Jetpack组合+导航:从不同的BottomBar屏幕导航到BottomBar目的地

Question

问题：

BottomBar有4个目的地:ScreenA、ScreenB、ScreenC和ScreenD。

在ScreenA上按下按钮(不是下栏项)时，我想使用参数转到ScreenB。

代码：

NavGraph

AnimatedNavHost(navController = navController, startDestination = "screen_a") {
    composable("screen_a") {
        ScreenA(navToScreenB = {
            navController.navigate("screen_b?param=1") {
        })
    }
    navigation(
        route = "screen_b",
        startDestination = "screen_b?param={param}",
    ) {
        composable(
            route = "screen_b?param={param}",
            arguments = listOf(navArgument("param") { type = NavType.IntType })
        ) { backStackEntry ->
            val param =  backStackEntry.arguments?.getBoolean("param") ?: 0
            ScreenB(param = param)
        }
        composable(route = "screen_b/details") {
            ScreenB_details(...)
        }
    }
}

BottomBar

fun BottomNavigation(navController: NavController, selectedNavigation: Screen) {
    val items = listOf(...)
    BottomNavigation(
        backgroundColor = MaterialTheme.colors.primary
    ) {
        items.forEach { item -> BottomNavigationItem(
                onClick = {
                    navController.navigate(item.screen.route) {
                        navController.graph.startDestinationRoute?.let { route ->
                            popUpTo(route) { saveState = true }
                        }
                        launchSingleTop = true
                        restoreState = true
                    }
                }
            )
        }
    }
}

到目前为止，单击ScreenA上的按钮将我导航到ScreenB，但是param值始终为0，因为我永远不会传递在navToScreenB lambda中传递的arg。我使用的是compose_version =‘1.2.0-alpha 04’和compose_version

Answer 1

结果表明，路由中的{param}和navArgument({param})必须完全相同，即使路径看起来正确并且路由中有args。

Answer 2

详细说明上面@Kamil的答案，如果您是在BottomNavigationItem.onClick中这样做的

navController.navigate(item.screen.route) {
  navController.graph.startDestinationRoute?.let { route ->
    popUpTo(route) { saveState = true }
  }
  launchSingleTop = true
  restoreState = true
}

然后，您还应该在其他地方执行相同的参数，这时需要对BottomNavigationItem进行更改。

navController.graph.startDestinationRoute?.let { route ->
  popUpTo(route) { saveState = true }
}
launchSingleTop = true
restoreState = true