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android Interview Questions and Answers

Each android Interview Question Sets contains 12 questions.

1)   What is Android?

Android is a mobile operating system developed by Google, based on the Linux kernel and designed primarily for touchscreen mobile devices. It has been equipped with rich components that allows developers to create and run apps that can perform both basic and advanced functions.

2)   What is the google Android SDK?

The Android software development kit (SDK) includes a comprehensive set of development tools which is a toolset that developers need in order to write apps on Android enabled devices. It contains a graphical interface that emulates an Android driven handheld environment, allowing them to test and debug their codes.

3)   What is the Android architecture?

Android architectue is divided into following five parts.
linux kernel
native libraries (middleware),
Android Runtime
Application Framework

4)   Explain .apk extension.

Android application package (APK) is the package file format used by the Android operating system for distribution and installation of mobile apps and middleware. APK files are a type of archive file, specifically in zip format packages based on the JAR file format, with .apk as the filename extension. The MIME type associated with APK files is application/

5)   What is AAPT?

AAPT (Android Asset Packaging Tool) allows you to view, create, and update Zip-compatible archives (zip, jar, apk). It can also compile resources into binary assets. It is the base builder for Android aplications.

6)   What is the importance of having an emulator within the Android environment?

Basically emulator helps you to run your application there itself in the PC, you needn't require any android phone to test your application.
Developers use emulator for quick testing of the apk at the machine itself.

7)   What method does Android follow to track applications?

It is done by assigning each application with a unique ID (referred as Linux User ID).

8)   What is the use of an activityCreator?

An ActivityCreator is the first step towards the creation of a new Android project. It is made up of a shell script that will be used to create new file system structure necessary for writing codes within the Android IDE

9)   Describe activities?

Activity - represents the presentation layer of an Android application, e.g. a screen which the user sees. An Android application can have several activities and it can be switched between them during runtime of the application.

10)   What are intents?

An intent is an abstract description of an operation to be performed. It can be used with startActivity to launch an Activity, broadcastIntent to send it to any interested BroadcastReceiver components, and startService(Intent) or bindService(Intent, ServiceConnection, int) to communicate with a Background Service.

11)   What is referred to Explicit and Implicit Intent?

Explicit Intent: Explicit intent names the component.
Implicit Intent: Implicit Intents have not specified a component.
eg: The java class which should be called Implict intent asked the system to perform a service without telling the system which java class should do this service.

12)   Differentiate Activities from Services?

Activity : An activity represents a single screen with a user interface. For example, an email application might have one activity that shows a list of new emails, another activity to compose an email, and another activity for reading emails. Although the activities work together to form a cohesive user experience in the email application, each one is independent of the others. An activity is implemented as a subclass of Activity.
Service: A service is a component that runs in the background to perform long-running operations or to perform work for remote processes. A service does not provide a user interface. For example, a service might play music in the background while the user is in a different application, or it might fetch data over the network without blocking user interaction with an activity.A service is implemented as a subclass of Service

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