FragmentManager
public abstract class FragmentManager implements 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 getSupportFragmentManager.
Summary
Nested types |
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public interface FragmentManager.BackStackEntryRepresentation of an entry on the fragment back stack, as created with |
public abstract class FragmentManager.FragmentLifecycleCallbacksCallback interface for listening to fragment state changes that happen within a given FragmentManager. |
public interface FragmentManager.OnBackStackChangedListenerInterface to watch for changes to the back stack. |
Constants |
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static final int |
Flag for |
Public constructors |
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Public methods |
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void |
Add a |
void |
Add a new listener for changes to the fragment back stack. |
@NonNull FragmentTransaction |
Start a series of edit operations on the Fragments associated with this FragmentManager. |
void |
clearBackStack(@NonNull String name)Clears the back stack previously saved via |
final void |
clearFragmentResult(@NonNull String requestKey)Clears the stored result for the given requestKey. |
final void |
clearFragmentResultListener(@NonNull String requestKey)Clears the stored |
void |
dump(Print the FragmentManager's state into the given stream. |
static void |
This method is deprecated. FragmentManager now respects |
static void |
@PredictiveBackControlControl whether FragmentManager uses the new state predictive back feature that allows seeing the previous Fragment when using gesture back. |
boolean |
After a |
static @NonNull F |
<F extends Fragment> findFragment(@NonNull View view) |
@Nullable Fragment |
findFragmentById(@IdRes int id)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. |
@Nullable Fragment |
findFragmentByTag(@Nullable String tag)Finds a fragment that was identified by the given tag either when inflated from XML or as supplied when added in a transaction. |
static @NonNull FragmentManager |
findFragmentManager(@NonNull View view)Recurse up the view hierarchy, looking for a FragmentManager |
@NonNull FragmentManager.BackStackEntry |
getBackStackEntryAt(int index)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. |
@Nullable Fragment |
getFragment(@NonNull Bundle bundle, @NonNull String key)Retrieve the current Fragment instance for a reference previously placed with |
@NonNull FragmentFactory |
Gets the current |
@NonNull List<Fragment> |
Get a list of all fragments that are currently added to the FragmentManager. |
@Nullable Fragment |
Return the currently active primary navigation fragment for this FragmentManager. |
@Nullable FragmentStrictMode.Policy |
Returns the current policy for this FragmentManager. |
boolean |
Returns true if the final |
boolean |
Returns |
final void |
onContainerAvailable(@NonNull FragmentContainerView container)Callback for when the |
void |
Pop the top state off the back stack. |
void |
popBackStack(int id, int flags)Pop all back stack states up to the one with the given identifier. |
void |
popBackStack(@Nullable String name, int flags)Pop the last fragment transition from the manager's fragment back stack. |
boolean |
Like |
boolean |
popBackStackImmediate(int id, int flags)Like |
boolean |
@MainThreadLike |
void |
Put a reference to a fragment in a Bundle. |
void |
registerFragmentLifecycleCallbacks(Registers a |
void |
Remove a |
void |
Remove a listener that was previously added with |
void |
restoreBackStack(@NonNull String name)Restores the back stack previously saved via |
void |
saveBackStack(@NonNull String name)Save the back stack. |
@Nullable Fragment.SavedState |
saveFragmentInstanceState(@NonNull Fragment fragment)Save the current instance state of the given Fragment. |
void |
setFragmentFactory(@NonNull FragmentFactory fragmentFactory)Set a |
final void |
setFragmentResult(@NonNull String requestKey, @NonNull Bundle result)Sets the given result for the requestKey. |
final void |
setFragmentResultListener(Sets the |
void |
Sets the policy for what actions should be detected, as well as the penalty if such actions occur. |
@NonNull String |
toString() |
void |
Unregisters a previously registered |
Extension functions |
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final void |
FragmentManagerKt.commit(Run |
final void |
@MainThreadRun |
final void |
FragmentManagerKt.This method is deprecated. Use commit { .. } or commitNow { .. } extensions |
Constants
POP_BACK_STACK_INCLUSIVE
public static final int POP_BACK_STACK_INCLUSIVE = 1
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
Public methods
addFragmentOnAttachListener
public void addFragmentOnAttachListener(@NonNull FragmentOnAttachListener listener)
Add a FragmentOnAttachListener that should receive a call to onAttachFragment when a new Fragment is attached to this FragmentManager.
| Parameters | |
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@NonNull FragmentOnAttachListener listener |
Listener to add |
addOnBackStackChangedListener
public void addOnBackStackChangedListener(
@NonNull FragmentManager.OnBackStackChangedListener listener
)
Add a new listener for changes to the fragment back stack.
beginTransaction
public @NonNull FragmentTransaction beginTransaction()
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.
clearBackStack
public void clearBackStack(@NonNull String name)
Clears the back stack previously saved via saveBackStack. This will result in all of the transactions that made up that back stack to be thrown away, thus destroying any fragments that were added through those transactions. All state of those fragments will be cleared as part of this process. If no state was previously saved with the given name, this operation does nothing.
This function is asynchronous -- it enqueues the request to clear, but the action will not be performed until the application returns to its event loop.
| Parameters | |
|---|---|
@NonNull String name |
The name of the back stack previously saved by |
clearFragmentResult
public final void clearFragmentResult(@NonNull String requestKey)
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.
clearFragmentResultListener
public final void clearFragmentResultListener(@NonNull String requestKey)
Clears the stored FragmentResultListener for the given requestKey. This clears any FragmentResultListener that was previously set via setFragmentResultListener.
dump
public void dump(
@NonNull String prefix,
@Nullable FileDescriptor fd,
@NonNull PrintWriter writer,
@Nullable String[] args
)
Print the FragmentManager's state into the given stream.
| Parameters | |
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@NonNull String prefix |
Text to print at the front of each line. |
@Nullable FileDescriptor fd |
The raw file descriptor that the dump is being sent to. |
@NonNull PrintWriter writer |
A PrintWriter to which the dump is to be set. |
@Nullable String[] args |
Additional arguments to the dump request. |
public static void enableDebugLogging(boolean enabled)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 | |
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isLoggable |
enablePredictiveBack
@PredictiveBackControl
public static void enablePredictiveBack(boolean enabled)
Control whether FragmentManager uses the new state predictive back feature that allows seeing the previous Fragment when using gesture back.
This should only be changed before any fragment transactions are done (i.e., in your Application class or prior to super.onCreate() in every activity).
| Parameters | |
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boolean enabled |
Whether predictive back should be enabled. |
executePendingTransactions
@MainThread
public boolean executePendingTransactions()
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 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 postponeEnterTransition has been called.
| Returns | |
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boolean |
Returns true if there were any pending transactions to be executed. |
findFragment
public static @NonNull F <F extends Fragment> findFragment(@NonNull View view)
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 onCreateView and its children.
| Throws | |
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java.lang.IllegalStateException |
if the given view does not correspond with a |
findFragmentById
public @Nullable Fragment findFragmentById(@IdRes int id)
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.
findFragmentByTag
public @Nullable Fragment findFragmentByTag(@Nullable String tag)
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 null tag, this method returns null.
findFragmentManager
public static @NonNull FragmentManager findFragmentManager(@NonNull View view)
Recurse up the view hierarchy, looking for a FragmentManager
| Returns | |
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@NonNull FragmentManager |
The containing |
| Throws | |
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java.lang.IllegalStateException |
if there no Fragment associated with the view and the view's context is not a |
getBackStackEntryAt
public @NonNull FragmentManager.BackStackEntry getBackStackEntryAt(int index)
Return the BackStackEntry at index index in the back stack; entries start index 0 being the bottom of the stack.
getBackStackEntryCount
public int getBackStackEntryCount()
Return the number of entries currently in the back stack.
getFragment
public @Nullable Fragment getFragment(@NonNull Bundle bundle, @NonNull String key)
Retrieve the current Fragment instance for a reference previously placed with putFragment.
getFragmentFactory
public @NonNull FragmentFactory getFragmentFactory()
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 | |
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@NonNull FragmentFactory |
the current FragmentFactory |
getFragments
public @NonNull List<Fragment> getFragments()
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.
getPrimaryNavigationFragment
public @Nullable Fragment getPrimaryNavigationFragment()
Return the currently active primary navigation fragment for this FragmentManager. The primary navigation fragment is set by fragment transactions using setPrimaryNavigationFragment.
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.
getStrictModePolicy
public @Nullable FragmentStrictMode.Policy getStrictModePolicy()
Returns the current policy for this FragmentManager. If no policy is set, returns null.
isDestroyed
public boolean isDestroyed()
Returns true if the final Activity.onDestroy() call has been made on the FragmentManager's Activity, so this instance is now dead.
isStateSaved
public boolean isStateSaved()
Returns 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 commit instead of commitAllowingStateLoss will change the state and will result in an error.
| Returns | |
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boolean |
true if this FragmentManager's state has already been saved by its host |
onContainerAvailable
public final void onContainerAvailable(@NonNull FragmentContainerView container)
Callback for when the FragmentContainerView becomes available in the view hierarchy and the fragment manager can add the fragment view to its hierarchy.
| Parameters | |
|---|---|
@NonNull FragmentContainerView container |
the container that the active fragment should add their views to |
popBackStack
public void popBackStack()
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
public void popBackStack(int id, int flags)
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 | |
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int id |
Identifier of the stated to be popped. If no identifier exists, false is returned. The identifier is the number returned by |
int flags |
Either 0 or |
popBackStack
public void popBackStack(@Nullable String name, int flags)
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 | |
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@Nullable String name |
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 |
int flags |
Either 0 or |
popBackStackImmediate
@MainThread
public boolean popBackStackImmediate()
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 | |
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boolean |
Returns true if there was something popped, else false. |
popBackStackImmediate
public boolean popBackStackImmediate(int id, int flags)
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
@MainThread
public boolean popBackStackImmediate(@Nullable String name, int flags)
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
public void putFragment(
@NonNull Bundle bundle,
@NonNull String key,
@NonNull Fragment fragment
)
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.
registerFragmentLifecycleCallbacks
public void registerFragmentLifecycleCallbacks(
@NonNull FragmentManager.FragmentLifecycleCallbacks cb,
boolean recursive
)
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 | |
|---|---|
@NonNull FragmentManager.FragmentLifecycleCallbacks cb |
Callbacks to register |
boolean recursive |
true to automatically register this callback for all child FragmentManagers |
removeFragmentOnAttachListener
public void removeFragmentOnAttachListener(
@NonNull FragmentOnAttachListener listener
)
Remove a FragmentOnAttachListener that was previously added via addFragmentOnAttachListener. It will no longer get called when a new Fragment is attached.
| Parameters | |
|---|---|
@NonNull FragmentOnAttachListener listener |
Listener to remove |
removeOnBackStackChangedListener
public void removeOnBackStackChangedListener(
@NonNull FragmentManager.OnBackStackChangedListener listener
)
Remove a listener that was previously added with addOnBackStackChangedListener.
restoreBackStack
public void restoreBackStack(@NonNull String name)
Restores the back stack previously saved via saveBackStack. This will result in all of the transactions that made up that back stack to be re-executed, thus re-adding any fragments that were added through those transactions. All state of those fragments will be restored as part of this process. If no state was previously saved with the given name, this operation does nothing.
This function is asynchronous -- it enqueues the request to restore, but the action will not be performed until the application returns to its event loop.
| Parameters | |
|---|---|
@NonNull String name |
The name of the back stack previously saved by |
saveBackStack
public void saveBackStack(@NonNull String name)
Save the back stack. While this functions similarly to popBackStack, it does not throw away the state of any fragments that were added through those transactions. Instead, the back stack that is saved by this method can later be restored with its state in tact.
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 | |
|---|---|
@NonNull String name |
The name set by |
saveFragmentInstanceState
public @Nullable Fragment.SavedState saveFragmentInstanceState(@NonNull Fragment fragment)
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:
- The Fragment must currently be attached to the FragmentManager.
- A new Fragment created using this saved state must be the same class type as the Fragment it was created from.
- The saved state can not contain dependencies on other fragments -- that is it can't use
putFragmentto store a fragment reference because that reference may not be valid when this saved state is later used. Likewise the Fragment's target and result code are not included in this state.
| Returns | |
|---|---|
@Nullable Fragment.SavedState |
The generated state. This will be null if there was no interesting state created by the fragment. |
setFragmentFactory
public void setFragmentFactory(@NonNull FragmentFactory fragmentFactory)
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 | |
|---|---|
@NonNull FragmentFactory fragmentFactory |
the factory to use to create new Fragment instances |
| See also | |
|---|---|
getFragmentFactory |
setFragmentResult
public final void setFragmentResult(@NonNull String requestKey, @NonNull Bundle result)
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.
setFragmentResultListener
public final void setFragmentResultListener(
@NonNull String requestKey,
@NonNull LifecycleOwner lifecycleOwner,
@NonNull FragmentResultListener listener
)
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 | |
|---|---|
@NonNull String requestKey |
requestKey used to identify the result |
@NonNull LifecycleOwner lifecycleOwner |
lifecycleOwner for handling the result |
@NonNull FragmentResultListener listener |
listener for result changes |
setStrictModePolicy
public void setStrictModePolicy(@Nullable FragmentStrictMode.Policy policy)
Sets the policy for what actions should be detected, as well as the penalty if such actions occur. The child FragmentManager of all Fragments in this FragmentManager will also use this policy if one is not explicitly set. Pass null to clear the policy.
| Parameters | |
|---|---|
@Nullable FragmentStrictMode.Policy policy |
the policy to put into place |
unregisterFragmentLifecycleCallbacks
public void unregisterFragmentLifecycleCallbacks(
@NonNull FragmentManager.FragmentLifecycleCallbacks cb
)
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 | |
|---|---|
@NonNull FragmentManager.FragmentLifecycleCallbacks cb |
Callbacks to unregister |
Extension functions
FragmentManagerKt.commit
public final void FragmentManagerKt.commit(
@NonNull FragmentManager receiver,
boolean allowStateLoss,
@ExtensionFunctionType @NonNull Function1<@NonNull FragmentTransaction, Unit> body
)
Run body in a FragmentTransaction which is automatically committed if it completes without exception.
The transaction will be completed by calling FragmentTransaction.commit unless allowStateLoss is set to true in which case FragmentTransaction.commitAllowingStateLoss will be used.
FragmentManagerKt.commitNow
@MainThread
public final void FragmentManagerKt.commitNow(
@NonNull FragmentManager receiver,
boolean allowStateLoss,
@ExtensionFunctionType @NonNull Function1<@NonNull FragmentTransaction, Unit> body
)
Run body in a FragmentTransaction which is automatically committed if it completes without exception.
The transaction will be completed by calling FragmentTransaction.commitNow unless allowStateLoss is set to true in which case FragmentTransaction.commitNowAllowingStateLoss will be used.
FragmentManagerKt.transaction
public final void FragmentManagerKt.transaction(
@NonNull FragmentManager receiver,
boolean now,
boolean allowStateLoss,
@ExtensionFunctionType @NonNull Function1<@NonNull FragmentTransaction, Unit> body
)
Run body in a FragmentTransaction which is automatically committed if it completes without exception.
One of four commit functions will be used based on the values of now and allowStateLoss:
| now | allowStateLoss | Method | | ----- | ---------------- | ------------------------------ | | false | false | commit() | | false | true | commitAllowingStateLoss() | | true | false | commitNow() | | true | true | commitNowAllowingStateLoss() |