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Composable 目标页面与路由

将每个屏幕注册为一条路由。

Composable 目标页面与路由 是 CoddyKit 上的免费 Jetpack Compose Academy 课时。这是第 2 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。

Screens as Destinations

Every screen in your graph is a destination. You register one with the composable builder inside the NavHost, naming it with a route.

composable("home") { HomeScreen() }

What a Route Really Is

A route is a unique string key for a destination. Compose matches the string you navigate to against the routes you declared.

Keep Routes in Constants

Typos in raw strings cause silent failures. Store each route as a constant so the compiler catches mistakes for you.

object Routes {
    const val HOME = "home"
    const val SETTINGS = "settings"
}

A Sealed Class of Screens

For larger apps, a sealed class groups all routes in one place. It makes adding screens safe and easy to discover.

sealed class Screen(val route: String) {
    object Home : Screen("home")
    object Settings : Screen("settings")
}

Register Each Destination

List every screen with its own composable block. The lambda body is the UI shown when that route becomes active.

NavHost(navController, startDestination = Screen.Home.route) {
    composable(Screen.Home.route) { HomeScreen() }
    composable(Screen.Settings.route) { SettingsScreen() }
}

Navigate to a Route

Use the same route string to move there. The NavController finds the matching destination and the NavHost renders it.

navController.navigate(Screen.Settings.route)

Routes Must Be Unique

Two destinations cannot share a route. Each route is an address, and duplicate addresses make navigation ambiguous and unreliable.

Pass the Controller Down

Screens often trigger navigation, so hand each destination a way to navigate. A common pattern passes lambdas instead of the whole controller.

composable("home") {
    HomeScreen(onOpenSettings = { navController.navigate("settings") })
}

Keep Screens Decoupled

Passing lambdas instead of the NavController keeps screens testable and reusable. The screen says what happened, not how to navigate.

Routes Look Like URLs

Treat routes like little URLs. This style pays off later when you add arguments and deep links that open routes from outside the app.

Group Related Flows

As graphs grow, you can split screens into nested graphs with their own routes. This keeps a feature's destinations tidy and self-contained.

Quick Check

Why prefer constants or a sealed class for routes?

Recap

You learned that each screen is a destination with a unique route, and that constants or a sealed class keep those routes safe and organized. 🗂️

常见问题解答

「Composable 目标页面与路由」课时是免费的吗？

是的 — 「Composable 目标页面与路由」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。

「Composable 目标页面与路由」这节课中我会学到什么？

将每个屏幕注册为一条路由。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 2 节课，共 4 节。

「Composable 目标页面与路由」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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