With the incredible rise of mobile application development over the last decade, Android and iOS have emerged as the two leading operating systems. Android offers much-needed flexibility and has grown to take 86.1% of the market share. The Google Playstore has around 2.87 million apps as of 2020 available to the 2 billion android users across the globe.
These staggering numbers have led to the rise of an entire industry full of opportunity and it is estimated that there are 5.9 million Android developers across the world today. A career as an Android developer is challenging as well as financially fulfilling.
In this article, we answer some of the frequent Android interview questions that are asked by leading organizations around the world. If you are hoping to land a job as an Android developer, this article will help you be better prepared so that you can confidently walk in for your interview and land your dream job.
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Let us now look at some of the most asked questions in an Android developer interview and the expected answers.
Top Android Interview Question and Answers
1. What is Android?
Android is a mobile operating system based on the Linux kernel. It is primarily designed for touchscreen mobile devices like smartphones, tablets, and smart televisions.
2. Can Android be used with languages other than Java?
Android application development can be performed with C/C++ using the Android Native Development Kit. Recently, Google also introduced a programming language called Kotlin which is very similar to Java and can be used to build on Android.
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3. How is the Architecture of an Android Application?
Android app development typically follows the Model-View-Presenter (MVP) architecture. Here, the Model is the data layer, the View is the UI layer, and the Presenter responds to actions performed by the UI layer.
Android app components include:
a) Services that are used to initiate background tasks
b) Intent is what creates the connection between activities and data passing.
c) Notification in form of light, sound, dialog boxes, etc
d) Content providers to share data between apps
e) Resource externalization for strings and graphics
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4. What are Android’s Fundamental Building Blocks?
Some of the core building blocks of Android include:
– Content Provider
5. What is an Application Resource File?
Application resource files are files that include static content that your code can use. This includes layout definitions, bitmaps, animation instructions, user interface strings, and more.
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6. Explain the Lifecycle Methods Involved in the Android Activity?
When you open your Android application, it will go through a series of activities that are as following:
Activity is created in this state.
This is called when the activity is visible to the user.
The activity is in the foreground and the user can interact with it.
Activity is partially halted by another activity.
Activity is completely hidden from the user
From the pause state, the activity is either resumed and becomes visible to the user or is destroyed.
Activity is removed from the memory.
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7. Define Intent.
Intents are used to signal the Android system of certain events that happen. There are two types of intents in the Android operating system:
a) Implicit Intent
b) Explicit Intent
8. How can you Identify View Elements in an Android Program?
The keyword findViewById is used to identify view elements.
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9. What is the use of Bundles in the Android Program?
A bundle in the Android program is usually used to pass data between activities.
10. What are the Various Storage that Android Provides?
a) Shared preferences
b) Internal storage
c) External storage
d) SQLite databases
e) Network Connection
11. How does Android Place Layouts?
Android layouts can be placed in two ways:
a) Declare UI elements in XML.
b) Instantiate layout elements at runtime.
12. Name the Dialog Boxes Supported by Android.
a) Alert dialog box
It can be used to interrupt and ask the user whether to continue or stop a process.
b) Progress dialog box
This is to inform the user of the progress of a particular task.
c) Date picker dialog box
The date picker is a widget that is used to help the user select a date.
d) Time picker dialog box
A Time picker is a widget that is used to help the user select the time.
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13. What is a Singleton Class in Android?
A singleton class in Android is a class that can only instantiate one object. This object can then be shared by all classes. An example could be of controlling concurrency and creating a central point of access for an application to access its data store.
14. What is DDMS?
DDMS stands for Dalvik Debug Monitor Service. It is a debugging tool that comes with Android. It provides an array of services like port forwarding, screen capture, logcat process, thread and heap information on the device, radio state information, incoming call, SMS spoofing, and many more.
15. What is Sleep Mode in Android?
In the sleep mode, the CPU is transitioned into a deactivated mode and does not accept any commands from the Android device. Only the Radio interface layer and alarm remains active in sleep mode.
16. Define Android Architecture.
The Android architecture consists of 4 components
a) Linux kernel
The Android operating system is built over a Linux kernel at its core. It is responsible for power management, memory management, device drivers, and resource access.
b) Native libraries
Native libraries are built on top of the Linux kernel to provide the system with functionalities. WebKit, OpenGL, SQLite, Media, etc are some of these native libraries.
c) Android runtime
Core libraries like DVM are present in the Android runtime.
d) Android framework
On top of the Android runtime is the Android framework. It includes several APIs such as UI (User Interface), telephony, locations, resources, etc.
Applications like Home, contacts, dialer, games, etc are the final layer above the Android framework.
17. Name Some Exceptions in Android
Here are a few examples of exceptions in Android:
c) Inflate Exception
18. What are the Basic Tools used to Develop an Android App?
The Java Development Kit allows developers to create Java programs that can then be run by the JVM (Java Virtual Machine) and JRE (Java Runtime Environment).
b) Eclipse + ADT plugin
Eclipse is an integrated development environment for developing programs. The ADT plugin (Android Development Tools) is a plugin for Eclipse that gives you a powerful and integrated environment to build Android applications.
c) SDK Tools
The Software Development Kit tools are a collection of tools that can be used to develop applications for specific operating systems and devices.
19. What do you mean by a Drawable Folder in Android?
The drawable folder in Android is a collection of drawable resources that is used for graphics that can be drawn. Every drawable is stored as an independent file in the drawable folder. It can be used as a background, banner, icons, splash screen, etc.
20. What is the Adapter in Android?
The adapter, as the name suggests is based on the concept of inheritance. Using the Adapter, you can create a child view on Android to present the items in the parent view.
21. What is Service in Android?
A service is an application component that runs in the background. These background operations could be playing music, handling network transactions, loading a browser tab, etc. Such operations do not provide a UI that the user can interact with. Such a service can run in the background even if the application is destroyed.
22. What is Android Toast?
An Android toast is a small message that is displayed on top of the UI. It is a temporary message that acts like a tooltip. It helps in providing the user with feedback about the operation they are performing.
23. What is AAPT?
AAPT stands for Android Asset Packaging Tool. It is included in the tools/directory of the SDK. The AAPT allows you to view, create, and update Zip-compatible archives. It is responsible for handling the packaging process.
24. What is a Fragment?
Fragments in Android encapsulate views and logic so that it is easier to reuse within activities. Thus, using fragments we can display multiple screens on one activity. Fragments are a combination of XML layout files and a java class, making them very similar to activities.
Tips To Prepare For Your Android Interview
Now that we have seen some of the most frequently asked questions in an Android developer interview, let us try to study some tips that you can use to leave the best impression.
1. Work on your fundamentals
Often, developers have ample surface knowledge but fail at building a strong foundation. What usually separates you from the rest is your strong foundation. Study the core concepts of Java and Kotlin. A strong fundamental will give you an edge over all the other candidates.
2. Work on Data Structures and Algorithm Questions
This is another way to build strong concepts and be prepared for tricky questions that can usually decide the outcome of your interview.
3. Keep Yourself Updated
Read tech-magazines, blogs, and papers to stay updated with the latest in the world of Android and mobile technology.
With these tips in mind and our catalog of questions, we are sure you will be perfectly equipped to land a great job as an Android developer.
Also Read: Android Project Ideas & Topics
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What is Android programming?
Android is an operating system based on the Linux and Unix platforms. It is being developed by Google. The main aim of developing android is to come up with an operating system for mobile devices. This operating system can be used for smartphones as well as for tablet PCs. This operating system is being designed to be lightweight and modular. This operating system uses Java language. Java is a programming language which can be used in different operating systems. Android is the world’s leading mobile operating system. It’s created by Google and is based on the Linux Kernel. An Android application is basically an application written for mobile phones which can be used to play games or make calls.
Which programming languages can be used for Android?
There are many programming languages available for Android, but the two most commonly used programming languages for Android are Java and C. Java is a complex programming language which is very robust and popular programming language, but C is fast, simpler and easier programming language to learn. Both of them have their own pros and cons, but they both can be used to develop Android applications. For many reasons, Java is the most popular for Android programming. (1) Android is Java-based, so it's the most logical choice. (2) It's open source, so it's free for anyone to use. (3) It's object-oriented and dynamically typed, so it's easy for anyone to understand.
What is Kotlin?