Today, Android’s share of the global operating system market amounts to 42.6%. For millions of small and mid-size businesses, creating a mobile app is an effective way to reach new customers, optimize working processes, and ultimately increase profit.
Whether it’s a CRM system to enhance your business-customer connection, a corporate app to optimize and automate your internal processes, or you just have a brilliant idea for a mobile game – you need professionals to make it a reality.
2020 alone was marked by 218 billion app downloads worldwide.
In 2019, Statista reported 23.9 million software developers worldwide. Choosing your trusted tech partner appears to be a challenging task. Here’s a guide on how to hire an Android developer: the role’s overview, essential skills, and aspects to consider for the recruiting process.
Choosing between native android and cross-platform development
In 2020, We Are Social reported global penetration of unique mobile phone users to be as high as 66%. It creates unlimited possibilities for businesses to reach out to new customers. If creating a mobile application is part of your business plan, and you decide on Android, it’s good to start by defining if you need a native Android or a cross-platform app.
- Native Android development
Native development refers to creating an application for one operating system using the official tools of the chosen OS. For example, native languages for Android are Java and Kotlin. The native application works only on its platform – one code for one system.
- Cross-Platform development
As the name suggests, cross-platform development is a way to create an application that can be adapted to multiple OS. By analogy, one code is used to create different builds for Android, iOS, or Windows Phone. Developers use various tools and instruments to build cross-platform apps, such as Flutter or React Native frameworks.
Although cross-platform tools save time, native development is more popular among programmers, as native apps can have more device-specific features, better looks, and exceed cross-platform solutions in performance. Besides, supporting cross-platform code is much more difficult than native. Let’s focus on native Android developers’ roles, skills, and responsibilities.
Native Android developer responsibilities
In general terms, an Android developer’s goal is to create an application that solves users’ problems and makes their life easier. They should ensure that apps perform on old and cheap devices without crashing, are user-friendly, and are easy to learn.
Android developers create, update, and improve mobile applications and software for smartphones, tablets, e-books, game consoles, and other devices running on the Android operating system.
According to experience and skill level, software developers are usually divided into junior, mid-level, and senior roles. It determines their tasks and responsibilities. Read more about software developer levels in our article 5 Software Developer Levels: Whom to Choose.
The list of an Android developer’s responsibilities may vary depending on their experience, company size, project complexity, or contract type. There are, however, core responsibilities associated with this role. They include:
- Writing reusable and reliable code in one or both official Android languages;
- Translating wireframes and designs into functional code;
- Creating new user interfaces;
- Maintaining code quality according to the standards;
- Achieving high performance even on budget devices;
- Identifying and fixing bugs;
- Writing unit and UI tests;
- Collaborating with backend engineers, QA teams, and designers;
- Identifying, prioritizing, and executing tasks in the software development life cycle.
Large software development companies have big teams to maintain an agile working environment. Often, it means Team leaders assign a narrow task-set to each team member: some write the code, others test it, some are responsible for updates, and so on. In smaller companies, however, one developer may turn into a jack-of-all-trades performing most of the tasks.
What are the essential skills to hire Android developers
Hiring an Android developer requires a clear understanding of the competencies necessary for this role. Project goals differ, which impacts the requirements set.
Must-have technical skills for Android developers
However, there’s a list of core hard skills mostly mentioned by industry leaders. If you are looking for an Android developer, you should consider the following:
- Knowledge of Java and/or Kotlin.
Java and Kotlin are the two official languages of Android development.
- Strong knowledge of Android SDK.
The Software Development Kit (SDK) is a set of tools for creating software for a specific platform. In general, it can include a compiler, a debugger, various libraries, etc. Android SDK contains Java code modules that give the programmer access to mobile device functions, third-party services, and the like.
- Experience with different versions of Android and various screen sizes.
Solving the fragmentation problem is the key here, as developers have to ensure flawless functionality on thousands of Android devices supporting different, often old, OS versions.
- Experience with Android Studio.
Android Studio is an official integrated development environment (IDE) from Google. In Android Studio, you can create applications for phones, tablets, Android Wear, Android TV, and Android Auto. Structured code modules allow you to divide a project into functional blocks. This IDE is suitable for both beginners and advanced developers.
- Good knowledge of APIs and databases.
API serves as a data highway that connects an application to third-party services or ties together different internal blocks. A good API is reliable, logical in its structure, easy to work with, and shows excellent performance
- Understanding of Google’s Android interface guidelines and design principles.
Familiarity with official Android documentation is essential for creating high-quality applications in line with the standards.
- Good understanding of additional sensors’ functionality – accelerometers and gyroscopes.
A huge part of modern mobile development uses additional sensor integrations to enhance apps’ performance and increase functionality.
- Proficiency in using code versioning tools like Git.
Git is a free and open-source distributed version control system designed to handle small to very large projects with speed and efficiency. It makes things like collaboration and version monitoring much easier.
- Familiarity with the open-source Android ecosystem and libraries.
Open-source Android libraries are designed to decrease development time and use resources more efficiently. In many cases, knowledge of particular libraries is necessary to catch up with the team and work style.
A big part of mobile application development is understanding and translating business requirements into the project’s technical aspects. That’s why experience working in corporate and business environments may become a cornerstone in making a final decision.
Android component libraries every mobile developer need to know
As mentioned above, proficiency in working with specialized Android libraries is another essential skill that distinguishes the best candidates. A search for “android-library” on GitHub currently provides 4,669 results for public repositories. The most popular libraries among professionals include:
- Glide – an image caching and loading library for Android that focuses on smooth scrolling;
- Dagger – a compile-time, dependency injection framework;
- DBFlow – a simple Android library for working with a database;
- AndroidUtilCode – a utility Android library for improving development efficiency;
- Google Analytics – a popular business and marketing tool integrated into your Android app;
- LeakCanary – an Android memory leak detection library;
- Logger – a simple Android logger;
- Stetho – a powerful Android debug bridge;
- Retrofit – Android and JVM type-safe HTTP client;
- Moshi – JSON library for Java and Kotlin.
In many cases, specific problems require using less known or less popular libraries or frameworks. It’s vital even for highly experienced developers to learn new tools in a short time. Together with problem-solving thinking and teamwork spirit, it’s one of the most important soft skills for an Android developer. Although many candidates often neglect soft skills, it takes more effort and longer time to train them than to acquire a new tech skill.
How to interview Android developers
Hiring IT specialists can turn into a long and exhausting process. To understand if a developer conforms to the level specified in the CV it is reasonable to interview a candidate.
Such interviews take place if the candidate is short-listed. It’s a way to meet the candidate in person and give them a chance to elaborate on the information provided in the CV. Here are some question examples for inspiration.
Junior Android developer interview questions
Questions for Junior developers should cover the basics of the programming language as well as Android development. Try to come up with questions that will allow multiple correct answers.
Q1: You need to make a scrollable list. Which elements are you going to use?
A1: It’s good if the candidate mentions ListView or RecyclerView. Additional points go for explaining the difference between these objects – that RecyclerView was created as an improvement to ListView, so it is a lot easier to use due to its automatic recycling mechanisms and reusing item views.
Q2: What is View? What can you do with it?
A2: It is a base class for multiple widgets like buttons, text fields, lists, etc. For using View, you can set its properties (like dimensions, position, IDs, and many more), attach Events to it, apply Themes and animation, create custom view components, and much more. Do not expect the developer to mention all of these points, but the mentioned ones should be correct.
Also, questions about the programming language basics and OOP are a must:
Q3: What are the basic data types in Kotlin?
A3: “Numbers, characters, Booleans, arrays, and strings” (in any order).
Q4: What is the difference between val and const?
A4: Val is used for defining runtime constants, while Const is a keyword for compile-time constants.
Q5: What visibility modifiers are available in Kotlin?
- Private: only visible inside this class (and its members).
- Protected: the same as private, but also visible in subclasses.
- Internal: visible inside the same module.
- Public: visible to everyone.
Middle Android developer interview questions
Middle-level developers must have some experience in real projects to handle more abstract questions or concrete questions on a narrow topic. Appreciate the success stories from the previous projects and let the candidate tell them freely.
Q1: Why and how would you create a custom view?
A1: Custom views are needed to make reusable UI components (for example, alike-looking buttons that can be redesigned from a single instance) or to make a completely new object type that is not provided by the Android ecosystem. Custom views are created through extending concrete Widget class (like Button or TextView) or extending the base View class. Candidates score additional points for mentioning examples of previously created custom classes and the positive/negative impact of using them.
Q2: What are Intents?
A2: Intent is a messaging object that is used for communication between app components. They are used to open new pages, launch background tasks, or send messages to other apps. There are two types of intent:
- Explicit intents strictly specify the application that will satisfy the intent. It is usually used to start some process inside your own app, calling it by a fully-qualified component class name. It is commonly used to handle responses to user actions.
- Implicit intents do not specify a particular component or application, but rather declare which action must be performed. In simple terms, it says, “I need to show the user’s location on the map, and any capable application should do it.”
Q3: How to run tasks in the background correctly?
A3: Tasks with long execution times like accessing storage or making network requests should be delegated to a background thread. For this purpose, one can use Kotlin coroutines or Threading in Java. To continue handling long-running tasks even when the user switches applications or restarts the device, WorkManager can be used. For specific cases like continually playing media, foreground services are a way to go. You can also ask about some success/fail stories from previous experience as this topic is quite rich.
Senior Android developer interview questions
Broadly experienced Senior developer should be able to convince you in their qualification by just telling about their previous experience. You don’t need strictly-formed questions on narrow topics. Talk about user stories and business requirements, for instance:
Q1: Our app needs a high level of security. What needs to be done?
Q2: Users are leaving bad reviews for our application, saying performance is poor even on middle-range devices. What is the problem?
Q3: We often see OutOfMemoryError in our monitoring tools. What is it? What to do?
In interviews, it is also necessary to test the practical skills of the developer.
In our article Top 8 Best Coding Interview Platforms you can read more on what coding tasks are, why they are important, and where to find them.
How much does it cost to hire Android developers
Salaries and rates are often a matter of discussion and depend on many factors, among the most important are region and level of the developer.
Hourly rates of Android developers are listed below. The data is taken from Payscale, Glassdoor, Indeed, Salaryexplorer.
The cooperation model will determine where to find a developer. Read more in our article How and Where to Find Software Developers Who Meet Your Needs
Creating Android applications requires a deep understanding of programming and design. If creating a mobile app is part of your business development strategy, you need to determine how to hire an Android developer.
A variety of device types from different manufacturers, often outdated OS versions, Android platform fragmentation, and thousands of third-party open-source resources – many aspects may complicate your choice. They also can make it easier if you know what you are looking for.