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

Question

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?

Answer 1

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

Put below code in onCreate() method of Activity.

Kotlin code

val navHostFragment = (supportFragmentManager.findFragmentById(R.id.home_nav_fragment) as NavHostFragment) val inflater = navHostFragment.navController.navInflater val graph = inflater.inflate(R.navigation.nav_main) //graph.addArgument("argument", NavArgument) 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.addArgument("argument", NavArgument) 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()); 

Additional Info

As @artnest suggested, remove the app:navGraph attribute from the layout. It would look something like this after removal

<?xml version="1.0" encoding="utf-8"?> <FrameLayout 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">      <androidx.fragment.app.FragmentContainerView         android:id="@+id/home_nav_fragment"         android:name="androidx.navigation.fragment.NavHostFragment"         android:layout_width="match_parent"         android:layout_height="match_parent"         app:defaultNavHost="true" />  </FrameLayout> 

In the case of a fragment tag used instead of FragmentContainerView, the above changes remain the same

Answer 2

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>