Interview Questions for Android Developers

Android has the largest installed user base of any mobile platform in the world. As a result, developers who have mastered the OS are in great demand, and can command salaries ranging from $100,000 to $150,000 per year.

Interview QsOf course, when it comes to getting a job, you’ll have to demonstrate your expertise – indeed, your passion — for the technology and pass a technical interview to score top pay. That can be challenging. Not only has Android been updated several times since the first version was released in 2008, but device fragmentation is a challenge as each manufacturer tweaks the software.

We asked Ryan Unger, co-founder and CTO of mobile marketing firm Punchkick Interactive to share a few common interview questions for Android developers and the types of answers he’s looking for. He also shared some general tips for mastering technical interviews.

What‘s the last project you worked on in your spare time without pay?

  • What Most People Say: Um… I worked on one two years ago.
  • What You Should Say: I was working on an open source app last night. Would you like to hear about it?
  • Why You Should Say It: The fact that you want to program in your spare time and voluntarily upgrade your skills communicates passion and hunger, says Unger, who describes this as a black and white question with only one acceptable answer.

Simply building an app was enough to score a job in the early days, Unger says. Today, though, it’s about writing more efficient code and what you’ve done with the app that matters. And you can’t keep up by resting on your laurels.

“For example, I don’t want a developer with two years’ experience five times,” Unger says. “I want a developer with 10 years of experience once.” Hint: He’s looking for a professional who’s taken his or her game to a higher level.

Why does every Fragment need a default parameterless constructor?

  • What Most People Say: I’ve always done it that way.
  • What You Should Say: The FragmentManager uses the default constructor when recreating Fragments across orientation changes and also during other times, such as to support dynamic and flexible UI designs on large screens.
  • Why You Should Say It: “This is a relatively easy question that illustrates if someone has table-stakes knowledge of Android,” Unger explains. “Your answer should show that you’re cognizant of the need and purpose of flexible layouts.”

“There are tons of screen sizes on the market, and flexing the size is more difficult,” Unger says. “You need to show that you understand how the language works. And you can’t do that by simply regurgitating canned answers or blindly following instructions.”

Do multiple AsyncTasks run in parallel or serially?

  • What Most People Say: They run in parallel or they run serially (but they don’t explain why).
  • What You Should Say: It depends. On early Android, AsyncTasks were run serially. Then in Donut this changed to multiple threads running in parallel. But in Honeycomb, AsyncTasks run on a single thread by default, though they can be overridden using the special .executeOnExecuter() method.
  • Why You Should Say It: Unger admits that this is a difficult question, as you need experience with several versions of Android to answer it. Most of today’s Android developers weren’t coding before Donut, he notes. Additionally, even an experienced Android developer could easily forget to mention the .executeOnExecuter() method.

Any time the situation is gray or you don’t understand the question, ask for more specifics before providing an answer. Or demonstrate your technical knowledge by providing several answers.

Unger says “flipping the script” on the interviewer shows hunger and drive. Also, if you don’t know the answer to a question, admit it. Just be sure to exhibit your professional curiosity by asking for the answer.

“The difference between an intermediate engineer and an advanced engineer is the advanced engineer can tell you why it’s done that way,” Unger says. “They don’t simply copy and paste code from Stack Overflow when they’re stumped. They dig deeper to find out why the code is written that way.”

Comments

  1. BY Rajesh says:

    good knowledge for helping interview.

  2. BY Joe says:

    In my opinion some of these questions are bad to determine if a developer is good. Why would you expect a candidate to know how async task work in donut ? In your organisation are you targeting donut? As a developer I am so busy I don’t have time contributing to open source last night does that mean I don’t have a passion for what I do almost everyday? If I want to hire a developer I will look for someone that understand and solve business problems while making the code they write simple and efficient. That is just my opinion. In my daily work I come across developers that make life complicated, simplicity is beauty.

  3. BY rock says:

    Async tasks run parrallely or serially depends on the number of CPU in device .
    When we say they are running parallely It means they seems to run simultaneously,
    But actually at a time onlr one thread is running .CPU do time slicing for parallel threads
    and so they seems to run in parallel.

  4. BY Unnikrishnan says:

    Hii, this is indeed a very good post. Only an experienced developer will be able to answer these application level questions.

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