android jam - loaders - udacity lesson 4c

Android ManchesterWeek 6 - Loaders

Overview

● Sponsors message - Novoda● Retro

○ Lesson 4c Loaders● Looking Forward

○ Lesson 5 Rich and Responsive layouts● Stickers + Booklets● Questionnaire● Next Tue 7-8pm SpacePortX

Energizer

Stand up and introduce yourself to somebody around you, you don’t know

Prime Directive

‘Regardless of where we are up to, we understand and truly believe that everyone did the best job he or she could, given his or her skills and abilities, the personal time available, and the situation at hand.’

Difficulty Check● Who completed the class?

● How long did it take?

● Hands up 1-10 difficulty of the weeks lesson

● Any specific areas of the lesson that require particular focus?

Retro lesson 4c Loaders

What we learnt last week● Problems ● Solution with loader● Key methods● How loaders fit into the bigger picture

Problems 1

Problem 2

● Loading data in UI/Main thread can take time and make UI less responsive○ Load data in AsyncTask why don’t we?

■ On orientation change we’ll re-create AsyncTask and consume even more resources

● Loaders registered to LoaderManager via static ID and live beyond lifecycle of Fragment or Activity○ Monitor source changes and deliver new data.

(Cursor)Loader 1● Available from HoneyComb (3.0+)

○ Available in compatibility library● Load data in AsyncTask on the background thread

○ provides updates to UI thread.● CursorLoader = AsynTaskLoader for content

providers○ Returns cursor to UI ○ Monitors changes to data and notifies UI○ On rotation when activity reconnects to loader

its passed the last Cursor

(Cursor)Loader 2

● Key components○ Loader_ID○ Interface to implement

■ LoaderManager.LoaderCallbacks<Cursor>

○ InitLoader■ getLoaderManager().initLoader(ID, null, this);

○ Callbacks■ public Loader<Cursor> onCreateLoader(int loaderID, Bundle bundle) //Build Uri and create new CursorLoader

■ public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) //update adapter with new cursor

■ public void onLoaderReset(Loader<Cursor> loader) // release resources

Without loaders

With Loaders

What went well

What went well

● Responsive○ Hard work off UI/Main thread

Data retrieval not tied to Activity lifecycleSaves resources/memory

● Makes observing data easier○ Less coding

● Updates update the UI without us doing anything!

What didn’t go so well

What didn’t go so well

● More coding○ Time consuming

● Loaders are crayzay! initLoader() vs restartLoader() ?!?

Q&APlease pleassssse... fill in sruvey http://goo.gl/JHulAu

Next Week - Android Jam

Rich Layouts (location: Store room)

Next Lesson - Rich Layouts

Learning Objectives:- Screen densities- Fragments- Orientation change - preserving data- 2 pane layout- ActionBar- Custom Views

See you next week..

- Time: Tuesday 7pm - Place: SpacePort- Things needed: You + Questions +

Feedback- Can contact us if issues:

@blundell_apps / @android_mcr

Go forth and discuss