约束布局中片段的视图绑定不起作用

Question

我有以下代码:

activity_reminders.xml

<androidx.constraintlayout.widget.ConstraintLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".locationreminders.RemindersActivity">
<fragment
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/nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>

ReminderActivity.kt

class RemindersActivity : AppCompatActivity() {
private lateinit var binding: ActivityRemindersBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityRemindersBinding.inflate(layoutInflater)
setContentView(binding.root)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when (item.itemId) {
android.R.id.home -> {
(binding.navHostFragment as NavHostFragment).navController.popBackStack()
return true
}
}
return super.onOptionsItemSelected(item)
}

}

绑定。navHostFragment在未解决的，我不明白为什么，如果我改变视图的类型在任何不同，然后"碎片"视图绑定工作了。是否可以使用视图绑定在另一个视图内的片段?

Answer 1

我找到了以下作为获得片段的变通解决方案。

val navHostFragment = findNavController(R.id.nav_host_fragment)
navHostFragment.popBackStack()

我认为这是不可能使用因为fragment不是View的后代。

Answer 2

而不是:

(binding.navHostFragment as NavHostFragment).navController.popBackStack()

使用以下代码:

(supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment).navController.popBackStack()