Android Interview Questions and Answers

The history and versions of android is very interesting. The codenames of android ranges from A to J currently, such as Aestro, Blender, Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwitch,Jelly Bean and KitKat. 

Let's understand the android history pointly:

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

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

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

Android software stack (also known as android architecture) includes linux kernal, native libraries (middleware), Android Runtime, Application Framework and Applications.

Linux Kernal is responsible for device drivers, power management, resource access etc. OS tasks.

On the top of linux kernal, their are Native libraries such as WebKit, OpenGL, FreeType, SQLite, Media, C runtime library (libc) etc.

The WebKit library is responsible for browser support, SQLite is for database, FreeType for font support, Media for playing and recording audio and video formats.

The main Android API's are UI (User Interface), telephony, resources, locations, Content Providers (data) and package managers.

A 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.

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

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

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 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 Providers are used to share data between the applications.

Fragments are like parts of activity. An activity can display one or more fragments on the screen at the same time.

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

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.

Android Emulator is used to run, debug and test the android application. If you don't have the real device, it can be the best way to run, debug and test the application.

It uses an open source processor emulator technology called QEMU.

The emulator tool enables you to start the emulator from the command line. You need to write:

In case of Eclipse IDE, you can create AVD by Window menu > AVD Manager > New.

Android supports java, c++, c# etc. language to develop android applications. Java is the officially supported language for android. All the android examples of this site is developed using Java language and Eclipse IDE.

Here, we are going to tell you, the required softwares to develop android applications using Eclipse IDE.

Simple way by ADT Bundle

It is the simplest technique to install required softwares for android application. It includes:

Eclipse IDE

Android SDK

Eclipse Plugin

If you download the ADT from android site, you don't need to have eclipse IDE, android SDK and eclipse Plugin because it is already included in adt bundle.

If you have downloaded the ADT bundle, unjar it, go to eclipse IDE and start the eclipse by clicking on the eclipse icon. You don't need to do any extra steps here.

In this page, you will learn what softwares are required for running an android application on eclipse IDE. Here, you will be able to learn how to install the android SDK ADT plugin for Eclipse IDE. Let's see the softwares required to setup android for eclipse IDE manually.

Install the JDK

Download and install the Eclipse for developing android application

Download and Install the android SDK

Intall the ADT plugin for eclipse

Configure the ADT plugin

Create the AVD

Create the hello android application