TOP 10 Most important Android Interview Questions and Answers

TOP 10 Most important Android Interview Questions and Answers

TOP 10 Most important Android Interview Questions and Answers

Hi everyone,

Before going to start our first android app, we need to know some of the terms or questions related to android that are generally asked during interviews.
So, let's discuss some of them.

Question 1: What is Android? What is the latest version of Android? List all the versions of Android.
Android is a mobile operating system developed by Google. Android is based on Linux Kernel and designed generally for smartphones and tablets.
Latest version of Android is ANDROID 10, releases in September 3, 2019.

List of all android versions:
  • Android 1.5 – Cupcake – 2009
  • Android 1.6 – Donut – 2009
  • Android 2.0-2.1 – Eclair – 2009
  •  Android 2.2-2.2.3 – Froyo – 2010
  • Android 2.3-2.3.7 – Gingerbread – 2010
  • Android 3.0-3.2.6 – Honeycomb – 2011
  •  Android 4.0-4.0.4 - Ice Cream Sandwich – 2011
  •  Android 4.1-4.3.1 – Jelly Bean – 2012
  • Android 4.4-4.4.4 – Kitkat – 2013
  • Android 5.0-5.1.1 – Lollipop – 2014
  • Android 6.0-6.0.1 – Marshmallow – 2015
  • Android 7.0-7.1.2 – Nougat – 2016
  • Android 8.0-8.1 – Oreo – 2017
  • Android 9.0 – Pie – 2018
  • Android 10 – 2019

Question 2: What is an Activity?
An Activity is the screen representation of an application in Android. It basically use as the entry point of the user’s on the application. Each activity has a Layout file in the XML form, where you can design your UI (User Interface). An activity is implementing as the subclass of the Activity.

Question 3:  Explain Android Architecture
Android Architecture represents the different layers in the Android stack. It includes your operating system, middleware and applications. Each layer in the architecture provides different services.
Layers are in bottom-to-top:

1. Linux Kernel: It is the bottom layer. Provide a level of abstraction between hardware and it contains all essential hardware devices like Camera, Display Driver, Flash, Wi-Fi, IPC etc.
2. Android Libraries: It provides java based libraries, like
android.app- provide access to app model
android.content- published & messaging between applications. etc.
3. Android Runtime: Provide a key component called DalvikVirtual Machine. Which is a kind of Java Virtual machine specially designed and optimized for Android.
4. Application Framework: It provides higher level services to the application in the form of Java class.
Services are like-
  • Activity Manager- control all lifecycle
  • Content Provider- Allow application to share data with other app
  • Resource Manager- provides access to resources like strings, colors, UI layout
  • Notification Manager

5. Application: It is the Top layer of the architecture. Home, Contacts, Phone, Browser etc.

Question 4: What is AAPT?
Android Assets Packaging Tool provides developer with the ability to deal with zip compatible archives.

Question 5: What is Emulator?
Emulators is the safe place to testing code for your application

Question 6: What are the items that are very important for every Android projects?
  • Android Manifests
  • build.xml
  • bin/
  • res/
  • assest

Question 7: What are the essential states of activity?
  • Active: if the activity is at the foreground.
  • Paused: if the activity is at the background and still visible.
  • Stopped: if the activity is not visible and therefore is hidden by another activity
  • Destroyed: when the activity process is killed or completed

Question 8: What is ANR?
Android Not Responding. A dialog appears to the users when app have been not unresponsive for a long time.

Question 9: What is APK?
Android Packaging Kit. It is the compressed file format of android, where resource files, java files, gradle files are compressed in it.

Question 10: What is the life cycle of android activity?
  • onCreate(): in this state, activity is created
  • onStart(): activity become visible to the users
  • onResume(): activity in the foreground and user can interact with it
  • onPause(): android activity is partially above another activity.
  • onStop(): activity is totally hidden from the users
  • onDestroyed(): activity is destroyed or removed from the memory.

Leave comments if you have any query.

In the next blog, we will discuss about Layouts in Android. CLICK HERE

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