A Fragment is a piece of an activity which enable more modular activity design. It will not be wrong if we say, a fragment is a kind of sub-activity.
If you want to create multi-UI pane than you should use fragment .
* A fragment has its own layout and its own behaviour with its own life cycle callbacks.
* You can add or remove fragments in an activity while the activity is running.
* You can combine multiple fragments in a single activity to build a multi-plane UI.
* A fragment can be used in multiple activities.
* Fragment life cycle is closely related to the life cycle of its host activity which means when the activity is paused, all the
fragments available in the activity will also be stopped.
* A fragment can implement a behaviour that has no user interface component.
* Fragments were added to the Android API in Honeycomb version of Android which API version 11.
If more space is available, multiple panels can be shown for Example:-
Here is the list of methods which you can to override in your fragment class :-
onAttach()The fragment instance is associated with an activity instance.The fragment and the activity is not fully initialized.
Typically you get in this method a reference to the activity which uses the fragment for further initialization work.
onCreate() The system calls this method when creating the fragment. You should initialize essential components of the fragment that you
want to retain when the fragment is paused or stopped, then resumed.
onCreateView() The system calls this callback when it’s time for the fragment to draw its user interface for the first time. To draw a UI
for your fragment, you must return a View component from this method that is the root of your fragment’s layout.
onActivityCreated()The onActivityCreated() is called after the onCreateView() method when the host activity is created. Activity and
fragment instance have been created as well as the view hierarchy of the activity.
onStart()The onStart() method is called once the fragment gets visible.
onResume()Fragment becomes active.
onPause() The system calls this method as the first indication that the user is leaving the fragment.
onStop()Fragment going to be stopped by calling onStop()
onDestroyView()Fragment view will destroy after call this method
onDestroy() called to do final clean up of the fragment’s state but Not guaranteed to be called by the Android platform.