逻辑
}

4. 移除冗余的initDb方法 #

数据库、Dao、Repository的依赖链已通过Hilt自动关联，无需手动传递Context，直接删除initDb方法即可。

内容的提问来源于stack exchange，提问作者Pooya Jannati Poor