Navigator

Kotlin |Java

abstract class Navigator<D : NavDestination!>

kotlin.Any
↳	androidx.navigation.Navigator

Known Direct Subclasses ActivityNavigator, ComposeNavigator, DialogFragmentNavigator, DynamicIncludeGraphNavigator, FragmentNavigator, NavGraphNavigator ActivityNavigator ActivityNavigator implements cross-activity navigation. ComposeNavigator Navigator that navigates through Composables. DialogFragmentNavigator Navigator that uses DialogFragment#show(FragmentManager, String). DynamicIncludeGraphNavigator Navigator for include-dynamic. FragmentNavigator Navigator that navigates through fragment transactions. NavGraphNavigator A Navigator built specifically for NavGraph elements.

Known Indirect Subclasses DynamicActivityNavigator, DynamicFragmentNavigator, DynamicGraphNavigator DynamicActivityNavigator Dynamic feature navigator for Activity destinations. DynamicFragmentNavigator The Navigator that enables navigating to destinations within dynamic feature modules. DynamicGraphNavigator Navigator for graphs in dynamic feature modules.

Navigator defines a mechanism for navigating within an app.

Each Navigator sets the policy for a specific type of navigation, e.g. ActivityNavigator knows how to launch into destinations backed by activities using startActivity.

Navigators should be able to manage their own back stack when navigating between two destinations that belong to that navigator. The NavController manages a back stack of navigators representing the current navigation stack across all navigators.

Each Navigator should add the Navigator.Name annotation to their class. Any custom attributes used by the associated destination subclass should have a name corresponding with the name of the Navigator, e.g., ActivityNavigator uses <declare-styleable name="ActivityNavigator">

Summary

Nested classes
abstract	Extras Interface indicating that this class should be passed to its respective Navigator to enable Navigator specific behavior.
	Name This annotation should be added to each Navigator subclass to denote the default name used to register the Navigator with a NavigatorProvider.

Public constructors
<init>() Navigator defines a mechanism for navigating within an app.

Public methods
abstract D	createDestination() Construct a new NavDestination associated with this Navigator.
abstract NavDestination?	navigate(@NonNull destination: D, @Nullable args: Bundle?, @Nullable navOptions: NavOptions?, @Nullable navigatorExtras: Navigator.Extras?) Navigate to a destination.
open Unit	onRestoreState(@NonNull savedState: Bundle) Restore any state previously saved in onSaveState().
open Bundle?	onSaveState() Called to ask for a Bundle representing the Navigator's state.
abstract Boolean	popBackStack() Attempt to pop this navigator's back stack, performing the appropriate navigation.

Public constructors

<init>

Navigator()

Navigator defines a mechanism for navigating within an app.

Each Navigator sets the policy for a specific type of navigation, e.g. ActivityNavigator knows how to launch into destinations backed by activities using startActivity.

Navigators should be able to manage their own back stack when navigating between two destinations that belong to that navigator. The NavController manages a back stack of navigators representing the current navigation stack across all navigators.

Each Navigator should add the Navigator.Name annotation to their class. Any custom attributes used by the associated destination subclass should have a name corresponding with the name of the Navigator, e.g., ActivityNavigator uses <declare-styleable name="ActivityNavigator">

Public methods

createDestination

@NonNull abstract fun createDestination(): D

Construct a new NavDestination associated with this Navigator.

Any initialization of the destination should be done in the destination's constructor as it is not guaranteed that every destination will be created through this method.

Return
D	a new NavDestination

navigate

@Nullable abstract fun navigate(
    @NonNull destination: D, 
    @Nullable args: Bundle?, 
    @Nullable navOptions: NavOptions?, 
    @Nullable navigatorExtras: Navigator.Extras?
): NavDestination?

Navigate to a destination.

Requests navigation to a given destination associated with this navigator in the navigation graph. This method generally should not be called directly; NavController will delegate to it when appropriate.

Parameters
destination	D: destination node to navigate to
args	Bundle?: arguments to use for navigation
navOptions	NavOptions?: additional options for navigation
navigatorExtras	Navigator.Extras?: extras unique to your Navigator.

Return
NavDestination?	The NavDestination that should be added to the back stack or null if no change was made to the back stack (i.e., in cases of single top operations where the destination is already on top of the back stack).

onRestoreState

open fun onRestoreState(@NonNull savedState: Bundle): Unit

Restore any state previously saved in onSaveState(). This will be called before any calls to navigate(NavDestination, Bundle, NavOptions, Navigator.Extras) or popBackStack().

Calls to createDestination() should not be dependent on any state restored here as createDestination() can be called before the state is restored.

Parameters
savedState	Bundle: The state previously saved

onSaveState

@Nullable open fun onSaveState(): Bundle?

Called to ask for a Bundle representing the Navigator's state. This will be restored in onRestoreState(Bundle).

popBackStack

abstract fun popBackStack(): Boolean

Attempt to pop this navigator's back stack, performing the appropriate navigation.

Implementations should return true if navigation was successful. Implementations should return false if navigation could not be performed, for example if the navigator's back stack was empty.

Return
Boolean	true if pop was successful