Android Programming - Day One

Pradip Pandey
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In this article series, I will explain about various sections of Android Application Development. In day one, we will see the following points:

What is Android?
Android Versions.
Android Architecture
Different type of Android devices
Steps to get the tools and SDK for creating environment for Android application. Below picture says 'Who Am I ?'

1. 1. What is Android?

Android is a mobile operating system which is based on a modified version of Linux. It was first developed by a startup company with name Android Inc. In 2005, Google purchased it and took over its development work.

2. 2. Android Versions

Following table shows a brief history of Android Versions which are based on different type of fruit names along with release date.

Version	Release Date	CodeName
1.1	9^th Feb 2009
1.5	30^th April 2009	Cupcake
1.6	15^th Sep 2009	Donut
2.0 and 2.1	26^th Oct 2009	Éclair
2.2	20^th May 2010	Froyo
2.3	6^th Dec 2010	Gingerbread
3.0, 3.1, 3.2	22^nd Feb 2011	Honeycumb
4.0	19^th Oct 2011	Ice Cream Sandwich
4.1	9^th July 2012	Jelly Beans
4.4	31^st Oct 2013	Kitkat
5.0	12^th Nov 2014	Lollipop

3. Architecture

It is very important to know about the architecture of the Android operating system before start programming for Android application development.

The Android Operating System is roughly into five sections in four main layers.

3.1 Linux Kernel - Android is based on Linux Kernel. This layer contains all the low level device drivers for the various hardware components.
3.2 Libraries – It contains all the code that provides the main features of an Android OS. e.g Libraries of SQLite, WebKit etc.
3.3 Android Runtime- It provides a set of core libraries that enable developers to write Android apps using the Java Programming Language. It also includes the Dalvik virtual machine, which enables every Android application to run in its own process.
3.4 Application Framework- It exposes the various capabilities of the OS to application developers to use them in the applications.
3.5 Applications-Any applications that the developers write are located in this layer.

APPLICATIONS

HOME Contacts Phone Browser

APPLICATION FRAMEWORK

Activity Manager Window Manager Content Providers View System
Package Manager
Telephony Manager Resource Manager Location Manager`
Notification Manager

LIBRARIES ANDROID RUNTIME

Surface Manager Media Framework SQLite Open GL/ES Dalvik Virtual Machine
FreeType WebKit SGL SSL Core Libraries

LINUX KERNEL

Display Driver Camera Driver Flash Memory Driver Keypad Driver
Wi-Fi Driver Audio Drivers Power Management

4. Different types of Android devices

Various types of Android devices are in the market with different shapes and sizes.

4.1 Smartphones
4.2 Tablets
4.3 Netbooks
4.4 MP4 players
4.5 Internet TVs

5. Steps to get the tools and SDK for creating environment for Android application.

Android SDK is the most important software that is required to download because it contains a debugger, libraries, an emulator, documentation, sample code and many tutorials. So you can download it from http://developer.android.com/sdk/index.html .

When the file download is complete, install Android studio and necessary SDK tools as per Setup Wizard. Below picture shows that it is already installed in the system.

At the time of installation of Android Studio, it might give an error due to JDK is not installed in the system. To check which version of Java is installed, open a command line and type javac -version

If the JDK is not available or the version is lower than 1.8, download it from http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html,

When JDK download completes, install it and set a new system variable JAVA_HOME that point to the JDK installed folder .

e.g C:\Program Files\Java\jdk1.8.0_25

To create JAVA_HOME variable, select Start Menu->Computer->System Properties->Advanced System Properties. Open Advanced Tab->Environment Variables.

Thus we have created complete environment for Android programming.

Before starting programming, we will have to configure the Android SDK Manager. Open Android Studio from the desktop icon display in above image.

Click on SDK Manager icon to install SDK manager.

It manages the various versions of Android SDK which are currently installed on the system.

Each version of the Android OS is identified by an API level number. After installing above required APIs provided by Google (Google Map library), finally the environment is complete for Android programming.

Sources: Images for Smartphones