Android is the most popular mobile operating system with over 1 billion users worldwide. It was developed by Android Inc, which was acquired by Google in 2005. Android is an open source platform that runs on many device types beyond just phones, with the goal of a unified platform across all mobile devices. It uses Linux at its core, and includes components like activities, intents, services, and broadcast receivers to define its application framework.

1. ANDROID OVERVIEW
Android is the most
popular mobile
operarting system in
the world with a User
Base of precisely 1
Billion and growing at
the rate of 1 million
new activations every
day.

2. HISTORY AND POSSIBLE FUTURE
2005
Google buy Android Inc.
Work on Dalvik starts
2007
Open Handset Alliance Announced
Early SDK Releases
2008 - 10
Android becomes dominant
mobile platform
Games, Tablets, Tvs, Sunglasses
etc
Beyond Phones
2011 - 13
Future ?

3. VISION OF ANDROID
Our goal is not just a single
device. Our vision is a mobile
platform that runs on many
many different devices.
– Eric Schmidt

4. PLATFORM VERSIONS
Version
API Level
Nickname
Android 1.0
1
Android
Android 1.1
2
Android
Android 1.5
3
Cupcake
Android 1.6
4
Donut
Android 2.0
5
Eclair
Android 2.01
6
Eclair
Android 2.1
7
Eclair
Android 2.2
8
Froyo
Android 2.3
9
Gingerbread
Android 2.3.3
10
Gingerbread
Android 3.x
11, 12, 13
Honeycomb
Android 4.0
14, 15
Ice Cream Sandwich
Android 4.1.x; 4.2.x; 4.3.x
16, 17, 18
Jelly Bean
Android 4.4
19
KitKat

5. VERSION DISTRIBUTION

6. ADD-ONs

7. “WITH GOOGLE”
Devices that have “with Google” add-on feature a set of Google’s proprietary
applications, such as Maps, Gmail, Gtalk, and many others.
OEMs and carriers typically enter into a licensing agreement with Google in
order to distribute Google version of Android.

8. ANDROID STACK

9. THE STACK

10. LINUX KERNEL
Android runs on Linux.
Linux provides:
Hardware abstraction layer
Memory management
Process management
Networking
Users never see Linux sub system
The adb shell command opens
Linux shell

11. NATIVE LIBRARIES
Pieces borrowed from other
open source projects:
Bionic, a super fast and small
license-friendly libc library
optimized for Android
WebKit library for fast HTML
Rendering
OpenGL for graphics
Media codecs offer support for
major audio/video codecs
SQLite database
Much more...

12. DALVIK
Dalvik VM is Android
implementation of Java VM
Dalvik is optimized for mobile
devices:
• Battery consumption
• CPU capabilities
Key Dalvik differences:
• Dalvik runs .dex files
• More efficient and compact
implementation
• Different set of Java libraries
than JDK

13. APPLICATION FRAMEWORK
The rich set of system
services wrapped in an
intuitive Java API.
This ecosystem that
developers can easily tap into
is what makes writing apps
for Android easy.
Location, web, telephony,
WiFi, Bluetooth,
notifications, media, camera,
just to name a few.

14. Dalvik Executable + Resources = APK
Must be signed (but debug key is okay
for development)
Many markets with different policies

15. MAIN BUILDING BLOCKS

16. ACTIVITY AND IT'S LIFECYCLE
An Activity
Represents a screen
or a window
Activities have a
well - defined
lifecycle.
The
Android OS
manages
your activity by
changing its state.

17. INTENTS
Intents represent
events or actions.
They are to
Android apps what
hyperlinks are to
websites. Sort of.
Intents can be
implicit or explicit.

18. SERVICES AND IT'S LIFECYCLE
Services are code that runs
in the background. They
can be started and
stopped. Services doesn’t
have
UI.
Service also has a
lifecycle, but it’s much
simpler than activity’s.

19. BROADCAST RECEIVERS
An Intent-based publish-subscribe mechanism.
Great for listening system events such as SMS messages.

20. ADAPTERS
To make sure they run smoothly, Android uses Adapters to connect
them to their data sources.
A typical data source is an Array or a Database

21. TWO UI APPROACHES
You can mix and match both styles. Best practice:
Start with XML and declare most of UI
Switch to Java and implement the UI logic

22. SANDBOXING
No app can adversely impact other apps,
user, or OS
Cannot read/write user’s private data
Cannot read other app’s data
Cannot perform network access
Cannot keep device awake, and so on
Each application is its own sandbox
To share resources, apps need to request
permissions, User must grant permissions at
install time
An application is an island on its own.
It contains any number of Activities,
Services, Receivers and Providers.
It has its own file system, database,
place to store native libraries.