A wrapper for Fragment Manager that streamlines some common operations over Fragments

Project maintained by Sefford Hosted on GitHub Pages — Theme by mattgraham


A wrapper to Android Fragment Manager to encapsulate common operations concerning the fragment lifecycles.


The idea of Fraggle is to reduce the boilerplate of having the managing code of the Fragment handling inside your Activity and reduce and encapsulate it away; providing it as a kind of service inside it.

This allows to abstract your application's flow behavior from the actual management of it.



Fraggle comes bundled in aar format. Grab the latest bundle from here




compile 'com.sefford:fraggle:1.2.1@aar'


Hooking Fraggle to your Activities

Fraggle can be used standalone or through a dependency injection framework as Dagger or Guice. However in order to use it you will need to manually inject the FragmentManager using the init(FragmentManager fragment) method, as a FragmentManager instance will not be available until you have created the Activity.

Currently this version of Fraggle only supports Android's native FragmentManager (API 14 onwards).

Until I do a support version, forking and using SupportFragmentManager is as simple as substituting the instance for a Support Fragment Manager. Sorry about that.

Hooking Fraggle to your Fragments

Fraggle has an interface FraggleFragment to extend your Fragments with certain functionalities.

The first one is to enforce the Fragment to self-identify through the getFragmentTag method. This method is intended to provide the runtime identification for both logging purposes and as way for Fraggle to look up Fragments in the backstack.

Another functionality available to FraggleFragments is to decide if there are customized behaviors for clicking the Back Button using hasCustomizedBackAction() and onBackPressed() methods. The first is used to identify if the FraggleFragment itself has a customized action for clicking the back button, and the second to actually execute it.

The conditions will be only evaluated on the moment the user clicks on the back button, so the behavior can be dynamically updated depending on certain conditions of the view.

Additionally the FraggleFragment can signal the FraggleManager to make a jump of several Fragments in the backstack providing such Fragments exist, by looking up the backstack for a certain Fragment tag. In order to activate this functionality the FraggleFragment must override onBackPressedTarget() method with a known tag. This can be used to perform hierarchical navigation or returning from long processes or error states to past Fragments. As with the previous point, this behavior can be changed in runtime depending of the flow of the application.

There is another addition in order to prevent endless cycles of navigation through your flow. This is isSingleInstance() method. It will signal the FraggleManager that before adding a new instance it should try to find and pop an existing instance of such Fragment.

In Fraggle there is a concept known in Fraggle as Entry Fragment. An Entry Fragment is a Fragment such as popping back from the back stack should signal your activity to finish(). This is achieved by letting Fragments override isEntryFragment() method.

FraggleFragment interface extends the Fragment lifecycle with onFragmentVisible() and onFragmentNotVisible() methods for certain situations.

Instantiating new Fragments

The FraggleManager API is simple. In order to instantiate a new Fragment addFragment() should be called. This takes five parameters:

The FraggleManager will configure properly the Fragment and perform the transaction.

The available flags for configuring a Fragment are:

Popping back Fragments

Before popping back a Fragment, Fraggle will check out some conditions about the Fragment on top of the backstack.

  1. Know if the Fragment has a customized code that the Fragment must execute, then execute it.
  2. If not, check if it has to perform a jump by reading the onBackPressedTarget() tag.
  3. Execute the correct jump whether is popping a single element from the back stack, or a particular element.

Bear in mind that performing a finish() in the activity is not the responsibility of the FraggleManager, and the developer should take care of the correct conditions for his Activity to correctly finish. However, the Activity can query the FraggleManager with peek() for the top Fragment and see if the isEntryFragment() method returns true.


You can find a sample project showcasing Fraggle capabilities at this url


Copyright 2014 Sefford.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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