Why my app seems not responding after adding fragment in my mainActivity when implementing Navigation Graph?

Question

I am trying to learn how to use the navigation controller. and the problem is, My app seems not responding, it takes a very long time to show the main activity, and I can't also press the back button (seems not active)

here is the screenshot of my navigation graph, I am trying to set the host fragment in my Main Activity, as you can see, it seems a little bit weird that the bottom navigation view and the toolbar seem double on the NavHostFragment.

here is the screenshot of my main activity:

here is my mainActivity xml:

<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <android.support.v7.widget.Toolbar
            android:layout_width="0dp"

            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            android:theme="?attr/actionBarTheme"
            android:minHeight="?attr/actionBarSize"
            android:id="@+id/toolbar"
            app:layout_constraintTop_toTopOf="parent" app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"/>


    <fragment
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:id="@+id/nav_host_fragment"
            app:layout_constraintBottom_toTopOf="@+id/bottom_nav"
            app:layout_constraintTop_toBottomOf="@+id/toolbar"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            android:name="androidx.navigation.fragment.NavHostFragment"
            app:navGraph="@navigation/navigation_graph"
            app:defaultNavHost="true"
    />


    <android.support.design.widget.BottomNavigationView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:background="@color/colorPrimary"
            app:itemIconTint="@color/color_bottom_view_navigation"
            app:itemTextColor="@color/color_bottom_view_navigation"
            app:menu="@menu/menu_bottom_view"
            app:labelVisibilityMode="labeled"
            android:id="@+id/bottom_nav"/>




</android.support.constraint.ConstraintLayout>

and here is the xml of navigation graph:

<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" 
            android:id="@+id/navigation_graph"
            app:startDestination="@id/mainActivity">


    <activity android:id="@+id/mainActivity" android:name="com.muchammadagunglaksana.navcontroller.MainActivity"
              android:label="activity_main" tools:layout="@layout/activity_main"/>
</navigation>

and here is my MainActivity class:

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val navController = Navigation.findNavController(this, R.id.nav_host_fragment)

        setupBottomNavMenu(navController)
        setupActionBar(navController)
    }

    private fun setupBottomNavMenu(navController: NavController) {
        bottom_nav?.let {
            NavigationUI.setupWithNavController(it, navController)
        }
    }


    private fun setupActionBar(navController: NavController) {
        NavigationUI.setupActionBarWithNavController(this, navController)
    }


    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.menu_toolbar, menu)
        return true
    }
}

what went wrong in here?

Answer 1

It is because you are adding the same activity(mainActivity) as your start destination inside nav host fragment that is also part of main activity.

Solution is you have to remove main activty as your starting destination and add anotehr fragment/activity in it. 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" 
        android:id="@+id/navigation_graph"
        app:startDestination="@id/mainFragment">


 <fragment android:id="@+id/mainFragment"
          android:name="com.cinderellaman.general.ui.fragments.MainFragment"
          android:label="main_fragment"
          tools:layout="@layout/main_fragment"/></navigation>