The document introduces the Android operating system. It was created by Google and the Open Handset Alliance to provide an open-source alternative to Apple's iOS and compete in the growing smartphone market. Android uses the Linux kernel and a customized virtual machine called Dalvik to deliver the benefits of Java programming on mobile devices without the performance disadvantages of traditional Java VMs. The architecture is based around activities representing screens, views for building user interfaces, and intents for messaging and navigation between components.

1. Introducing Android
Cory Maksymchuk
cory.maksymchuk@protegra.com
cory.maksymchuk@gmail.com

8. Today
• Java is dead?
• What is Android and why was it made?
• Open?
• Money?
• Overview of android architecture
• Sample Application

9. Java is Dead

10. Android
Worldwide Smart Phone Market share
• 2009 – 3.9%
• 2010 – 23%
• 2011 – 38%
• 2012 – 49%
• 3 years = 500 million smart phones running Android

11. Why Java?
• Mature Language
• Massive open source community
• Excellent tools/IDEs
• Large, slow bloated Virtual Machine
- Dalvik = Small, fast optimized Virtual Machine
• All benefits, no disadvantages
- Except?

12. What is Android?
How was growth achieved?
• Operating system, built on Linux
• Compiler, debugger, emulator, VM
• Open sourced code under Apache 2 license
• Open Handset Alliance – 84’ish Companies
- Why?
- Open standards to allow it to grow
- Ability to compete – Apple, Symbian/Nokia, RIM, Microsoft
- Google = Smart
• Android vs. iPhone?

13. Open?
• Yes… but No…
• Open
- A license that insures the code can be modified, reused and
distributed
- A community development approach
- Assurance the users have total freedom over the device and
software.
• Google has achieved ½ of openness – Legally Open
Source
• Is their ‘community development approach’ any different
than Apple or RIM?

14. Money?
• What kind of a company is Google?
• How do they make money?
• Android simply makes them better at doing what they’ve
always done best.

16. 3 Things
• Activities = Screens
• Views/Widgets = Components
• Intents = Messages - used for navigation (among other
things)

17. Activities = Screens
• Screens have lifecycles on Mobile devices
- onCreate() — Activity is first created
- onStart() — Becomes visible
- onResume() — Interacting with the user
- onPause() — Current activity-> another activity resumed
- onStop() — No longer visible to the user
- onDestroy() — Before the activity is destroyed
- onRestart() — Restarting again

19. Views
• Basic building block for UI components
Layout
Widget ViewGroup
View

20. Views – Cont’d
• To add views to a screen/activity, create hierarchy of
views, then call setViewGroup(…) in the activity.
• Layout may contain layout and buttons, text fields, radio
buttons, etc.

21. Intents = Messages
• Main communication mechanism in Android
1) Used to call other apps or screens – This is us!
2) Send a message to someone who is listening
- Low battery
- Time zone change
3) Start a service
- Download a file
- Start/Check the status of a process

22. Intents/Messages
What do they contain?
• Component name – Unique identifier of component
- This is an explicit intent
• Activity
- ACTION_CALL
- ACTION_EDIT
- ACTION_SYNC
- ACTION_VIEW
• Data
- URI and MIME type (http://www.protegra.com)
• Category
- Logical Grouping of activities
• Extras
- Key/Value pairs

23. Intent Filters – Intent Resolution
• Data
• <intent-filter . . . >
<action android:name="com.example.project.SHOW_CURRENT" />
<action android:name="com.example.project.SHOW_RECENT" />
...
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.BROWSABLE" />
...
<data android:mimeType="video/mpeg" android:scheme="http" . . . />
<data android:mimeType="audio/mpeg" android:scheme="http" . . . />
</intent-filter>

24. Summary
• Screens = Activities
• Screens have components (Views) to manage layouts
as well as widgets, etc.
• Activities call other Activities, invoke services and send
messages using Intents

25. Code