This document provides an introduction to Android development. It discusses what Android is, the benefits of developing for Android, Android architecture and core building blocks. Android is an open source software stack that includes an operating system, middleware and key applications for mobile devices. It is developed by the Open Handset Alliance led by Google. The document outlines Android's architecture including its use of Linux kernel, Dalvik virtual machine and Java programming language. It also describes important Android concepts like activities, views, resources, intents and AndroidManifest.xml.

1. Introduction to Android
Development
Can Elmas
March 07, 2012

2. Who am I ?
• 2008 GSU graduate
• Software Development Team Leader at Pozitron
– http://www.pozitron.com
• Interest in mobile platforms
• Experience with mobile platforms such as Symbian
(Java ME), BlackBerry and Android
• Experience with server side development

3. Agenda
• What is Android?
• Why Android?
• Android Architecture
• Android Building Blocks
• Demo

4. What is Android ?

5. What is Android?
• Software stack for mobile devices including an
operating system, middleware , key applications
and rich set of APIs
• Project by Open Handset Alliance led by Google,
a consortium of 86 companies (Samsung,
Motorola, Sony, HTC, LG, Dell, Intel, Nvidia etc.)
• First Release in November 2007

6. What is Android?
• Based on Linux Kernel
• Security, Memory Management, Process Management,
Network Stack, Driver stack
• No, Android is not Linux (No native windowing system, no
glibc, no standard GNU/linux utilities)
• Linux Kernel enhancements (alarm, ashmem, power
management, low memory killer - no swap space)
• Robust and proven over time

7. What is Android?
• Applications written primarily in customized version of
Java
• No, android is not Java
– Uses Java language
– Implements part of the Java 5 SE specification
(Collections, generics support)
– Runs on Dalvik Virtual Machine instead of JVM
– Multiple VMs

8. What is Android?
• Free and open
– No need of any user id or account for SDK access
– Source at http://source.android.com
• Rich Developer Community
• Cheaper and more innovative Mobile Devices
• Extendable
– Players can add proprietary functionality to their products
– Companies can remove functionality if they choose

9. What is Android?
• Android Market, 450.000 apps as of February
2012
• 850.000 devices activated every day,
according to Google’s Andy Rubin

10. What is Android?
• Mulitasking
• Integrated browser based on WebKit Engine
• 3d Graphics based on the OpenGL Es
• SQLite
• Camera, GPS, compass and accelerometer

11. Why Android?

12. Why Android?
• Free SDK
– Available at http://developer.android.com
• Open Source
• All applications are equal
• Dalvik Virtual Machine
• Development on Windows, Linux or Mac OS
• Starting development easy and cheap

13. Why Android?
• Rich Development Environment
– Full Device Emulator
– Tools for debugging DDMS (Dalvik Debug Monitor Server)
– Memory and performance profiling
• Rich Documentation
• Very large community and target audience
• Open Market Place
– Instant publishing

14. Android Architecture

16. Android Architecture
• Relies on Linux kernel version 2.6 for core system services
• Every Android application runs on its own process, with its
own Dalvik Virtual Machine
• C/C++ libraries (Surface Manager , Media Libraries, SQLite
etc.)
• Native set of core applications including email client, SMS,
Calendar, maps, browser, contacts and others

17. Android Building Blocks

18. Vocabulary
• Activity
• Views
• Resources
• Intents
• Intent Filters
• AndroidManifest.xml

19. Activity
• What the user see on the screen
• An Android application with User Interface
consists of one or more Activities.

20. Activity

21. Activity

22. Activity
• Moving through screens is by starting new activities
• Managed as an activity stack
• LIFO (Last In First Out)
• Only one is visible
• Only one is active
• Activity Lifecycle

23. Source : http://developer.android.com

24. Activity States
• Active
– At the top of the stack
• Paused
– Lost focusbut still visible
– Can be killed by Low Memory Killer
• Stopped
– Not at the top of the stack
• Dropped
– Killed to reclaim its memory

25. Activity
• An empty activity with no content

26. Views
• Views are basic UI building blocks
• They know how to draw themselves
– Android framework responsible for measuring, laying out and drawing
• Respond to events
• Implementation :
– Java code
– XML
– Separation of presentation of the application from the code controlling the
behavior.
– Ease of visualization of the UI structure
– Strings, color, styles, shapes, animations etc can be described as XML

27. Views
• Views and view groups trees build up
complex GUIs : widgets
– android.widget.ListView
– android.widget.TextView
– android.widget.Button
– android.widget.ImageView

28. Views
• Subclasses of ViewGroup, Layouts
• Standard layouts :
– LinearLayout
– FrameLayout
– TableLayout
– RelativeLayout
– AbsoluteLayout

29. Views
• Android UI in XML : /res/layout/main_act.xml

30. Resources
• External sources other than your code
(images, views and layouts in xml, strings
etc.) should be externalized, so that you can
maintain them independently

31. Resources
• Accessing application resources :
– R class
• All reources IDs are defined in R class, which is
automatically generated by Android aapt tool

32. Activity
• An empty activity with no content

33. Activity

34. Activity

35. Intents
• An Intention to do something
• Abstract description of an operation to be performed
• A message to the OS that you want to do something
(pre-defined action)
• Used to move from one Activity to another

36. Intents
• Facilitates app to app communication
• Primary Attributes
– Action
• The general action to be performed
– Data
• The data to operate on (a contact, an url, the new activity
etc.)

37. Intent Filters
• Description of what intent an activity is
capable of handling

38. Intent Filters

39. AndroidManifest .xml
• Description of the android application including
activities, intent receivers, permissions, application
icon, application name, version information etc.
• It’s the glue that specifies which Intents your activities
might receive
• An activity should be declared as the main entry point

40. AndroidManifest.xml

41. More Advanced Topics
• How Android deal with Fragmentation?
– API Levels (Cupcake, Donut, Eclair, Froyo,
Gingerbread, Honeycomb, Ice Cream Sandwich)
• How are the resources selected at run time
according to different screen sizes and
densities?

42. More Advanced Topics
• Single Threaded UI Model
• APK (Android Package)
• Application Signing

43. Thank you
• We’re Hiring
– http://pozitron.com/careers.php
– ik@pozitron.com
• Twitter
– @foragoodpurpose
– @Pozitron_Mobile

44. Demo
• Phase 1:
– Create a new Android project with package name
com.gsuandroid.activities
– Create a new Activity called MainActivity
– Create a layout for MainActivity which will consist
of a LinearLayout containing a TextView with
predefined text “Hello Android”
– Run your application

45. Demo
• Phase 2:
– Create another activity called ActTwo
– Create a layout for your new activity containing a TextView
without setting a text in XML
– Modify your MainActivity’s layout xml in and add a Button with
setting and id, android:id="@+id/btn_go_to_act_two » and text
« Go to Next Activity»
– Start ActTwo when user presses button inserted in the
MainActivity
– Run your application

46. Demo
• Phase 3:
– Pass a text message “That’s it for today” when
moving from MainActivity to ActTwo
– Run your application

47. Full Code

49. main_act.xml

50. act_two.xml