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Navigator

public abstract class Navigator
extends Object

java.lang.Object
   ↳ androidx.navigation.Navigator<D extends androidx.navigation.NavDestination>

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

interface Navigator.Extras

Interface indicating that this class should be passed to its respective Navigator to enable Navigator specific behavior. 

@interface Navigator.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

Navigator()

Public methods

abstract D createDestination()

Construct a new NavDestination associated with this Navigator.

abstract NavDestination navigate(D destination, Bundle args, NavOptions navOptions, Navigator.Extras navigatorExtras)

Navigate to a destination.

void onRestoreState(Bundle savedState)

Restore any state previously saved in onSaveState().

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.

Inherited methods

Public constructors

public Navigator ()

Public methods

createDestination

public abstract D createDestination ()

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.

Returns
D a new NavDestination 

public abstract NavDestination navigate (D destination, 
                Bundle args, 
                NavOptions navOptions, 
                Navigator.Extras navigatorExtras)

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.
Returns
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

public void onRestoreState (Bundle savedState)

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

public Bundle onSaveState ()

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

Returns
Bundle

popBackStack

public abstract boolean popBackStack ()

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.

Returns
boolean true if pop was successful