Package icyllis.modernui.fragment

Class FragmentManager

java.lang.Object
icyllis.modernui.fragment.FragmentManager
All Implemented Interfaces:
FragmentResultOwner
public final class FragmentManager extends Object implements FragmentResultOwner
Interface for interacting with Fragment objects inside a host.

You should never instantiate a FragmentManager directly, but instead operate via the APIs on Fragment, or FragmentController to retrieve an instance.

For more information about using fragments, read the Android Fragments developer guide.

  • Field Details

    • POP_BACK_STACK_INCLUSIVE

      public static final int POP_BACK_STACK_INCLUSIVE
      Flag for popBackStack(String, int) and popBackStack(int, int): 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.
      See Also:

  • Method Details

    • beginTransaction

      @NonNull public 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 onSaveInstanceState() and prior to a following onStart or 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.

    • executePendingTransactions

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

    • 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.

    • popBackStackImmediate

      public boolean popBackStackImmediate()
      Like popBackStack(), but performs the operation immediately inside the call. This is like calling executePendingTransactions() afterwards without forcing the start of postponed Transactions.
      Returns:
      Returns true if there was something popped, else false.

    • 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:
      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 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 - Either 0 or POP_BACK_STACK_INCLUSIVE.

    • popBackStackImmediate

      public boolean popBackStackImmediate(@Nullable String name, int flags)
      Like popBackStack(String, int), but performs the operation immediately inside the call. This is like calling executePendingTransactions() afterwards without forcing the start of postponed Transactions.
      Returns:
      Returns true if there was something popped, else false.

    • 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:
      id - 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 - Either 0 or POP_BACK_STACK_INCLUSIVE.

    • popBackStackImmediate

      public boolean popBackStackImmediate(int id, int flags)
      Like popBackStack(int, int), but performs the operation immediately inside the call. This is like calling executePendingTransactions() afterwards without forcing the start of postponed Transactions.
      Returns:
      Returns true if there was something popped, else false.

    • getBackStackEntryCount

      public int getBackStackEntryCount()
      Return the number of entries currently in the back stack.

    • getBackStackEntryAt

      @NonNull public 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.

    • addOnBackStackChangedListener

      public void addOnBackStackChangedListener(@NonNull FragmentManager.OnBackStackChangedListener listener)
      Add a new listener for changes to the fragment back stack.

    • removeOnBackStackChangedListener

      public void removeOnBackStackChangedListener(@NonNull FragmentManager.OnBackStackChangedListener listener)
      Remove a listener that was previously added with addOnBackStackChangedListener(OnBackStackChangedListener).

    • setFragmentResult

      public void setFragmentResult(@NonNull String requestKey, @NonNull DataSet result)
      Description copied from interface: FragmentResultOwner
      Sets the given result for the requestKey. This result will be delivered to a FragmentResultListener that is called given to FragmentResultOwner.setFragmentResultListener(String, LifecycleOwner, FragmentResultListener) with the same requestKey. If no FragmentResultListener with the same key is set or the Lifecycle associated with the listener is not at least Lifecycle.State.STARTED, the result is stored until one becomes available, or FragmentResultOwner.clearFragmentResult(String) is called with the same requestKey.
      Specified by:
      setFragmentResult in interface FragmentResultOwner
      Parameters:
      requestKey - key used to identify the result
      result - the result to be passed to another fragment

    • clearFragmentResult

      public void clearFragmentResult(@NonNull String requestKey)
      Description copied from interface: FragmentResultOwner
      Clears the stored result for the given requestKey.

      This clears any result that was previously set via FragmentResultOwner.setFragmentResult(String, DataSet) that hasn't yet been delivered to a FragmentResultListener.

      Specified by:
      clearFragmentResult in interface FragmentResultOwner
      Parameters:
      requestKey - key used to identify the result

    • setFragmentResultListener

      public void setFragmentResultListener(@NonNull String requestKey, @NonNull LifecycleOwner lifecycleOwner, @NonNull FragmentResultListener listener)
      Description copied from interface: FragmentResultOwner
      Sets the FragmentResultListener for a given requestKey. Once the given LifecycleOwner is at least in the Lifecycle.State.STARTED state, any results set by FragmentResultOwner.setFragmentResult(String, DataSet) using the same requestKey will be delivered to the callback. The callback will remain active until the LifecycleOwner reaches the Lifecycle.State.DESTROYED state or FragmentResultOwner.clearFragmentResultListener(String) is called with the same requestKey.
      Specified by:
      setFragmentResultListener in interface FragmentResultOwner
      Parameters:
      requestKey - requestKey used to identify the result
      lifecycleOwner - lifecycleOwner for handling the result
      listener - listener for result changes

    • clearFragmentResultListener

      public void clearFragmentResultListener(@NonNull String requestKey)
      Description copied from interface: FragmentResultOwner
      Clears the stored FragmentResultListener for the given requestKey.

      This clears any FragmentResultListener that was previously set via FragmentResultOwner.setFragmentResultListener(String, LifecycleOwner, FragmentResultListener).

      Specified by:
      clearFragmentResultListener in interface FragmentResultOwner
      Parameters:
      requestKey - key used to identify the result

    • putFragment

      public void putFragment(@NonNull DataSet bundle, @NonNull String key, @NonNull Fragment fragment)
      Put a reference to a fragment in a DataSet. This DataSet can be persisted as saved state, and when later restoring getFragment(DataSet, String) will return the current instance of the same fragment.
      Parameters:
      bundle - The bundle in which to put the fragment reference.
      key - The name of the entry in the bundle.
      fragment - The Fragment whose reference is to be stored.

    • getFragment

      @Nullable public Fragment getFragment(@NonNull DataSet bundle, @NonNull String key)
      Retrieve the current Fragment instance for a reference previously placed with putFragment(DataSet, String, Fragment).
      Parameters:
      bundle - The bundle from which to retrieve the fragment reference.
      key - The name of the entry in the bundle.
      Returns:
      Returns the current Fragment instance that is associated with the given reference.

    • findFragment

      @NonNull public static <F extends Fragment> F 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 Fragment.onCreateView(icyllis.modernui.view.LayoutInflater, icyllis.modernui.view.ViewGroup, icyllis.modernui.util.DataSet) and its children.

      Type Parameters:
      F - the fragment type
      Parameters:
      view - the view to search from
      Returns:
      the locally scoped Fragment to the given view
      Throws:
      IllegalStateException - if the given view does not correspond with a Fragment.
      ClassCastException - if the given type parameter is wrong

    • getFragments

      @NonNull public 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.

      Returns:
      A (new) list of all fragments that are added to the FragmentManager.

    • isDestroyed

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

    • toString

      @NonNull public String toString()
      Overrides:
      toString in class Object

    • 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:
      prefix - Text to print at the front of each line.
      fd - The raw file descriptor that the dump is being sent to.
      writer - A PrintWriter to which the dump is to be set.
      args - Additional arguments to the dump request.

    • findFragmentById

      @Nullable public Fragment findFragmentById(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.
      Returns:
      The fragment if found or null otherwise.

    • findFragmentByTag

      @Nullable public 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.

      Parameters:
      tag - the tag used to search for the fragment
      Returns:
      The fragment if found or null otherwise.

    • 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 FragmentTransaction.commit() instead of FragmentTransaction.commitAllowingStateLoss() will change the state and will result in an error.
      Returns:
      true if this FragmentManager's state has already been saved by its host

    • getPrimaryNavigationFragment

      @Nullable public Fragment getPrimaryNavigationFragment()
      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:
      the fragment designated as the primary navigation 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:
      fragmentFactory - the factory to use to create new Fragment instances
      See Also:

    • getFragmentFactory

      @NonNull public FragmentFactory getFragmentFactory()
      Gets the current FragmentFactory used to instantiate new Fragment instances.

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

      Returns:
      the current FragmentFactory

    • registerFragmentLifecycleCallbacks

      public void registerFragmentLifecycleCallbacks(@NonNull 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:
      cb - Callbacks to register
      recursive - true to automatically register this callback for all child FragmentManagers

    • unregisterFragmentLifecycleCallbacks

      public void unregisterFragmentLifecycleCallbacks(@NonNull 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:
      cb - Callbacks to unregister

    • addFragmentOnAttachListener

      public void addFragmentOnAttachListener(@NonNull FragmentOnAttachListener listener)
      Add a FragmentOnAttachListener that should receive a call to FragmentOnAttachListener.onAttachFragment(FragmentManager, Fragment) when a new Fragment is attached to this FragmentManager.
      Parameters:
      listener - Listener to add

    • removeFragmentOnAttachListener

      public void removeFragmentOnAttachListener(@NonNull FragmentOnAttachListener listener)
      Remove a FragmentOnAttachListener that was previously added via addFragmentOnAttachListener(FragmentOnAttachListener). It will no longer get called when a new Fragment is attached.
      Parameters:
      listener - Listener to remove