EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E
Programming Mobile Applications for Android
Adam Porter, University of Maryland
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C O U R S E L E C T U R E The Fragment Class Notes taken on July 1, 2014 by Edward Tanguay |
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fragments were added to Android 3.0 to better support interfaces for devices with larger screens
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some of the design heuristics that made sense for smaller phone display no longer work
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example application: quote viewer
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two activities
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1. shows titles of Shakespeare plays
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2. when title is selected, a quote from that play is shown
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this is an appropriate interface for a phone
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on a tablet, however, the display is not too high and wide
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too much white space
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uses little of the vertical space
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imposes a slow back-and-forth user experience since the user has to move his hand so far
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better layout for tablet:
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quotes now get shown on right
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single activity
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two fragments
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fragments
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are hosted by activities
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an activity can host zero or more fragments
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lifecycle of a fragment is tied to the lifecycle of the activity that is hosting it
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a fragment is statically bound to its hosting activity
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a fragment also has some of its own lifecycle callbacks
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two states
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resumed
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fragment is visible in running activity
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paused
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another activity is in the foreground and has focus
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containing activity is visible
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stopped
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fragment is not visible
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lifecycle callback statements
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onAttach()•
fragment is first attached to activity
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onCreate() (not the same as the activity)•
unlike in activity.onCreate(), you don't set up the user interface here, but in onCreateView()
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onCreateView()•
set up user interface
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sets up and returns a view which contains the fragment's user interface
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onActivityCreated()•
fragment gets this call after its view has been installed in the activity's view hierarchy
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after fragment's user interface has been installed in the activity, its lifecycle is dependent on the life cycle of the activity
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if the hosting activity is about to become visible, it will receive a call to its
onStart() method, and the fragment will also receive a call to its onStart() method•
same with
onResume()•
same with
onPause()•
same with
onStop()•
when activity is destroyed, fragment receives a call to
onDestroyView()•
clean up resources associated with the view
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then when fragment is no longer in use, it receives a call to its
onDestroy() method•
when no longer attached to activity, it receives called to
onDetach() where you might want to null out references to the hosting activity