Agfdhyk

I am using Navigation from Android Jetpack to navigate between screens.
Now I want to set startDestination dynamically.

I have an Activity named MainActivity
And two Fragments, FragmentA & FragmentB.

var isAllSetUp : Boolean = // It is dynamic and I’m getting this from Preferences.



    If(isAllSetUp)

    {

     // show FragmentA

    }

    else

    {

     //show FragmentB

    }

I want to set above flow using Navigation Architecture Component. Currently I have used startDestionation as below but it’s not fulfilling my requirement.

<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/lrf_navigation"

   app:startDestination="@id/fragmentA">



   <fragment

       android:id="@+id/fragmentA"

       android:name="com.mindinventory.FragmentA"

       android:label="fragment_a"

       tools:layout="@layout/fragment_a" />

</navigation>

Is it possible to set startDestination conditionally using Android Navigation Architecture Component?

Finally, I got a solution to my query...

Put below code in onCreate() method of Activity.

Kotlin code

val navHostFragment = home_nav_fragment as NavHostFragment

val inflater = navHostFragment.navController.navInflater

val graph = inflater.inflate(R.navigation.nav_main)

graph.setDefaultArguments(intent.extras)

graph.startDestination = R.id.fragment1

//or

//graph.startDestination = R.id.fragment2



navHostFragment.navController.graph = graph

Java code

NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.home_nav_fragment);  // Hostfragment

NavInflater inflater = navHostFragment.getNavController().getNavInflater();

NavGraph graph = inflater.inflate(R.navigation.nav_main);

graph.setDefaultArguments(getIntent().getExtras());

graph.setStartDestination(R.id.fragment1);



navHostFragment.getNavController().setGraph(graph);

navHostFragment.getNavController().getGraph().setDefaultArguments(getIntent().getExtras());





NavigationView navigationView = findViewById(R.id.navigationView);

NavigationUI.setupWithNavController(navigationView, navHostFragment.getNavController());

Some of the APIs have changed, are unavailable or are not necessary since Akash's answer. It's a bit simpler now.

MainActivity.java:

@Override

protected void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  setContentView(R.layout.activity_main);



  NavHostFragment navHost = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_main_nav_host);

  NavController navController = navHost.getNavController();



  NavInflater navInflater = navController.getNavInflater();

  NavGraph graph = navInflater.inflate(R.navigation.navigation_main);



  if (false) {

    graph.setStartDestination(R.id.oneFragment);

  } else {

    graph.setStartDestination(R.id.twoFragment);

  }



  navController.setGraph(graph);

}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<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=".MainActivity">



  <!-- Following line omitted inside <fragment> -->

  <!-- app:navGraph="@navigation/navigation_main" -->

  <fragment

    android:id="@+id/fragment_main_nav_host"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:name="androidx.navigation.fragment.NavHostFragment"

  />



</androidx.constraintlayout.widget.ConstraintLayout>

navigation_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<!-- Following line omitted inside <navigation>-->

<!-- app:startDestination="@id/oneFragment" -->

<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_main"

  >



  <fragment

    android:id="@+id/oneFragment"

    android:name="com.apponymous.apponymous.OneFragment"

    android:label="fragment_one"

    tools:layout="@layout/fragment_one"/>

  <fragment

    android:id="@+id/twoFragment"

    android:name="com.apponymous.apponymous.TwoFragment"

    android:label="fragment_two"

    tools:layout="@layout/fragment_two"/>

</navigation>

This can be done with navigation action. Because fragmentA is your start destination, so define an action in fragmentA.

Note these two fields:
app:popUpToInclusive="true" app:popUpTo="@id/fragmentA"

<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/lrf_navigation"

   app:startDestination="@id/fragmentA">



   <fragment

       android:id="@+id/fragmentA"

       android:name="com.mindinventory.FragmentA"

       android:label="fragment_a"

       tools:layout="@layout/fragment_a">



    <action android:id="@+id/action_a_to_b"

            app:destination="@id/fragmentB"

            app:popUpToInclusive="true"

            app:popUpTo="@id/fragmentA"/>

   <fragment>



   <fragment

       android:id="@+id/fragmentB"

       android:name="com.mindinventory.FragmentB"

       android:label="fragment_b"

       tools:layout="@layout/fragment_b"/>

</navigation>

When your MainActivity started, just do the navigation with action id, it will remove fragmentA in the stack, and jump to fragmentB. Seemingly, fragmentB is your start destination.

if(!isAllSetUp)

{

  // FragmentB

  navController.navigate(R.id.action_a_to_b)

}