android introduction

Android

ByDurai. S

duraisy2k@gmail.com

Android

Android is a software platform for mobile devices based on the Linux Operating system an which is developed by Google and Open Handset Alliance.

Android is a software stack for mobile devices that includes an operating system and applications.

Open handset alliance

History of android

It was Founded in Palo Alto, California , United States in October 2003 by Andy Rubin , Rich Miner, Nick Sears and Chris White.

Google Inc. purchased the initial developer of the software , Android Inc in 2005.

Versions of android

Android 1.0

Android 1.1

Android 1.5 Cupcake.

Android 1.5 Donut.

Android 2.0/2.1 Éclair.

Android 2.2.x Froyo

Android 2.3.x Gingerbread

Android 3.x Honeycomb

Android 4.0.x Ice Cream Sandwich

Android 4.1.x Jelly Bean

Android Vs other mobile os

Comparison with ios

Comparison with symbian

ANDROID SYMBIAN

Easy to upgrade Upgrade is not available

Processor is high Processor speed is low

Lot of free apps in Google play

Less no of free apps in OVI store

Smooth handling Rough handling

User friendly Not User Friendly

Comparison with windows

ANDROID WINDOWS MOBILE

Android is Open source Platform

Windows mobile is similar to windows and has lot of legal bindings

Google Play has more than 500,000 apps

Compare with android it has only less no of apps and also no free apps

With Google it is more powerful with Google Maps and Google voice search

No such features are here

Google Wallet app No such type of app is there

Full , Multiple Account Sync ,no outlook required

Gmail support only through outlook express.

Building and Running

● Android asset packaging tool (aapt) crawls through the resource folder and generates an integer ID for every resource. These ID’s are written into R.java source file under generated sources folder where they can be accessed from application code.

● Java compiler (javac) compiles the application’s java source files along with generated source files

● Dexer (dx) translates the compiled Java bytecode into Dalvik bytecode (dex) format

● Apkbuilder zips the resource table, application code and compiled resource into an apk file

Building and Running

● Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single .apk file on the device. .dex files can be created by automatically translating compiled applications written in the Java programming language.

DVM vs JVM

Building Blocks of Android

● An Activity● An Intent● A Service● A Content provider● A Broadcast Receiver

An Activity

● The activity is the most visible form of an Android application. An activity presents the UI to an application, along with the assistance of a class known as a view

● An application may contain one or more activities. They are typically on a one-to-one relationship with the screens found in an application.

An intent

● An application moves from one activity to another by calling a method known as Intent.

A Service

● applications running "in the background"● The service is an Android application that has no UI

A Content Provider

A Broadcast receiver

● A Component that does nothing but receive and react to broadcast announcements.

● Doesn't has the UI.● They may start an Activity in response to the

information theu receive.

Life-Cycle of Activity

Life-Cycle of Activity

● onCreate():

Called when the activity is first created

An activity does all its initial setup of global state

Always followed by onStart()

Life-Cycle of Activity

● onRestart()

called after the activity has been stopped.

Always followed by onStart()

Life-Cycle of Activity

● onStart():

Called just before the activities become visible to the user

Followed by onResume() if the activity comes to the foreground

Life-Cycle of Activity

● onResume()

Called just before the activity starts interacting with the user

always followed by onPause()

Life-Cycle of Activity

● onPause():

Called when the system is about to start resuming another activity

The next Activity will not resumed until it returns.

Followed either by onResume() if the activity returns back to the front, or by onStop if it comes invisible to user.

Life-Cycle of Activity

● onStop:

Called when the Activity is no longer visible to user.

Because it is being destroyed or another activity has been resumed.

Followed either by onRestart() if the activity is coming back to interact with the user, or by onDestroy() if this activity is going away.

Life-Cycle of Activity

● onDestroy():

Called before the activity is destroyed

Final call that the activity will receive