使用findNavController的FragmentContainerView

问题描述

我将Android导航组件与底部导航一起使用，棉绒给出了有关将<fragment>标记替换为FragmentContainerView的警告，但是当我替换时，findNavController无法正常工作时，它给我有关它没有错误的错误NavController设置为

I'm using Android Navigation Component with bottom navigation, lint gives a warning about replacing the <fragment> tag with FragmentContainerView but when i replaced, findNavController is not working it gives me error about it does not have a NavController set on

片段

<androidx.fragment.app.FragmentContainerView
            android:id="@+id/nav_host_fragment"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="true"
            app:navGraph="@navigation/mobile_navigation" />

活动

val navController = findNavController(R.id.nav_host_fragment)

    val appBarConfiguration = AppBarConfiguration(
        setOf(
            R.id.navigation_classes, R.id.navigation_schedule, R.id.navigation_settings
        )
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
    navView.setupWithNavController(navController)
}

推荐答案

根据此问题 ，当使用FragmentContainerView时，您需要使用findFragmentById()查找NavController，而不是在onCreate()中使用findNavController():

As per this issue, when using FragmentContainerView, you need to find the NavController using findFragmentById() rather than using findNavController() when in onCreate():

val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
val navController = navHostFragment.navController

这是因为findNavController(R.id.nav_host_fragment)依赖于已经创建的片段视图，而使用FragmentContainerView则不是这种情况(因为它在引擎盖下使用FragmentTransaction来添加NavHostFragment).

This is because findNavController(R.id.nav_host_fragment) relies on the Fragment's View to already be created which isn't the case when using FragmentContainerView (as it uses a FragmentTransaction under the hood to add the NavHostFragment).

这篇关于使用findNavController的FragmentContainerView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！