I am using the Android Navigation Architecture Components for navigating a Fragment-based-, Single-Activity-application. The main navigation is implemented via NavigationDrawer-pattern: DrawerLayout with NavigationView and NavHostFragment plus and additional Toolbar.
Everything is working fine so far - I am able to navigate to every Fragment -, except for the BackStack of the main-level Fragments. Any Fragment other than the startDestination seems to be added to the BackStack instead of being replaced like a regular NavigationDrawer would do.
The misbehavior can be identified via the Burger-icon that switches to a Back-icon as soon as I navigate to a Fragment other than the startDestination, and by navigating back which leads me to the startDestination instead of exiting the app.
How should the Navigation Architecture Components be used in order to replace the main Fragments in combination with a NavigationView?
I am initializing the Navigation Architecture Components like this:
class MainActivity : AppCompatActivity {
private val navigationHostFragment: NavHostFragment
get() = supportFragmentManager.findFragmentById(R.id.navigationHost) as NavHostFragment
private val navigationController: NavController
get() = navigationHostFragment.navController
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity)
// Views are bound via Kotlin Android Extensions
setSupportActionBar(toolbar)
NavigationUI.setupWithNavController(toolbar, navigationController, drawerLayout)
NavigationUI.setupWithNavController(navigationView, navigationController)
}
override fun onSupportNavigateUp(): Boolean = findNavController(R.id.navigationHost).navigateUp()
}
The layout for the activity (/res/layout/activity.xml) looks like this:
<androidx.drawerlayout.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawerLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"/>
<fragment
android:id="@+id/navigationHost"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:navGraph="@navigation/navigation"
app:defaultNavHost="true"/>
</LinearLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/navigationView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:menu="@menu/navigation"/>
</androidx.drawerlayout.widget.DrawerLayout>
The navigation graph (/res/navigation/navigation.xml) looks like this:
<navigation
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"
app:startDestination="@id/first">
<fragment
android:id="@+id/first"
android:name="de.example.FirstFragment"
android:label="@string/first"/>
<fragment
android:id="@+id/second"
android:name="de.example.SecondFragment"
android:label="@string/second"/>
</navigation>
The menu for the NavigationView (/res/menu/navigation.xml) looks like this:
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group android:checkableBehavior="single">
<item
android:id="@+id/first"
android:title="@string/first"/>
<item
android:id="@+id/second"
android:title="@string/second"/>
</group>
</menu>
The relevant dependencies look like this:
dependencies {
implementation 'com.google.android.material:material:1.0.0'
implementation 'androidx.core:core-ktx:1.0.0'
implementation 'android.arch.navigation:navigation-fragment-ktx:1.0.0-alpha06'
implementation 'android.arch.navigation:navigation-ui-ktx:1.0.0-alpha06'
}
