Fragments

Question 1

Fragment

Answer 1

A reusable UI component with its own lifecycle

Question 2

Benefits of using fragments

Answer 2

Reuse a Fragment in more than on Activity
Add or remove dynamically as needed
Integrate a mini-UI within an Activity
Retain data instances after a configuration change
Represent sections of a layout for different screen sizes

Question 3

Steps to use a fragment

Answer 3

Create a subclass of Fragment
Create a layout for the Fragment
Add Fragment to a host Activity
         Statically in layout
         Dynamically using fragment transactions

Question 4

Examples of subclases of Fragment

Answer 4

DialogFragment: Floating dialog (examples: date and time pickers)
ListFragment: List of items managed by adapter
PreferenceFragment: Hierarchy of Preference objects (useful for Settings)

Question 5

Add a Fragment to an Activity

Answer 5

Add statically in Activity layout, visible for entire Activity lifecycle
Add (or remove) dynamically as needed during Activity lifecycle using Fragment transactions

Question 6

Add a Fragment dynamically

Answer 6

Specify ViewGroup for Fragment in layout
Instantiate the Fragment in Activity
Instantiate FragmentManager
      Use getSupportFragmentManager() for compatibility
Use Fragment transactions

Fragment operations are wrapped into a transaction:
Start transaction with beginTransaction()
Do all Fragment operations (add, remove, replace, hide, show, addtoBackStack() etc.)
End transaction with commit()

Question 7

Lifecycle

Answer 7

Lifecycle