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FragmentManager

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abstract class FragmentManager : FragmentResultOwner


Static library support version of the framework's android.app.FragmentManager. Used to write apps that run on platforms prior to Android 3.0. When running on Android 3.0 or above, this implementation is still used; it does not try to switch to the framework's implementation. See the framework FragmentManager documentation for a class overview.

Your activity must derive from FragmentActivity to use this. From such an activity, you can acquire the FragmentManager by calling FragmentActivity#getSupportFragmentManager.

Summary

Nested types

FragmentManager.BackStackEntry

Representation of an entry on the fragment back stack, as created with FragmentTransaction.addToBackStack().

FragmentManager.FragmentLifecycleCallbacks

Callback interface for listening to fragment state changes that happen within a given FragmentManager.

FragmentManager.OnBackStackChangedListener

Interface to watch for changes to the back stack.

Constants

Int

Flag for popBackStack and popBackStack: If set, and the name or ID of a back stack entry has been supplied, then all matching entries will be consumed until one that doesn't match is found or the bottom of the stack is reached.

Public constructors

Public functions

Unit

Add a FragmentOnAttachListener that should receive a call to FragmentOnAttachListener#onAttachFragment(FragmentManager, Fragment) when a new Fragment is attached to this FragmentManager.

Unit

Add a new listener for changes to the fragment back stack.

FragmentTransaction

Start a series of edit operations on the Fragments associated with this FragmentManager.

Unit

Clears the stored result for the given requestKey.

Unit

Clears the stored FragmentResultListener for the given requestKey.

Unit
dump(
    prefix: String,
    fd: FileDescriptor?,
    writer: PrintWriter,
    args: Array<String>?
)

Print the FragmentManager's state into the given stream.

Unit

This function is deprecated.

FragmentManager now respects Log#isLoggable(String, int) for debug logging, allowing you to use adb shell setprop log.tag.FragmentManager VERBOSE.

@FragmentStateManagerControl Unit

Control whether FragmentManager uses the new state manager that is responsible for:

Boolean

After a FragmentTransaction is committed with FragmentTransaction.commit(), it is scheduled to be executed asynchronously on the process's main thread.

F
<F : Fragment?> findFragment(view: View)

Find a Fragment associated with the given View.

Fragment?

Finds a fragment that was identified by the given id either when inflated from XML or as the container ID when added in a transaction.

Fragment?

Finds a fragment that was identified by the given tag either when inflated from XML or as supplied when added in a transaction.

FragmentManager.BackStackEntry

Return the BackStackEntry at index index in the back stack; entries start index 0 being the bottom of the stack.

Int

Return the number of entries currently in the back stack.

Fragment?
getFragment(bundle: Bundle, key: String)

Retrieve the current Fragment instance for a reference previously placed with putFragment.

FragmentFactory

Gets the current FragmentFactory used to instantiate new Fragment instances.

List<Fragment>

Get a list of all fragments that are currently added to the FragmentManager.

Fragment?

Return the currently active primary navigation fragment for this FragmentManager.

Boolean

Returns true if the final Activity.onDestroy() call has been made on the FragmentManager's Activity, so this instance is now dead.

Boolean

Returns {@code true} if the FragmentManager's state has already been saved by its host.

Unit

Pop the top state off the back stack.

Unit
popBackStack(name: String?, flags: Int)

Pop the last fragment transition from the manager's fragment back stack.

Unit
popBackStack(id: Int, flags: Int)

Pop all back stack states up to the one with the given identifier.

Boolean

Like popBackStack, but performs the operation immediately inside of the call.

Boolean
popBackStackImmediate(name: String?, flags: Int)

Like popBackStack, but performs the operation immediately inside of the call.

Boolean
popBackStackImmediate(id: Int, flags: Int)

Like popBackStack, but performs the operation immediately inside of the call.

Unit
putFragment(bundle: Bundle, key: String, fragment: Fragment)

Put a reference to a fragment in a Bundle.

Unit

Registers a FragmentLifecycleCallbacks to listen to fragment lifecycle events happening in this FragmentManager.

Unit

Remove a FragmentOnAttachListener that was previously added via addFragmentOnAttachListener.

Unit

Remove a listener that was previously added with addOnBackStackChangedListener.

Fragment.SavedState?

Save the current instance state of the given Fragment.

Unit

Set a FragmentFactory for this FragmentManager that will be used to create new Fragment instances from this point onward.

Unit
setFragmentResult(requestKey: String, result: Bundle)

Sets the given result for the requestKey.

Unit
setFragmentResultListener(
    requestKey: String,
    lifecycleOwner: LifecycleOwner,
    listener: FragmentResultListener
)

Sets the FragmentResultListener for a given requestKey.

String
Unit

Unregisters a previously registered FragmentLifecycleCallbacks.

Constants

POP_BACK_STACK_INCLUSIVE

val POP_BACK_STACK_INCLUSIVEInt

Flag for popBackStack and popBackStack: If set, and the name or ID of a back stack entry has been supplied, then all matching entries will be consumed until one that doesn't match is found or the bottom of the stack is reached. Otherwise, all entries up to but not including that entry will be removed.

Public constructors

FragmentManager

FragmentManager()

Public functions

addFragmentOnAttachListener

fun addFragmentOnAttachListener(listener: FragmentOnAttachListener): Unit

Add a FragmentOnAttachListener that should receive a call to FragmentOnAttachListener#onAttachFragment(FragmentManager, Fragment) when a new Fragment is attached to this FragmentManager.

Parameters
listener: FragmentOnAttachListener

Listener to add

addOnBackStackChangedListener

fun addOnBackStackChangedListener(
    listener: FragmentManager.OnBackStackChangedListener
): Unit

Add a new listener for changes to the fragment back stack.

beginTransaction

fun beginTransaction(): FragmentTransaction

Start a series of edit operations on the Fragments associated with this FragmentManager.

Note: A fragment transaction can only be created/committed prior to an activity saving its state. If you try to commit a transaction after FragmentActivity.onSaveInstanceState() (and prior to a following FragmentActivity.onStart or FragmentActivity.onResume(), you will get an error. This is because the framework takes care of saving your current fragments in the state, and if changes are made after the state is saved then they will be lost.

clearFragmentResult

fun clearFragmentResult(requestKey: String): Unit

Clears the stored result for the given requestKey. This clears any result that was previously set via setFragmentResult that hasn't yet been delivered to a FragmentResultListener.

Parameters
requestKey: String

key used to identify the result

clearFragmentResultListener

fun clearFragmentResultListener(requestKey: String): Unit

Clears the stored FragmentResultListener for the given requestKey. This clears any FragmentResultListener that was previously set via setFragmentResultListener.

Parameters
requestKey: String

key used to identify the result

dump

fun dump(
    prefix: String,
    fd: FileDescriptor?,
    writer: PrintWriter,
    args: Array<String>?
): Unit

Print the FragmentManager's state into the given stream.

Parameters
prefix: String

Text to print at the front of each line.

fd: FileDescriptor?

The raw file descriptor that the dump is being sent to.

writer: PrintWriter

A PrintWriter to which the dump is to be set.

args: Array<String>?

Additional arguments to the dump request.

enableDebugLogging

fun enableDebugLogging(enabled: Boolean): Unit

Control whether the framework's internal fragment manager debugging logs are turned on. If enabled, you will see output in logcat as the framework performs fragment operations.

See also
Log

android.util.Log#isLoggable(String, int)

enableNewStateManager

@FragmentStateManagerControl
fun enableNewStateManager(enabled: Boolean): @FragmentStateManagerControl Unit

Control whether FragmentManager uses the new state manager that is responsible for:

This must only be changed before any fragment transactions are done (i.e., in your Application class or prior to super.onCreate()in every activity with the same value for all activities). Changing it after that point is not supported and can result in fragments not moving to their expected state.

This is enabled by default. Disabling it should only be used in cases where you are debugging a potential regression and as part of filing an issue to verify and fix the regression.

Parameters
enabled: Boolean

Whether the new state manager should be enabled.

executePendingTransactions

fun executePendingTransactions(): Boolean

After a FragmentTransaction is committed with FragmentTransaction.commit(), it is scheduled to be executed asynchronously on the process's main thread. If you want to immediately executing any such pending operations, you can call this function (only from the main thread) to do so. Note that all callbacks and other related behavior will be done from within this call, so be careful about where this is called from.

If you are committing a single transaction that does not modify the fragment back stack, strongly consider using FragmentTransaction#commitNow() instead. This can help avoid unwanted side effects when other code in your app has pending committed transactions that expect different timing.

This also forces the start of any postponed Transactions where Fragment#postponeEnterTransition() has been called.

Returns
Boolean

Returns true if there were any pending transactions to be executed.

findFragment

fun <F : Fragment?> findFragment(view: View): F

Find a Fragment associated with the given View. This method will locate the Fragment associated with this view. This is automatically populated for the View returned by Fragment#onCreateView and its children.

Parameters
view: View

the view to search from

Returns
F

the locally scoped Fragment to the given view

Throws
java.lang.IllegalStateException

if the given view does not correspond with a Fragment.

findFragmentById

fun findFragmentById(id: Int): Fragment?

Finds a fragment that was identified by the given id either when inflated from XML or as the container ID when added in a transaction. This first searches through fragments that are currently added to the manager's activity; if no such fragment is found, then all fragments currently on the back stack associated with this ID are searched.

Returns
Fragment?

The fragment if found or null otherwise.

findFragmentByTag

fun findFragmentByTag(tag: String?): Fragment?

Finds a fragment that was identified by the given tag either when inflated from XML or as supplied when added in a transaction. This first searches through fragments that are currently added to the manager's activity; if no such fragment is found, then all fragments currently on the back stack are searched.

If provided a {@code null} tag, this method returns null.

Parameters
tag: String?

the tag used to search for the fragment

Returns
Fragment?

The fragment if found or null otherwise.

getBackStackEntryAt

fun getBackStackEntryAt(index: Int): FragmentManager.BackStackEntry

Return the BackStackEntry at index index in the back stack; entries start index 0 being the bottom of the stack.

getBackStackEntryCount

fun getBackStackEntryCount(): Int

Return the number of entries currently in the back stack.

getFragment

fun getFragment(bundle: Bundle, key: String): Fragment?

Retrieve the current Fragment instance for a reference previously placed with putFragment.

Parameters
bundle: Bundle

The bundle from which to retrieve the fragment reference.

key: String

The name of the entry in the bundle.

Returns
Fragment?

Returns the current Fragment instance that is associated with the given reference.

getFragmentFactory

fun getFragmentFactory(): FragmentFactory

Gets the current FragmentFactory used to instantiate new Fragment instances.

If no factory has been explicitly set on this FragmentManager via setFragmentFactory, the FragmentFactory of the parent FragmentManager will be returned.

Returns
FragmentFactory

the current FragmentFactory

getFragments

fun getFragments(): List<Fragment>

Get a list of all fragments that are currently added to the FragmentManager. This may include those that are hidden as well as those that are shown. This will not include any fragments only in the back stack, or fragments that are detached or removed.

The order of the fragments in the list is the order in which they were added or attached.

Returns
List<Fragment>

A list of all fragments that are added to the FragmentManager.

getPrimaryNavigationFragment

fun getPrimaryNavigationFragment(): Fragment?

Return the currently active primary navigation fragment for this FragmentManager. The primary navigation fragment is set by fragment transactions using FragmentTransaction#setPrimaryNavigationFragment(Fragment).

The primary navigation fragment's child FragmentManager will be called first to process delegated navigation actions such as popBackStack if no ID or transaction name is provided to pop to.

Returns
Fragment?

the fragment designated as the primary navigation fragment

isDestroyed

fun isDestroyed(): Boolean

Returns true if the final Activity.onDestroy() call has been made on the FragmentManager's Activity, so this instance is now dead.

isStateSaved

fun isStateSaved(): Boolean

Returns {@code true} if the FragmentManager's state has already been saved by its host. Any operations that would change saved state should not be performed if this method returns true. For example, any popBackStack() method, such as popBackStackImmediate or any FragmentTransaction using FragmentTransaction#commit() instead of FragmentTransaction#commitAllowingStateLoss() will change the state and will result in an error.

Returns
Boolean

true if this FragmentManager's state has already been saved by its host

popBackStack

fun popBackStack(): Unit

Pop the top state off the back stack. This function is asynchronous -- it enqueues the request to pop, but the action will not be performed until the application returns to its event loop.

popBackStack

fun popBackStack(name: String?, flags: Int): Unit

Pop the last fragment transition from the manager's fragment back stack. This function is asynchronous -- it enqueues the request to pop, but the action will not be performed until the application returns to its event loop.

Parameters
name: String?

If non-null, this is the name of a previous back state to look for; if found, all states up to that state will be popped. The POP_BACK_STACK_INCLUSIVE flag can be used to control whether the named state itself is popped. If null, only the top state is popped.

flags: Int

Either 0 or POP_BACK_STACK_INCLUSIVE.

popBackStack

fun popBackStack(id: Int, flags: Int): Unit

Pop all back stack states up to the one with the given identifier. This function is asynchronous -- it enqueues the request to pop, but the action will not be performed until the application returns to its event loop.

Parameters
id: Int

Identifier of the stated to be popped. If no identifier exists, false is returned. The identifier is the number returned by FragmentTransaction.commit(). The POP_BACK_STACK_INCLUSIVE flag can be used to control whether the named state itself is popped.

flags: Int

Either 0 or POP_BACK_STACK_INCLUSIVE.

popBackStackImmediate

fun popBackStackImmediate(): Boolean

Like popBackStack, but performs the operation immediately inside of the call. This is like calling executePendingTransactions afterwards without forcing the start of postponed Transactions.

Returns
Boolean

Returns true if there was something popped, else false.

popBackStackImmediate

fun popBackStackImmediate(name: String?, flags: Int): Boolean

Like popBackStack, but performs the operation immediately inside of the call. This is like calling executePendingTransactions afterwards without forcing the start of postponed Transactions.

Returns
Boolean

Returns true if there was something popped, else false.

popBackStackImmediate

fun popBackStackImmediate(id: Int, flags: Int): Boolean

Like popBackStack, but performs the operation immediately inside of the call. This is like calling executePendingTransactions afterwards without forcing the start of postponed Transactions.

Returns
Boolean

Returns true if there was something popped, else false.

putFragment

fun putFragment(bundle: Bundle, key: String, fragment: Fragment): Unit

Put a reference to a fragment in a Bundle. This Bundle can be persisted as saved state, and when later restoring getFragment will return the current instance of the same fragment.

Parameters
bundle: Bundle

The bundle in which to put the fragment reference.

key: String

The name of the entry in the bundle.

fragment: Fragment

The Fragment whose reference is to be stored.

registerFragmentLifecycleCallbacks

fun registerFragmentLifecycleCallbacks(
    cb: FragmentManager.FragmentLifecycleCallbacks,
    recursive: Boolean
): Unit

Registers a FragmentLifecycleCallbacks to listen to fragment lifecycle events happening in this FragmentManager. All registered callbacks will be automatically unregistered when this FragmentManager is destroyed.

Parameters
cb: FragmentManager.FragmentLifecycleCallbacks

Callbacks to register

recursive: Boolean

true to automatically register this callback for all child FragmentManagers

removeFragmentOnAttachListener

fun removeFragmentOnAttachListener(listener: FragmentOnAttachListener): Unit

Remove a FragmentOnAttachListener that was previously added via addFragmentOnAttachListener. It will no longer get called when a new Fragment is attached.

Parameters
listener: FragmentOnAttachListener

Listener to remove

removeOnBackStackChangedListener

fun removeOnBackStackChangedListener(
    listener: FragmentManager.OnBackStackChangedListener
): Unit

Remove a listener that was previously added with addOnBackStackChangedListener.

saveFragmentInstanceState

fun saveFragmentInstanceState(fragment: Fragment): Fragment.SavedState?

Save the current instance state of the given Fragment. This can be used later when creating a new instance of the Fragment and adding it to the fragment manager, to have it create itself to match the current state returned here. Note that there are limits on how this can be used:

Parameters
fragment: Fragment

The Fragment whose state is to be saved.

Returns
Fragment.SavedState?

The generated state. This will be null if there was no interesting state created by the fragment.

setFragmentFactory

fun setFragmentFactory(fragmentFactory: FragmentFactory): Unit

Set a FragmentFactory for this FragmentManager that will be used to create new Fragment instances from this point onward.

The child FragmentManager of all Fragments in this FragmentManager will also use this factory if one is not explicitly set.

Parameters
fragmentFactory: FragmentFactory

the factory to use to create new Fragment instances

See also
getFragmentFactory

#getFragmentFactory()

setFragmentResult

fun setFragmentResult(requestKey: String, result: Bundle): Unit

Sets the given result for the requestKey. This result will be delivered to a FragmentResultListener that is called given to setFragmentResultListener with the same requestKey. If no FragmentResultListener with the same key is set or the Lifecycle associated with the listener is not at least STARTED, the result is stored until one becomes available, or clearFragmentResult is called with the same requestKey.

Parameters
requestKey: String

key used to identify the result

result: Bundle

the result to be passed to another fragment

setFragmentResultListener

fun setFragmentResultListener(
    requestKey: String,
    lifecycleOwner: LifecycleOwner,
    listener: FragmentResultListener
): Unit

Sets the FragmentResultListener for a given requestKey. Once the given LifecycleOwner is at least in the STARTED state, any results set by setFragmentResult using the same requestKey will be delivered to the callback. The callback will remain active until the LifecycleOwner reaches the DESTROYED state or clearFragmentResultListener is called with the same requestKey.

Parameters
requestKey: String

requestKey used to identify the result

lifecycleOwner: LifecycleOwner

lifecycleOwner for handling the result

listener: FragmentResultListener

listener for result changes

toString

fun toString(): String

unregisterFragmentLifecycleCallbacks

fun unregisterFragmentLifecycleCallbacks(
    cb: FragmentManager.FragmentLifecycleCallbacks
): Unit

Unregisters a previously registered FragmentLifecycleCallbacks. If the callback was not previously registered this call has no effect. All registered callbacks will be automatically unregistered when this FragmentManager is destroyed.

Parameters
cb: FragmentManager.FragmentLifecycleCallbacks

Callbacks to unregister