Andriod introduction

Android is a complete set of software for mobile devices such as tablet computers, notebooks, smartphones, electronic book readers, set-top boxes etc.

It contains a linux-based Operating System, middleware and key mobile applications.

It can be thought of as a mobile operating system. But it is not limited to mobile only. It is currently used in various devices such as mobiles, tablets, televisions etc.

What is Android
what is android
Before learning all topics of android, it is required to know what is android.

Android is a software package and linux based operating system for mobile devices such as tablet computers and smartphones.

It is developed by Google and later the OHA (Open Handset Alliance). Java language is mainly used to write the android code even though other languages can be used.

The goal of android project is to create a successful real-world product that improves the mobile experience for end users.

There are many code names of android such as Lollipop, Kitkat, Jelly Bean, Ice cream Sandwich, Froyo, Ecliar, Donut etc which is covered in next page.

What is Open Handset Alliance (OHA)
It's a consortium of 84 companies such as google, samsung, AKM, synaptics, KDDI, Garmin, Teleca, Ebay, Intel etc.

It was established on 5th November, 2007, led by Google. It is committed to advance open standards, provide services and deploy handsets using the Android Plateform.

History of Android
The history and versions of android are interesting to know. The code names of android ranges from A to J currently, such as Aestro, Blender, Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwich, Jelly Bean, KitKat and Lollipop. Let's understand the android history in a sequence.

1. Initially, Andy Rubin founded Android Incorporation in Palo Alto, California, United States in October, 2003.

2. In 17th August 2005, Google acquired android Incorporation. Since then, it is in the subsidiary of Google Incorporation.

3. The key employees of Android Incorporation are Andy Rubin, Rich Miner, Chris White and Nick Sears.

4. Originally intended for camera but shifted to smart phones later because of low market for camera only.

5. Android is the nick name of Andy Rubin given by coworkers because of his love to robots.

6. In 2007, Google announces the development of android OS.

7. In 2008, HTC launched the first android mobile.
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Android Architecture
android architecture or Android software stack is categorized into five parts:

linux kernel
native libraries (middleware),
Android Runtime
Application Framework
Applications
Let's see the android architecture first.

Android Core Building Blocks
android components
An android component is simply a piece of code that has a well defined life cycle e.g. Activity, Receiver, Service etc.

The core building blocks or fundamental components of android are activities, views, intents, services, content providers, fragments and AndroidManifest.xml.

Activity
An activity is a class that represents a single screen. It is like a Frame in AWT.

View
A view is the UI element such as button, label, text field etc. Anything that you see is a view.

Intent
Intent is used to invoke components. It is mainly used to:

Start the service
Launch an activity
Display a web page
Display a list of contacts
Broadcast a message
Dial a phone call etc.

Service
Service is a background process that can run for a long time.

There are two types of services local and remote. Local service is accessed from within the application whereas remote service is accessed remotely from other applications running on the same device.

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.

AndroidManifest.xml
It contains informations about activities, content providers, permissions etc. It is like the web.xml file in Java EE.

Android Virtual Device (AVD)
It is used to test the android application without the need for mobile or tablet etc. It can be created in different configurations to emulate different types of real devices.