How to build NavGraph programmatically with Java in Android

Question

I know it is easy to build a NavGraph with XML, but how to implement it with java code?

Fragment XML definition without "app:navGraph" attribute:

<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:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
/>

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

TestActivity.java

NavController navController = Navigation.findNavController(activity, R.id.nav_host_fragment);

// How to pass the Class argument into the getNavigator?
NavGraph navGraph = new NavGraph(navController.getNavigatorProvider().getNavigator(???));

Question: How to create a new NavGraph object here? Which navigatorClass should be used as the argument of method "getNavigator(Class)"?

androidx.navigation.NavigatorProvider.java

/**
 * Retrieves a registered {@link Navigator} using the name provided by the
 * {@link Navigator.Name Navigator.Name annotation}.
 *
 * @param navigatorClass class of the navigator to return
 * @return the registered navigator with the given {@link Navigator.Name}
 *
 * @throws IllegalArgumentException if the Navigator does not have a
 * {@link Navigator.Name Navigator.Name annotation}
 * @throws IllegalStateException if the Navigator has not been added
 *
 * @see #addNavigator(Navigator)
 */
@NonNull
public final <T extends Navigator<?>> T getNavigator(@NonNull Class<T> navigatorClass) {
    String name = getNameForNavigator(navigatorClass);
    return getNavigator(name);
}

Thanks.

Thanks @Askar, that link is inflate NavGraph with XML definition. I found this link from "developer.android.com" but it uses Kotlin to build NavGraph programmatically instead of Java. I don't understand with the Kotlin code inside. Please help to check and see how to convert it to Java. Thanks. The link: developer.android.com/guide/navigation/navigation-kotlin-dsl — stackbiz
– stackbiz, Commented May 19, 2020 at 8:29

Askar · Accepted Answer · 2020-05-19 08:50:49Z

3

Please see java code here:

NavHostFragment myNavHostFragment = (NavHostFragment) findViewById(R.id.my_nav_host_fragment);
NavInflater inflater = myNavHostFragment.getNavController().getNavInflater();
NavGraph graph = inflater.inflate(R.navigation.my_nav_graph);
myNavHostFragment.getNavController().setGraph(graph);

answered May 19, 2020 at 8:50

Askar

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1 Comment

stackbiz Over a year ago

Get it now. Thanks for your help.

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