Introduction to Android
B.Bhuvaneswaran
Assistant Professor (SS)
Department of Computer Science & Engineering
Rajalakshmi Engineering College
Thandalam
Chennai 602 105
bhuvaneswaran@rajalakshmi.edu.in
Contents
Introduction
Android version and API Level
The Big picture
Comparison of DVM and JVM
Android Features
Application Fundamentals
Android Application Components
B.Bhuvaneswaran, AP (SS) / CSE / REC
Introduction
A Linux based Operating System designed
primarily for touch screen mobile devices.
Initially developed by Android Inc and
later purchased by Google in 2005.
The first Android powered device was sold
in Oct 2008.
Android is Open Source and Google
releases code under Apache2 license.
Google Play Store.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Open Android.
What it means to be open and why would
you care?
http://www.apache.org/licenses/LICENSE-2.0.html
B.Bhuvaneswaran, AP (SS) / CSE / REC
Brief History Android
2009
SDK 1.5 (Cupcake)
SDK 1.6 (Donut)
Support Wide VGA
SDK 2.0/2.0.1/2.1 (Eclair)
New soft keyboard with autocomplete feature
Revamped UI, browser
2010
SDK 2.2 (Froyo)
Flash support, tethering
SDK 2.3 (Gingerbread)
UI update, system-wide copy-paste
B.Bhuvaneswaran, AP (SS) / CSE / REC
2011
SDK 3.0/3.1/3.2 (Honeycomb) for tablets only
SDK 4.0/4.0.1/4.0.2/4.0.3 (Ice Cream
Sandwich)
New UI for tablets, support multi-core processors
Changes to the UI, Voice input, NFC
2012
SDK 4.1/4.1.1/4.2(Jelly Bean)
Performance optimization, refined UI
Honeycomb
Ice cream Sandwich
Android 3.0-3.2
Android 4.0+
B.Bhuvaneswaran, AP (SS) / CSE / REC
Jelly Bean 4.1+
API Level
Platform Version
API Level
Version Name
Android 4.2
17
Jelly bean
Android 4.1, 4.1.1
16
Jelly bean
Android 4.0.3,
4.0.4
Android 4.0, 4.0.1,
4.0.2
Android 3.2
15
13
Ice cream
sandwich
Ice cream
sandwich
Honey Comb
Android 3.1.x
12
Honey Comb
Android 3.0.x
11
Honey Comb
Android 2.3.4
Android 2.3.3
10
Gingerbread
14
B.Bhuvaneswaran, AP (SS) / CSE / REC
API Level
Platform
Version
Android 2.3.2
Android 2.3.1
Android 2.3
Android 2.2.x
API Level
Version Name
Gingerbread
Froyo
Android 2.1.x
Eclair
Android 2.0.1
Eclair
Android 2.0
Eclair
Android 1.6
Donut
Android 1.5
B.Bhuvaneswaran, AP (SS) / CSE / REC
Cupcake
API Level
Android API levels can be divided to three
main groups:
Android 1.5 - 2.3 (API levels 3-10) - Android
made specifically for smartphones.
Android 3.0 - 3.2 (API levels 11-13) Honeycomb, Android made for tablets.
Android 4 (API levels 14-) - Ice Cream
Sandwich - Current generation, a big merge
with tons of additional functionality, totally
revamped Android version, for both phone and
tablets.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Choosing API Level
Depends Device support
Application forward compatibility
Application backward compatibility
B.Bhuvaneswaran, AP (SS) / CSE / REC
The Big Picture
B.Bhuvaneswaran, AP (SS) / CSE / REC
The Red Layer-The Linux Kernel
Android runs on Linux.
Linux provides hardware abstraction layer.
Users never see Linux sub system.
The adb command shell opens Linux shell.
B.Bhuvaneswaran, AP (SS) / CSE / REC
The Green LayerNative Libraries and Android Runtime
Pieces borrowed from other open source
projects:
Webkit for fast HTML rendering
OpenGL for graphics
Media codecs
SQLite database
Dalvik Virtual Machine
B.Bhuvaneswaran, AP (SS) / CSE / REC
The Blue LayerApplication Framework & Applications
B.Bhuvaneswaran, AP (SS) / CSE / REC
Activity BackStack
Main activity calls activity2
backstack
main
Push
Operation
(Last in)
Activity 2
B.Bhuvaneswaran, AP (SS) / CSE / REC
Activity 2 is
visible on
screen
Main activity
goes in
background
Activity BackStack
From activity2, user presses back button
backstack
main
Pop
operation
(First Out)
Activity 2
B.Bhuvaneswaran, AP (SS) / CSE / REC
Main activity is
visible on
screen and
activity 2 is
destroyed
Java Source Code
Java Source
Code
Java
Compiler
Java
Compiler
Java Byte Code
Dex
Compiler
Java Byte
Code
Dalvik Byte Code
Java Byte Code
Dalvik Executable
JVM
DVM
B.Bhuvaneswaran, AP (SS) / CSE / REC
Differences between DVM and JVM
Machine
DVM
JVM
Architecture
base
Register
Stack
No of operations
fewer
more
File format
.dex
.class
Property
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Stack Based
POP 20
POP 7
ADD 20, 7, result
PUSH result
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Register Based
Add R3,R1,R2
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Android Java Consists of
Android Java
=
Java SE - AWT/Swing
+
Android API
B.Bhuvaneswaran, AP (SS) / CSE / REC
Android Features
Application framework enabling reuse
and replacement of components.
Dalvik Virtual Machine optimized for
mobile devices.
Optimized graphics powered by a
custom 2D graphics library; 3D graphics
based on the OpenGL ES 1.0 specification
(hardware acceleration optional).
SQLite for structured data storage.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Media support for common audio, video, and still
image formats (MPEG4, H.264, MP3, AAC, AMR,
JPG, PNG, GIF).
GSM Telephony
Bluetooth, 3G, and Wi-Fi , Wi-Fi Direct, Wi-Fi
hotspot
(hardware dependent)
(hardware dependent)
Camera, GPS, compass, and accelerometer
(hardware dependent)
B.Bhuvaneswaran, AP (SS) / CSE / REC
Application Fundamentals
APK file format:
Application package file
Zip package format based on JAR file format
Apk holds
Code(.dex file)
Resources
Assets
Certificates
Manifest file
B.Bhuvaneswaran, AP (SS) / CSE / REC
Once .apk is installed on a device:
Own security sandbox
A unique Linux UserID
Own Virtual Machine
Own Linux process
B.Bhuvaneswaran, AP (SS) / CSE / REC
Android Application Components
Activities
Services
Content Providers
Broadcast Receivers
B.Bhuvaneswaran, AP (SS) / CSE / REC
Activity
An Activity is an application component
that provides a screen with which users
can interact in order to do something.
An activity is implemented as Subclass of
Activity.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Services
A Service is an application component that
can perform long-running operations in
the background and does not provide a
user interface.
A service is implemented as a subclass of
Service.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Content Providers
A content provider manages a shared set
of application data.
A content provider is implemented as a
subclass of ContentProvider.
B.Bhuvaneswaran, AP (SS) / CSE / REC
Broadcast Receivers
A broadcast receiver is a component that
responds to system-wide broadcast
announcements.
A broadcast receiver is implemented as a
subclass of BroadcastReceiver.
B.Bhuvaneswaran, AP (SS) / CSE / REC
B.Bhuvaneswaran, AP (SS) / CSE / REC
Summary
Android
Android
DVM Vs
Android
Android
Version and API
architecture
JVM
features
building blocks
B.Bhuvaneswaran, AP (SS) / CSE / REC
References
(1)http://developer.android.com/about/versions/index.html
(2)http://developer.android/reference/android/app/Activity.html
B.Bhuvaneswaran, AP (SS) / CSE / REC
B.Bhuvaneswaran, AP (SS) / CSE / REC
B.Bhuvaneswaran, AP (SS) / CSE / REC
