突出显示选中的路由
将选中项与返回栈同步。
突出显示选中的路由 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。
Selection Must Be Real
A tab should light up because of where the user actually is, not a value you set by hand. The back stack is your source of truth. 🧭
Read the Current Entry
Ask the NavController for the live currentBackStackEntryAsState. It updates automatically every time navigation changes.
val entry by navController.currentBackStackEntryAsState()Get the Active Route
From that entry you read the active route string off its destination. That string tells you which tab is showing.
val route = entry?.destination?.routeCompare to Mark Selected
Now set each item selected by comparing the active route to that tab route. The match becomes the highlighted selected tab.
selected = route == tab.routeHierarchy Beats Equality
For nested graphs, exact equality can miss. Checking the destination hierarchy marks a tab active even on its sub-screens.
selected = entry?.destination?.hierarchy?.any {
it.route == tab.route
} == trueNavigate on Tap
In onClick, call navController.navigate with the tab route to move there. The selection then follows the back stack on its own.
onClick = { navController.navigate(tab.route) }Avoid Stacking Copies
Tapping a tab repeatedly should not pile up screens. Use launchSingleTop so only one copy of a destination stays on top.
navController.navigate(tab.route) {
launchSingleTop = true
}Pop to the Start
Pressing back from any tab should return to your home tab, not walk every tab you visited. popUpTo the start destination fixes that.
popUpTo(navController.graph.startDestinationId) {
saveState = true
}Tint the Active Tab
NavigationBarItem auto-tints the selected item, but you can theme it with colors so the active tab matches your brand.
colors = NavigationBarItemDefaults.colors(
selectedIconColor = MaterialTheme.colorScheme.primary
)Label Visibility
Use alwaysShowLabel to decide if unselected tabs still show text. Showing only the active label is a common clean look.
alwaysShowLabel = falseOne Reactive Loop
Put it together: read the route once, then in your forEach compare each tab to it. Selection now mirrors navigation perfectly.
Quick Check
You wired selection to the back stack. One quick question.
Recap
You synced highlighting to the back stack: read the current route, compare per tab, navigate with launchSingleTop and popUpTo. Selection now stays honest. 🎯
常见问题解答
「突出显示选中的路由」课时是免费的吗？
是的 — 「突出显示选中的路由」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。
「突出显示选中的路由」这节课中我会学到什么？
将选中项与返回栈同步。 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。
「突出显示选中的路由」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。