NavHostFragment

Artifact: androidx.navigation:navigation-fragment

Added in 1.0.0

Kotlin |Java

open class NavHostFragment : Fragment, NavHost

kotlin.Any
↳	androidx.fragment.app.Fragment
	↳	androidx.navigation.fragment.NavHostFragment

Known direct subclasses

ComposableNavHostFragment, DynamicNavHostFragment

`ComposableNavHostFragment`	A `NavHostFragment` that adds support for `ComposableFragment` instances via `ComposableFragmentNavigator`.
`DynamicNavHostFragment`	The `NavHostFragment` for dynamic features.

NavHostFragment provides an area within your layout for self-contained navigation to occur.

NavHostFragment is intended to be used as the content area within a layout resource defining your app's chrome around it, e.g.:

<androidx.drawerlayout.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.fragment.app.FragmentContainerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/my_nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        app:navGraph="@navigation/nav_sample"
        app:defaultNavHost="true" />

    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"/>;
</androidx.drawerlayout.widget.DrawerLayout>

Each NavHostFragment has a NavController that defines valid navigation within the navigation host. This includes the NavGraph as well as navigation state such as current location and back stack that will be saved and restored along with the NavHostFragment itself.

NavHostFragments register their navigation controller at the root of their view subtree such that any descendant can obtain the controller instance through the Navigation helper class's methods such as Navigation.findNavController. View event listener implementations such as android.view.View.OnClickListener within navigation destination fragments can use these helpers to navigate based on user interaction without creating a tight coupling to the navigation host.

Summary

Public companion functions
`NavHostFragment`	`create(graphResId: @NavigationRes Int, startDestinationArgs: Bundle?)` Create a new NavHostFragment instance with an inflated NavGraph resource.
`NavController`	`findNavController(fragment: Fragment)` Find a `NavController` given a local `Fragment`.

Public constructors
`NavHostFragment()`

Public functions
`open Unit`	`@CallSuper onAttach(context: Context)` Called when a fragment is first attached to its context.
`open Unit`	`@CallSuper onCreate(savedInstanceState: Bundle?)` Called to do initial creation of a fragment.
`open View?`	`onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle? )` Called to have the fragment instantiate its user interface view.
`open Unit`	`onDestroyView()` Called when the view previously created by `onCreateView` has been detached from the fragment.
`open Unit`	`@CallSuper onInflate( context: Context, attrs: AttributeSet, savedInstanceState: Bundle? )` Called when a fragment is being created as part of a view layout inflation, typically from setting the content view of an activity.
`open Unit`	`@CallSuper onSaveInstanceState(outState: Bundle)` Called to ask the fragment to save its current dynamic state, so it can later be reconstructed in a new instance if its process is restarted.
`open Unit`	`onViewCreated(view: View, savedInstanceState: Bundle?)` Called immediately after `onCreateView` has returned, but before any saved state has been restored in to the view.

Protected functions
`open Navigator<FragmentNavigator.Destination>`	`createFragmentNavigator()` This function is deprecated. Use {@link #onCreateNavController(NavController)}
`open Unit`	`@CallSuper onCreateNavController(navController: NavController)` This function is deprecated. Override {@link #onCreateNavHostController(NavHostController)} to gain access to the full {@link NavHostController} that is created by this NavHostFragment.
`open Unit`	`@CallSuper onCreateNavHostController(navHostController: NavHostController)` Callback for when the `NavHostController` is created.

Public properties
`final NavController`	`navController` The `navigation controller` for this navigation host.

Inherited functions

From androidx.fragment.app.Fragment

`open Unit`	`dump( prefix: String, fd: FileDescriptor?, writer: PrintWriter, args: Array<String>? )` Print the Fragments's state into the given stream.
`final operator Boolean`	`equals(other: Any?)` Subclasses can not override equals().
`FragmentActivity?`	`getActivity()` Return the `FragmentActivity` this fragment is currently associated with.
`open Boolean`	`getAllowEnterTransitionOverlap()` Returns whether the the exit transition and enter transition overlap or not.
`open Boolean`	`getAllowReturnTransitionOverlap()` Returns whether the the return transition and reenter transition overlap or not.
`Bundle?`	`getArguments()` Return the arguments supplied when the fragment was instantiated, if any.
`FragmentManager`	`getChildFragmentManager()` Return a private FragmentManager for placing and managing Fragments inside of this Fragment.
`open Context?`	`getContext()` Return the `Context` this fragment is currently associated with.
`open Any?`	`getEnterTransition()` Returns the Transition that will be used to move Views into the initial scene.
`open Any?`	`getExitTransition()` Returns the Transition that will be used to move Views out of the scene when the fragment is removed, hidden, or detached when not popping the back stack.
`FragmentManager?`	`getFragmentManager()` This function is deprecated. This has been removed in favor of `getParentFragmentManager()` which throws an `IllegalStateException` if the FragmentManager is null.
`Any?`	`getHost()` Return the host object of this fragment.
`Int`	`getId()` Return the identifier this fragment is known by.
`LayoutInflater`	`getLayoutInflater()` Returns the cached LayoutInflater used to inflate Views of this Fragment.
`open LoaderManager`	`getLoaderManager()` This function is deprecated. Use `LoaderManager.getInstance(this)`.
`Fragment?`	`getParentFragment()` Returns the parent Fragment containing this Fragment.
`FragmentManager`	`getParentFragmentManager()` Return the FragmentManager for interacting with fragments associated with this fragment's activity.
`open Any?`	`getReenterTransition()` Returns the Transition that will be used to move Views in to the scene when returning due to popping a back stack.
`Resources`	`getResources()` Return `requireActivity().getResources()`.
`Boolean`	`getRetainInstance()` This function is deprecated. Instead of retaining the Fragment itself, use a non-retained Fragment and keep retained state in a ViewModel attached to that Fragment.
`open Any?`	`getReturnTransition()` Returns the Transition that will be used to move Views out of the scene when the Fragment is preparing to be removed, hidden, or detached because of popping the back stack.
`open Any?`	`getSharedElementEnterTransition()` Returns the Transition that will be used for shared elements transferred into the content Scene.
`open Any?`	`getSharedElementReturnTransition()` Return the Transition that will be used for shared elements transferred back during a pop of the back stack.
`String`	`getString(resId: @StringRes Int)` Return a localized string from the application's package's default string table.
`String`	`getString(resId: @StringRes Int, vararg formatArgs: Any?)` Return a localized formatted string from the application's package's default string table, substituting the format arguments as defined in `java.util.Formatter` and format.
`String?`	`getTag()` Get the tag name of the fragment, if specified.
`Fragment?`	`getTargetFragment()` This function is deprecated. Instead of using a target fragment to pass results, use `setFragmentResult` to deliver results to `FragmentResultListener` instances registered by other fragments via `setFragmentResultListener`.
`Int`	`getTargetRequestCode()` This function is deprecated. When using the target fragment replacement of `setFragmentResultListener` and `setFragmentResult`, consider using `setArguments` to pass a `requestKey` if you need to support dynamic request keys.
`CharSequence`	`getText(resId: @StringRes Int)` Return a localized, styled CharSequence from the application's package's default string table.
`open Boolean`	`getUserVisibleHint()` This function is deprecated. Use `setMaxLifecycle` instead.
`open View?`	`getView()` Get the root view for the fragment's layout (the one returned by `onCreateView`), if provided.
`open LifecycleOwner`	`@MainThread getViewLifecycleOwner()` Get a `LifecycleOwner` that represents the `Fragment's View` lifecycle.
`open LiveData<LifecycleOwner>`	`getViewLifecycleOwnerLiveData()` Retrieve a `LiveData` which allows you to observe the `lifecycle of the Fragment's View`.
`final Int`	`hashCode()` Subclasses can not override hashCode().
`Boolean`	`isAdded()` Return true if the fragment is currently added to its activity.
`Boolean`	`isDetached()` Return true if the fragment has been explicitly detached from the UI.
`Boolean`	`isHidden()` Return true if the fragment has been hidden.
`Boolean`	`isInLayout()` Return true if the layout is included as part of an activity view hierarchy via the tag.
`Boolean`	`isRemoving()` Return true if this fragment is currently being removed from its activity.
`Boolean`	`isResumed()` Return true if the fragment is in the resumed state.
`Boolean`	`isStateSaved()` Returns true if this fragment is added and its state has already been saved by its host.
`Boolean`	`isVisible()` Return true if the fragment is currently visible to the user.
`open Unit`	`@MainThread @CallSuper onActivityCreated(savedInstanceState: Bundle?)` This function is deprecated. use `onViewCreated` for code touching the view created by `onCreateView` and `onCreate` for other initialization.
`open Unit`	`onActivityResult(requestCode: Int, resultCode: Int, data: Intent?)` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`open Unit`	`@MainThread @CallSuper onAttach(activity: Activity)` This function is deprecated. See `onAttach`.
`open Unit`	`@MainThread onAttachFragment(childFragment: Fragment)` This function is deprecated. The responsibility for listening for fragments being attached has been moved to FragmentManager.
`open Unit`	`@CallSuper onConfigurationChanged(newConfig: Configuration)`
`open Boolean`	`@MainThread onContextItemSelected(item: MenuItem)` This hook is called whenever an item in a context menu is selected.
`open Animation?`	`@MainThread onCreateAnimation(transit: Int, enter: Boolean, nextAnim: Int)` Called when a fragment loads an animation.
`open Animator?`	`@MainThread onCreateAnimator(transit: Int, enter: Boolean, nextAnim: Int)` Called when a fragment loads an animator.
`open Unit`	`@MainThread onCreateContextMenu( menu: ContextMenu, v: View, menuInfo: ContextMenu.ContextMenuInfo? )` Called when a context menu for the `view` is about to be shown.
`open Unit`	`@MainThread onCreateOptionsMenu(menu: Menu, inflater: MenuInflater)` This function is deprecated. `androidx.activity.ComponentActivity` now implements `MenuHost`, an interface that allows any component, including your activity itself, to add menu items by calling addMenuProvider without forcing all components through this single method override.
`open Unit`	`@MainThread @CallSuper onDestroy()` Called when the fragment is no longer in use.
`open Unit`	`@MainThread onDestroyOptionsMenu()` This function is deprecated. `androidx.activity.ComponentActivity` now implements `MenuHost`, an interface that allows any component, including your activity itself, to add menu items by calling addMenuProvider without forcing all components through this single method override.
`open Unit`	`@MainThread @CallSuper onDetach()` Called when the fragment is no longer attached to its activity.
`open LayoutInflater`	`onGetLayoutInflater(savedInstanceState: Bundle?)` Returns the LayoutInflater used to inflate Views of this Fragment.
`open Unit`	`@MainThread onHiddenChanged(hidden: Boolean)` Called when the hidden state (as returned by `isHidden` of the fragment or another fragment in its hierarchy has changed.
`open Unit`	`@UiThread @CallSuper onInflate( activity: Activity, attrs: AttributeSet, savedInstanceState: Bundle? )` This function is deprecated. See `onInflate`.
`open Unit`	`@MainThread @CallSuper onLowMemory()`
`open Unit`	`onMultiWindowModeChanged(isInMultiWindowMode: Boolean)` Called when the Fragment's activity changes from fullscreen mode to multi-window mode and visa-versa.
`open Boolean`	`@MainThread onOptionsItemSelected(item: MenuItem)` This function is deprecated. `androidx.activity.ComponentActivity` now implements `MenuHost`, an interface that allows any component, including your activity itself, to add menu items by calling addMenuProvider without forcing all components through this single method override.
`open Unit`	`@MainThread onOptionsMenuClosed(menu: Menu)` This function is deprecated. `androidx.activity.ComponentActivity` now implements `MenuHost`, an interface that allows any component, including your activity itself, to add menu items by calling addMenuProvider without forcing all components through this single method override.
`open Unit`	`@MainThread @CallSuper onPause()` Called when the Fragment is no longer resumed.
`open Unit`	`onPictureInPictureModeChanged(isInPictureInPictureMode: Boolean)` Called by the system when the activity changes to and from picture-in-picture mode.
`open Unit`	`@MainThread onPrepareOptionsMenu(menu: Menu)` This function is deprecated. `androidx.activity.ComponentActivity` now implements `MenuHost`, an interface that allows any component, including your activity itself, to add menu items by calling addMenuProvider without forcing all components through this single method override.
`open Unit`	`@MainThread onPrimaryNavigationFragmentChanged( isPrimaryNavigationFragment: Boolean )` Callback for when the primary navigation state of this Fragment has changed.
`open Unit`	`onRequestPermissionsResult( requestCode: Int, permissions: Array<String>, grantResults: IntArray )` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`open Unit`	`@MainThread @CallSuper onResume()` Called when the fragment is visible to the user and actively running.
`open Unit`	`@MainThread @CallSuper onStart()` Called when the Fragment is visible to the user.
`open Unit`	`@MainThread @CallSuper onStop()` Called when the Fragment is no longer started.
`open Unit`	`@MainThread @CallSuper onViewStateRestored(savedInstanceState: Bundle?)` Called when all saved state has been restored into the view hierarchy of the fragment.
`open Unit`	`postponeEnterTransition()` Postpone the entering Fragment transition until `startPostponedEnterTransition` or `executePendingTransactions` has been called.
`Unit`	`postponeEnterTransition(duration: Long, timeUnit: TimeUnit)` Postpone the entering Fragment transition for a given amount of time and then call `startPostponedEnterTransition`.
`final ActivityResultLauncher<I>`	`@MainThread <I : Any, O : Any> registerForActivityResult( contract: ActivityResultContract<I, O>, callback: ActivityResultCallback<O> )` Register a request to `start an activity for result`, designated by the given `contract`.
`final ActivityResultLauncher<I>`	`@MainThread <I : Any, O : Any> registerForActivityResult( contract: ActivityResultContract<I, O>, registry: ActivityResultRegistry, callback: ActivityResultCallback<O> )` Register a request to `start an activity for result`, designated by the given `contract`.
`open Unit`	`registerForContextMenu(view: View)` Registers a context menu to be shown for the given view (multiple views can show the context menu).
`Unit`	`requestPermissions(permissions: Array<String>, requestCode: Int)` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`FragmentActivity`	`requireActivity()` Return the `FragmentActivity` this fragment is currently associated with.
`Bundle`	`requireArguments()` Return the arguments supplied when the fragment was instantiated.
`Context`	`requireContext()` Return the `Context` this fragment is currently associated with.
`FragmentManager`	`requireFragmentManager()` This function is deprecated. This has been renamed to `getParentFragmentManager()` to make it clear that you are accessing the FragmentManager that contains this Fragment and not the FragmentManager associated with child Fragments.
`Any`	`requireHost()` Return the host object of this fragment.
`Fragment`	`requireParentFragment()` Returns the parent Fragment containing this Fragment.
`View`	`requireView()` Get the root view for the fragment's layout (the one returned by `onCreateView`).
`open Unit`	`setAllowEnterTransitionOverlap(allow: Boolean)` Sets whether the the exit transition and enter transition overlap or not.
`open Unit`	`setAllowReturnTransitionOverlap(allow: Boolean)` Sets whether the the return transition and reenter transition overlap or not.
`open Unit`	`setArguments(args: Bundle?)` Supply the construction arguments for this fragment.
`open Unit`	`setEnterSharedElementCallback(callback: SharedElementCallback?)` When custom transitions are used with Fragments, the enter transition callback is called when this Fragment is attached or detached when not popping the back stack.
`open Unit`	`setEnterTransition(transition: Any?)` Sets the Transition that will be used to move Views into the initial scene.
`open Unit`	`setExitSharedElementCallback(callback: SharedElementCallback?)` When custom transitions are used with Fragments, the exit transition callback is called when this Fragment is attached or detached when popping the back stack.
`open Unit`	`setExitTransition(transition: Any?)` Sets the Transition that will be used to move Views out of the scene when the fragment is removed, hidden, or detached when not popping the back stack.
`open Unit`	`setHasOptionsMenu(hasMenu: Boolean)` This function is deprecated. This method is no longer needed when using a `MenuProvider` to provide a `Menu` to your activity, which replaces `onCreateOptionsMenu` as the recommended way to provide a consistent, optionally `Lifecycle`-aware, and modular way to handle menu creation and item selection.
`open Unit`	`setInitialSavedState(state: Fragment.SavedState?)` Set the initial saved state that this Fragment should restore itself from when first being constructed, as returned by `FragmentManager.saveFragmentInstanceState`.
`open Unit`	`setMenuVisibility(menuVisible: Boolean)` Set a hint for whether this fragment's menu should be visible.
`open Unit`	`setReenterTransition(transition: Any?)` Sets the Transition that will be used to move Views in to the scene when returning due to popping a back stack.
`open Unit`	`setRetainInstance(retain: Boolean)` This function is deprecated. Instead of retaining the Fragment itself, use a non-retained Fragment and keep retained state in a ViewModel attached to that Fragment.
`open Unit`	`setReturnTransition(transition: Any?)` Sets the Transition that will be used to move Views out of the scene when the Fragment is preparing to be removed, hidden, or detached because of popping the back stack.
`open Unit`	`setSharedElementEnterTransition(transition: Any?)` Sets the Transition that will be used for shared elements transferred into the content Scene.
`open Unit`	`setSharedElementReturnTransition(transition: Any?)` Sets the Transition that will be used for shared elements transferred back during a pop of the back stack.
`open Unit`	`setTargetFragment(fragment: Fragment?, requestCode: Int)` This function is deprecated. Instead of using a target fragment to pass results, the fragment requesting a result should use `setFragmentResultListener` to register a `FragmentResultListener` with a `requestKey` using its `parent fragment manager`.
`open Unit`	`setUserVisibleHint(isVisibleToUser: Boolean)` This function is deprecated. If you are manually calling this method, use `setMaxLifecycle` instead.
`open Boolean`	`shouldShowRequestPermissionRationale(permission: String)` Gets whether you should show UI with rationale before requesting a permission.
`open Unit`	`startActivity(intent: Intent)` Call startActivity from the fragment's containing Activity.
`open Unit`	`startActivity(intent: Intent, options: Bundle?)` Call startActivity from the fragment's containing Activity.
`open Unit`	`startActivityForResult(intent: Intent, requestCode: Int)` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`open Unit`	`startActivityForResult(intent: Intent, requestCode: Int, options: Bundle?)` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`open Unit`	`startIntentSenderForResult( intent: IntentSender, requestCode: Int, fillInIntent: Intent?, flagsMask: Int, flagsValues: Int, extraFlags: Int, options: Bundle? )` This function is deprecated. This method has been deprecated in favor of using the Activity Result API which brings increased type safety via an `ActivityResultContract` and the prebuilt contracts for common intents available in `androidx.activity.result.contract.ActivityResultContracts`, provides hooks for testing, and allow receiving results in separate, testable classes independent from your fragment.
`open Unit`	`startPostponedEnterTransition()` Begin postponed transitions after `postponeEnterTransition` was called.
`open String`	`toString()`
`open Unit`	`unregisterForContextMenu(view: View)` Prevents a context menu to be shown for the given view.

Inherited properties

From androidx.fragment.app.Fragment

`open CreationExtras`	`defaultViewModelCreationExtras` The `Fragment's arguments` when this is first called will be used as the defaults to any `androidx.lifecycle.SavedStateHandle` passed to a view model created using this extra.
`open ViewModelProvider.Factory`	`defaultViewModelProviderFactory`
`open Lifecycle`	`lifecycle` Overriding this method is no longer supported and this method will be made `final` in a future version of Fragment.
`final SavedStateRegistry`	`savedStateRegistry`
`open ViewModelStore`	`viewModelStore` Returns the `ViewModelStore` associated with this Fragment

Public companion functions

create

Added in 2.4.0

fun create(graphResId: @NavigationRes Int, startDestinationArgs: Bundle? = null): NavHostFragment

Create a new NavHostFragment instance with an inflated NavGraph resource.

Parameters
`graphResId: @NavigationRes Int`	Resource id of the navigation graph to inflate.
`startDestinationArgs: Bundle? = null`	Arguments to send to the start destination of the graph.

Returns
`NavHostFragment`	A new NavHostFragment instance.

findNavController

Added in 2.4.0

fun findNavController(fragment: Fragment): NavController

Find a NavController given a local Fragment.

This method will locate the NavController associated with this Fragment, looking first for a NavHostFragment along the given Fragment's parent chain. If a NavController is not found, this method will look for one along this Fragment's view hierarchy as specified by Navigation.findNavController.

Parameters
`fragment: Fragment`	the locally scoped Fragment for navigation

Returns
`NavController`	the locally scoped `NavController` for navigating from this `Fragment`

Throws
`kotlin.IllegalStateException`	if the given Fragment does not correspond with a `NavHost` or is not within a NavHost.

Public constructors

NavHostFragment

Added in 1.0.0

NavHostFragment()

Public functions

onAttach

@CallSuper
open fun onAttach(context: Context): Unit

Called when a fragment is first attached to its context. onCreate will be called after this.

onCreate

@CallSuper
open fun onCreate(savedInstanceState: Bundle?): Unit

Called to do initial creation of a fragment. This is called after onAttach and before onCreateView.

Note that this can be called while the fragment's activity is still in the process of being created. As such, you can not rely on things like the activity's content view hierarchy being initialized at this point. If you want to do work once the activity itself is created, add a androidx.lifecycle.LifecycleObserver on the activity's Lifecycle, removing it when it receives the CREATED callback.

Any restored child fragments will be created before the base Fragment.onCreate method returns.

Parameters
`savedInstanceState: Bundle?`	If the fragment is being re-created from a previous saved state, this is the state.

onCreateView

open fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View?

Called to have the fragment instantiate its user interface view. This is optional, and non-graphical fragments can return null. This will be called between onCreate and onViewCreated.

A default View can be returned by calling Fragment in your constructor. Otherwise, this method returns null.

It is recommended to only inflate the layout in this method and move logic that operates on the returned View to onViewCreated.

If you return a View from here, you will later be called in onDestroyView when the view is being released.

Parameters
`inflater: LayoutInflater`	The LayoutInflater object that can be used to inflate any views in the fragment,
`container: ViewGroup?`	If non-null, this is the parent view that the fragment's UI should be attached to. The fragment should not add the view itself, but this can be used to generate the LayoutParams of the view.
`savedInstanceState: Bundle?`	If non-null, this fragment is being re-constructed from a previous saved state as given here.

Returns
`View?`	Return the View for the fragment's UI, or null.

onDestroyView

open fun onDestroyView(): Unit

Called when the view previously created by onCreateView has been detached from the fragment. The next time the fragment needs to be displayed, a new view will be created. This is called after onStop and before onDestroy. It is called regardless of whether onCreateView returned a non-null view. Internally it is called after the view's state has been saved but before it has been removed from its parent.

onInflate

@CallSuper
open fun onInflate(
    context: Context,
    attrs: AttributeSet,
    savedInstanceState: Bundle?
): Unit

Called when a fragment is being created as part of a view layout inflation, typically from setting the content view of an activity. This may be called immediately after the fragment is created from a FragmentContainerView in a layout file. Note this is before the fragment's onAttach has been called; all you should do here is parse the attributes and save them away.

This is called the first time the fragment is inflated. If it is being inflated into a new instance with saved state, this method will not be called a second time for the restored state fragment.

Here is a typical implementation of a fragment that can take parameters both through attributes supplied here as well from getArguments:

public static class MyFragment extends Fragment {
    CharSequence mLabel;

    /**
     * Create a new instance of MyFragment that will be initialized
     * with the given arguments.
     */
    static MyFragment newInstance(CharSequence label) {
        MyFragment f = new MyFragment();
        Bundle b = new Bundle();
        b.putCharSequence("label", label);
        f.setArguments(b);
        return f;
    }

    /**
     * Parse attributes during inflation from a view hierarchy into the
     * arguments we handle.
     */
    @Override
    public void onInflate(@NonNull Context context, @NonNull AttributeSet attrs,
            @Nullable Bundle savedInstanceState) {
        super.onInflate(context, attrs, savedInstanceState);

        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.FragmentArguments);
        mLabel = a.getText(R.styleable.FragmentArguments_android_label);
        a.recycle();
    }

    /**
     * During creation, if arguments have been supplied to the fragment
     * then parse those out.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Bundle args = getArguments();
        if (args != null) {
            CharSequence label = args.getCharSequence("label");
            if (label != null) {
                mLabel = label;
            }
        }
    }

    /**
     * Create the view for this fragment, using the arguments given to it.
     */
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.hello_world, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText(mLabel != null ? mLabel : "(no label)");
        ViewCompat.setBackground(
                tv, ContextCompat.getDrawable(getContext(), android.R.drawable.gallery_thumb));
        return v;
    }
}

Note that parsing the XML attributes uses a "styleable" resource. The declaration for the styleable used here is:

<declare-styleable name="FragmentArguments">
    <attr name="android:label" />
</declare-styleable>

The fragment can then be declared within its activity's content layout through a tag like this:

<androidx.fragment.app.FragmentContainerView
        class="com.example.android.supportv4.app.FragmentArgumentsSupport$MyFragment"
        android:id="@+id/embedded"
        android:layout_width="0px" android:layout_height="wrap_content"
        android:layout_weight="1"
        android:label="@string/fragment_arguments_embedded" />

This fragment can also be created dynamically from arguments given at runtime in the arguments Bundle; here is an example of doing so at creation of the containing activity:

@Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_arguments_support);

    if (savedInstanceState == null) {
        // First-time init; create fragment to embed in activity.
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        Fragment newFragment = MyFragment.newInstance("From Arguments");
        ft.add(R.id.created, newFragment);
        ft.commit();
    }
}

Parameters
`context: Context`	The Activity that is inflating this fragment.
`attrs: AttributeSet`	The attributes at the tag where the fragment is being created.
`savedInstanceState: Bundle?`	If the fragment is being re-created from a previous saved state, this is the state.

onSaveInstanceState

@CallSuper
open fun onSaveInstanceState(outState: Bundle): Unit

Called to ask the fragment to save its current dynamic state, so it can later be reconstructed in a new instance if its process is restarted. If a new instance of the fragment later needs to be created, the data you place in the Bundle here will be available in the Bundle given to onCreate, onCreateView, and onViewCreated.

This corresponds to Activity.onSaveInstanceState(Bundle) and most of the discussion there applies here as well. Note however: this method may be called at any time before onDestroy. There are many situations where a fragment may be mostly torn down (such as when placed on the back stack with no UI showing), but its state will not be saved until its owning activity actually needs to save its state.

Parameters
`outState: Bundle`	Bundle in which to place your saved state.

onViewCreated

open fun onViewCreated(view: View, savedInstanceState: Bundle?): Unit

Called immediately after onCreateView has returned, but before any saved state has been restored in to the view. This gives subclasses a chance to initialize themselves once they know their view hierarchy has been completely created. The fragment's view hierarchy is not however attached to its parent at this point.

Parameters
`view: View`	The View returned by `onCreateView`.
`savedInstanceState: Bundle?`	If non-null, this fragment is being re-constructed from a previous saved state as given here.

Protected functions

createFragmentNavigator

Added in 1.0.0

Deprecated in 2.1.0

protected open fun createFragmentNavigator(): Navigator<FragmentNavigator.Destination>

Create the FragmentNavigator that this NavHostFragment will use. By default, this uses FragmentNavigator, which replaces the entire contents of the NavHostFragment.

This is only called once in onCreate and should not be called directly by subclasses.

Returns
`Navigator<FragmentNavigator.Destination>`	a new instance of a FragmentNavigator

Added in 2.1.0

Deprecated in 2.4.0

@CallSuper
protected open fun onCreateNavController(navController: NavController): Unit

Callback for when the getNavController is created. If you support any custom destination types, their Navigator should be added here to ensure it is available before the navigation graph is inflated / set.

By default, this adds a DialogFragmentNavigator and FragmentNavigator.

This is only called once when the navController is called. This will be called in onCreate if the navController has not yet been called. This should not be called directly by subclasses.

Parameters
`navController: NavController`	The newly created `NavController`.

Added in 2.4.0

@CallSuper
protected open fun onCreateNavHostController(navHostController: NavHostController): Unit

Callback for when the NavHostController is created. If you support any custom destination types, their Navigator should be added here to ensure it is available before the navigation graph is inflated / set.

This provides direct access to the host specific methods available on NavHostController such as NavHostController.setOnBackPressedDispatcher.

By default, this adds a DialogFragmentNavigator and FragmentNavigator.

This is only called once when the navController is called. This will be called in onCreate if the navController has not yet been called. This should not be called directly by subclasses.

Parameters
`navHostController: NavHostController`	The newly created `NavHostController` that will be returned by getNavController after

Public properties

navController

Added in 1.0.0

final val navController: NavController

The navigation controller for this navigation host. This method will return null until this host fragment's onCreate has been called and it has had an opportunity to restore from a previous instance state.

Returns
`NavController`	this host's navigation controller

Throws
`kotlin.IllegalStateException`	if called before `onCreate`