Android is a popular mobile operating system and its developers are often in high demand in today’s mobile society. If you want to pursue a career as an Android application developer, knowing how to answer some of the top interview questions can help you feel more confident as you approach your interview.
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In this article, we provide a list of common Android interview questions and sample responses to help you prepare.
Android interview questions and answers
Here are nine common Android interview questions and how you can respond to them:
1. What is Android?
One of the first questions the interviewer is likely to ask is how much you currently know about Android. You may need to know the definition, when developers use Android, and why you would use it. Consider discussing specific examples of when you’ve used the platform and for what reasons.
Example: “Android is an open-source platform on Linux that is free. This mobile operating system gives a free software development kit to any developers who want to use it. This is an advantage for developers and companies since it decreases the costs of licensing and development. I’ve used it in my personal development projects to create applications with a variety of helpful tools.”
2. What are fragments?
You may use fragments often as an Android developer. Knowing the definitions and when to use them can improve your answer during your interview. In your answer, you can explain several features of them and the ways you’ve utilized them in your own work to demonstrate your familiarity.
Example: “A fragment is a section of the user interface. You can use multiple fragments within one activity. It is possible to remove or add fragments while an activity runs. A fragment has a separate lifecycle but is always used within an activity. I sometimes use fragments to organize the User Interface of the content and functions of an app so that it can be easily navigated.”
3. Can you explain when to use a fragment compared to an activity?
As a developer, you often need to know when you should use a fragment and when you should use an activity. An effective answer would list different scenarios where you would use either one.
Example: “The code that builds an activity is more involved than the code that builds a fragment. You must pause, stop or destroy the old activity while you create the new activity. Using an activity only when you need to switch the entire screen is a smart technique. Otherwise, you should use fragments in all other cases. Developers often use fragments when using a navigational method or if the user would benefit from putting two layouts next to each other.”
4. When replacing a fragment, how do you know the user can get back to the last fragment when they press the back button?
Understanding the life cycle of fragments is essential for a developer. You may need to explain that you know this as well as what the back stack is because this function may be necessary to use daily.
Example: “You should save each fragment transaction to the back stack to have the back button get the user to the last fragment. You can do this by calling ‘addToBackStack()’ before you commit that transaction.”
5. What are the advanced features of Android, and what are their benefits?
Android is popular among developers as it has a variety of advanced features. You can list a few of these in addition to what advantages you think Android has. Your answer can define specific applications and explain why they are useful.
Example: “There are many advantages to using Android. ThreadPool is where a group of worker threads and a task queue run numerous parallel instances of a certain task. This ability increases the performance of an application when you use it correctly. Using ThreadPool is also more efficient compared to having various operations waiting to run for one thread. This also helps you prevent the tedious overhead of building and then destroying a thread each time you need a worker thread.”
6. What are potential errors you may encounter?
Encountering errors is a normal part of being a developer. Even the most experienced developers may run into issues, but knowing how to address these issues is what makes an effective and productive developer. You can give an example of a specific error and how you would fix it.
Example: “A common Android error is an Application Not Responding error. When I see this in my work, I know not to perform long or intense operations on the main thread. This error occurs when the UI is unresponsive for more than five seconds due to something blocking the main thread. A solution to this is to move the majority of work off the main thread.”
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7. What are views and how are they used?
Views are an essential part of Android development. You can explain what they are, what the process for creating them is, and how you can optimize their usage.
Example: “A view is part of the Android User Interface that responds to user inputs. When creating a view, you should subclass the view that is closest to the custom component you want to build. Once you extend the class, you can build a res/values/attrs.xml file and declare the attributes you intend to use with the custom view.
You can optimize view usage by checking for excessive overdraw by installing the app on an Android device. Next, you can enable the “Debug GPU Overview” option. Another way is to flatten the view hierarchy. You can do this by inspecting the view hierarchy by using the “Hierarchy Viewer” tool in Android Studio.”
8. Do you know how to create a bound service?
Developers often use bound services in Android applications. You can explain how you would build one and give specific steps involved. You can also frame your explanation of the process by demonstrating how you’ve built a bound service in the past.
Example: “The first step when creating a bound service through Android Interface Definition Language is defining the AIDL interface for a .aidl file. You then save the file in the src/ directory of the application that hosts the activity and any other application necessary to bind the service. Next, you can build the application and use Android SDK tools to create the IBinder interface file that goes in the gen directory.”
9. What’s the difference between an explicit and an implicit intent?
You may use different intents in an Android application depending on what function you are creating. You can explain what the difference is between implicit intent and explicit intent and when you would use each.
Example: “An explicit intent tells the system which system component or activity you should use to respond to the intent. Implicit intent is where you state what action you want to perform. The Android system then checks what registered components can control that action. The majority of the time, you will likely use an explicit intent to begin components in your application. You would use implicit intents when you are trying to communicate with other components from a third-party application.”
I hope you find this article helpful.
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