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Introduction of Android?
Android is a mobile operating system based on Linux kernel. Android Operating System is developed by a team of Andy Roubine in Callifornia, Palo aloto city at 2003.Andy Roubine's team members are Rich Miner, Chris white and Nick Sears. Android operating system is open source operating system. Anybody can modify android operating system. Android operating system is the most popular operating system at this time. Approx 82% people uses android operating system. Android operating system provides a lot of features of customization. In 2005 Google acquires android. In 2007, Google announced that android is a mobile operating system. In 2008, HTC mobile company launched a mobile based on android operating system. That was first android mobile. It works on android version Cupcake. Here some android versions are given below:-
Name
|
Version
|
Launch Date
|
Security Patches
|
Alpha
|
1.0
|
Sep 23, 2008
|
Unsupported
|
Beta
|
1.1
|
Feb 09, 2009
|
Unsupported
|
Cupcake
|
1.5
|
April 27, 2009
|
Unsupported
|
Donut
|
1.6
|
Sep 05, 2009
|
Unsupported
|
Éclair
|
2.0-2.1
|
Oct 26, 2009
|
Unsupported
|
Froyo
|
2.3-2.3.7
|
May 20, 2010
|
Unsupported
|
Honeycomb
|
3.0-3.2.6
|
Feb 22, 2011
|
Unsupported
|
Ice cream sandwich
|
4.0-4.0.4
|
Oct 18, 2011
|
Unsupported
|
Jellybean
|
4.1-4.3.1
|
July 9, 2012
|
Unsupported
|
KitKat
|
4.4-4.4.4
|
Oct 31, 2013
|
Supported
|
Lollipop
|
5.0-5.1.1
|
Nov 12, 2014
|
Supported
|
Marshmallow
|
6.0-6.0.1
|
Oct 5, 2015
|
Supported
|
Nougat
|
7.0-7.1.2
|
Aug 22, 2016
|
Supported
|
Oreo
|
8.0
|
Aug 21, 2017
|
Supported
|
How a android program executes?
As a java program executes by JVM (java virtual machine). So a android program executes by DVM (Dalvik Virtual Machine).
DVM:- JAVAC tool compiles the java source code into .class file. The dex compiler converts all the class files into the .dex file that run on the Dalvik Virtual Machine. Multiple class files are converted into one dex file. The android asset packaging tool (aapt) handles the packaging process and generate a apk file.
Basic Components of Android Project:-
Activity:- An activity is a class that represents a single screen. It is like a frame in AWT.
View:- A view is a user interface element such as button, label, text field etc. Anything that you see is a view.
Intent:- Intent is used to invoke components. It is manly used to-
- · Start service
- · Launch an activity
- · Display a webpage
- · Display a list of component
- · Broadcast a message
- · Dial a phone call etc
Services:- Service is a background process that can run for a long time. There are two types of services local and remote. Local services is accessed from within the applications.
Content Provider:- Content providers are used to share data between the applications.
Fragment:- Fragments are like parts of activity. An activity can display one or more fragments on the screen at the same time.
Android Manifest.xml:- It contains information about activities, content providers, permissions etc. It is like the web.xml file in JAVA Enterprises Edition.
Android Virtual Device (AVD):- Android virtual device is used to test android application without the need for mobile or tablet etc. It can be created in different configuration to emulate different type of devices.
Career in Android:-
As we know that android is a fastest growing mobile operating system. It is a product of Google. As 2016 android is covering 87.8% market share. 2.6 million apps in Google play store. Android has 1.4 billion android users. 1.5 million android activations every day. According to US dollar android developer salary is $49,000 to $121,000 per year. And it increases 6% every year according to your work and experiences. Android Developer in Asian country might have less salary compared to US salary but yet very good compared to other job in Asian counties. Android is a open source operating system so you can learn android development free from various online sources. Android has official and powerful development framework that is known as android studio.
So we can say that android has a great career opportunity. Every company or organization wants to build a android app for their official use. They wants to maintain it in a right way and give updates to their clients. So android is a very good medium for them. They wants a android developer for build and maintain their app. So if you are interested to learn android development, must learn it.
How can you learn Android development?