androidx.navigation | Android 开发者

Kotlin |Java

Navigation is a framework for navigating between 'destinations' within an Android application that provides a consistent API whether destinations are implemented as Fragments, Activities, or other components.

There are 3 major components in Navigation.

NavGraph: A navigation graph encapsulates a set of destinations. It can be created by inflating a navigation XML file, by constructing it programmatically, or a combination of the two.
NavController: This is the main entry point for interacting with the Navigation Graph, translating calls to navigate(int), popBackStack(), and navigateUp() into the appropriate operations.
NavHost: The container that hosts a NavController and provides support for one or more specific types of destinations. For example, NavHostFragment allows you to use fragment destinations.

Below is an example of working with a NavController.

 // File: HomeFragment.java
 public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
   // For example purposes, assume our layout created in onCreateView has a Button
   // that should navigate the user to a destination
   Button b = view.findViewById(R.id.view_details);

   b.setOnClickListener(v -> {
       // Retrieve the NavController from any View within a NavHost
       NavController navController = Navigation.findNavController(v);
       navController.navigate(R.id.details));
   }

   // Or use the convenience method in Navigation to combine the previous steps
   b.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.details));
 }

Please see the documentation of individual classes for details.

Annotations

NavDestination.ClassType	This optional annotation allows tooling to offer auto-complete for the `android:name` attribute.
Navigator.Name	This annotation should be added to each Navigator subclass to denote the default name used to register the Navigator with a `NavigatorProvider`.

Interfaces

FloatingWindow	A marker interface for `NavDestination` subclasses that float above the view of other destinations (i.e.
NavArgs	An interface marking generated Args classes.
NavController.OnDestinationChangedListener	OnDestinationChangedListener receives a callback when the `NavController.getCurrentDestination()` or its arguments change.
NavDirections	An interface that describes a navigation operation: action's id and arguments
NavHost	A host is a single context or container for navigation via a `NavController`.
Navigator.Extras	Interface indicating that this class should be passed to its respective `Navigator` to enable Navigator specific behavior.

Classes

ActionOnlyNavDirections	An implementation of `NavDirections` without any arguments.
ActivityNavigator	ActivityNavigator implements cross-activity navigation.
ActivityNavigator.Destination	NavDestination for activity navigation
ActivityNavigator.Extras	Extras that can be passed to ActivityNavigator to customize what `ActivityOptionsCompat` and flags are passed through to the call to `ContextCompat.startActivity(Context, Intent, Bundle)`.
ActivityNavigator.Extras.Builder	Builder for constructing new `ActivityNavigator.Extras` instances.
NavAction	Navigation actions provide a level of indirection between your navigation code and the underlying destinations.
NavArgument	NavArgument denotes an argument that is supported by a `NavDestination`.
NavArgument.Builder	A builder for constructing `NavArgument` instances.
NavBackStackEntry	Representation of an entry in the back stack of a `NavController`.
NavController	NavController manages app navigation within a `NavHost`.
NavDeepLink	NavDeepLink encapsulates the parsing and matching of a navigation deep link.
NavDeepLink.Builder	A builder for constructing `NavDeepLink` instances.
NavDeepLinkBuilder	Class used to construct deep links to a particular destination in a `NavGraph`.
NavDeepLinkRequest	A request for a deep link in a `NavDestination`.
NavDeepLinkRequest.Builder	A builder for constructing `NavDeepLinkRequest` instances.
NavDestination	NavDestination represents one node within an overall navigation graph.
NavGraph	NavGraph is a collection of `NavDestination` nodes fetchable by ID.
NavGraphNavigator	A Navigator built specifically for `NavGraph` elements.
NavHostController	Subclass of `NavController` that offers additional APIs for use by a `NavHost` to connect the NavController to external dependencies.
Navigation	Entry point for navigation operations.
Navigator<D extends NavDestination>	Navigator defines a mechanism for navigating within an app.
NavigatorProvider	A NavigationProvider stores a set of `Navigator`s that are valid ways to navigate to a destination.
NavInflater	Class which translates a navigation XML file into a `NavGraph`
NavOptions	NavOptions stores special options for navigate actions
NavOptions.Builder	Builder for constructing new instances of NavOptions.
NavType<T>	NavType denotes the type that can be used in a `NavArgument`.
NavType.EnumType<D extends Enum>	EnumType is used for `NavArgument`s holding enum values.
NavType.ParcelableArrayType<D extends Parcelable>	ParcelableArrayType is used for `NavArgument`s which hold arrays of Parcelables.
NavType.ParcelableType<D>	ParcelableType is used for passing Parcelables in `NavArgument`s.
NavType.SerializableArrayType<D extends Serializable>	SerializableArrayType is used for `NavArgument`s that hold arrays of Serializables.
NavType.SerializableType<D extends Serializable>	SerializableType is used for Serializable `NavArgument`s.