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hiltViewModel 与 @HiltViewModel

将 ViewModel 注入 Composable。

hiltViewModel 与 @HiltViewModel 是 CoddyKit 上的免费 Jetpack Compose Academy 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Jetpack Compose Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Jetpack Compose Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

ViewModels Need Dependencies Too

Your ViewModel usually depends on a repository or use case. Hilt can inject those for you, so you never build them by hand again.

Annotate the ViewModel

Mark the class with @HiltViewModel and add @Inject to its constructor. Hilt now knows how to create it with all its dependencies.

@HiltViewModel
class FeedViewModel @Inject constructor(private val repo: Repo) : ViewModel()

Inject Anything It Needs

Constructor parameters can be any type Hilt knows, like a repository, a use case, or a logger. Hilt resolves the whole chain for you.

@HiltViewModel
class FeedViewModel @Inject constructor(
    repo: Repo, logger: Logger
) : ViewModel()

Get One in Compose

Inside a Composable, call hiltViewModel() to obtain a Hilt-built ViewModel. No factory boilerplate, just one clean call.

@Composable
fun FeedScreen(vm: FeedViewModel = hiltViewModel()) { }

Add the Compose Dependency

hiltViewModel() lives in the hilt-navigation-compose artifact. Add it to your Gradle file so the function is available in your screens.

implementation("androidx.hilt:hilt-navigation-compose:1.2.0")

Default Parameter Pattern

Putting hiltViewModel() as a default parameter keeps the Composable testable. A test can still pass a fake ViewModel directly.

@Composable
fun FeedScreen(vm: FeedViewModel = hiltViewModel())

Scoped to the Owner

hiltViewModel() scopes the instance to the nearest ViewModelStoreOwner, usually the Activity or nav destination, so it survives recomposition.

One ViewModel Per Destination

Inside a NavHost, each destination gets its own ViewModel instance. Navigate away and back, and that screen receives a fresh one.

Mark the Activity Too

The host Activity must carry @AndroidEntryPoint so Hilt can deliver ViewModels into its Composables. Without it, injection fails.

@AndroidEntryPoint
class MainActivity : ComponentActivity()

Expose State, Hide Logic

The injected ViewModel exposes UI state and the screen just reads it. Your Composable stays thin while logic lives in one tested place.

val state by vm.uiState.collectAsStateWithLifecycle()

No Manual Factories

Before Hilt you wrote a ViewModelProvider.Factory for each ViewModel with arguments. Hilt removes that boilerplate completely. 🎁

Quick Check

Which pair correctly sets up a Hilt-injected ViewModel for a Composable?

Recap: Injected ViewModels

You learned to tag a ViewModel with @HiltViewModel and fetch it via hiltViewModel(), scoped to its owner with zero factory code. ✨

常见问题解答

「hiltViewModel 与 @HiltViewModel」课时是免费的吗？

是的 — 「hiltViewModel 与 @HiltViewModel」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Jetpack Compose Academy 课程的其余内容，请升级到 CoddyKit PRO。 Jetpack Compose Academy 课程共包含 4 节课。

「hiltViewModel 与 @HiltViewModel」这节课中我会学到什么？

将 ViewModel 注入 Composable。你通过在浏览器中直接运行的动手代码来练习 Jetpack Compose Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Jetpack Compose Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Jetpack Compose Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「hiltViewModel 与 @HiltViewModel」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Jetpack Compose Academy 课中编写并运行代码吗？

能。每节 Jetpack Compose Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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