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The Ultimate Guide for Hiring Java Developers
Java ranks among the top 3 programming languages in the world. It's a preferred choice across various industries, powering everything from large-scale enterprise systems to mobile applications.
With its widespread use, you might assume that finding skilled Java developers would be easy. However, that's not the case. The demand for top talent is high, and finding developers who both understand Java and have experience with the right frameworks or enterprise systems can be a challenge.
At BairesDev, we've onboarded hundreds of top-notch Java developers since 2009. So we can tell you that the best candidates have a mix of broad expertise and specialized skills.
Not sure what specific skills to look for? We’re here to help. In this guide, we cover the key technical and soft skills plus potential interview questions to help you identify and then hire Java developers who are the best fit for your team.
Before You Start Hiring
Project or Team Requirements
Java’s versatility means specifics matter. Are you building a new application from scratch, or will the developer be enhancing an existing system? Do you need expertise in backend development, or are you focused on mobile app development using Java for Android? Detail your project specs because they will influence the “type” of Java developer you’re looking for
Niche Experience in Java
Consider whether your developer needs niche experience for your project. For instance, if you’re dealing with real-time data processing, look for someone well-versed in concurrency and Java's multithreading capabilities. If your project involves cloud-based solutions, seek out a developer familiar with cloud platforms like AWS and Java-based microservices.
Modernization
If you’re looking to upgrade or refactor legacy systems, your ideal developer should have experience in modernization projects. This includes familiarity with the latest Java versions, an understanding of modern architectural patterns like microservices, and experience with tools like Docker and Kubernetes for containerization and deployment.
Experience with Your Methodology
Does your team follow Agile, Scrum, or DevOps methodologies? Java developers with experience in your preferred methodology onboard faster. For example, a candidate with an Agile or Scrum background will be accustomed to iterative cycles and rapid changes. Those with DevOps experience will be more comfortable with CI/CD pipelines and automated testing.
Experience in Your Industry
If your project involves industry-specific regulations or standards—such as data security in healthcare or financial transaction processing in finance—it’s important to hire Java developers who understand those complexities. Developers with industry experience will be better prepared to meet compliance requirements and build solutions that address niche needs.
19 Skills Every Java Developer Should Have
Java is incredibly versatile and used for everything from massive enterprise-level solutions to mobile development. Because of this versatility, the best Java developers have a blend of skills that go beyond Java basics.
To help you find top talent, we’ve put together a checklist. From core functionalities to necessary frameworks and the critical thinking skills necessary for sound architectural decisions, here are some essential technical and soft skills needed for Java development:
Technical Skills to Look for in Your Ideal Java Developer
1. Mastery of Java Core
Core Java is the foundation of all Java applications. Developers who’ve mastered Java Standard Edition (SE) understand essential programming concepts like object-oriented programming, data types, collections, exception handling, and features introduced in Java 8, such as streams and lambda expressions. These skills help them write clean code and troubleshoot issues effectively.
2. Experience with Back-end Java Frameworks
To build scalable and secure server-side applications, look for Java developers proficient in back-end frameworks like Spring and Hibernate. These frameworks help reduce repetitive code and provide powerful tools for integrating databases and managing application logic.
3. Experience with Front-End Java Frameworks
If you want apps with engaging user experiences, consider Java developers familiar with front-end frameworks like Google Web Toolkit (GWT), Thymeleaf, and Vaadin. With GWT, devs can write Java code that compiles into JavaScript, ensuring compatibility with browsers. Thymeleaf is often used in Spring Boot applications for rendering HTML, and Vaadin lets developers build full-stack apps entirely in Java.
4. Proficiency in Multithreading and Concurrency
Users expect your applications to be quick and responsive. Developers with skills in multithreading and concurrency know how to build apps that handle multiple tasks simultaneously and maintain a high-quality user experience even under a heavy load. This is especially relevant if your apps have to accommodate high traffic or process large amounts of data in real time.
5. Understanding of Java Virtual Machine (JVM) and Java Runtime Environment (JRE)
A good grasp of the JVM and JRE allows developers to optimize how Java applications run. The JRE provides essential libraries, while the JVM executes Java bytecode. By understanding these components, developers can manage memory effectively, handle garbage collection, and avoid performance issues so that applications run smoothly across different platforms.
6. Experience with RESTful APIs and Web Services
RESTful APIs and web services create smooth connections and data exchange between your systems. By using stateless RESTful APIs, developers can create scalable applications that handle high traffic well, providing real-time updates and a responsive experience for users. Their familiarity with web services helps them integrate other critical systems like databases, payment gateways, social media platforms, cloud platforms, and microservices.
7. Database Management and ORM
Understanding how to work with relational databases like MySQL or PostgreSQL lets developers store, retrieve, and manipulate large amounts of data. ORM tools, such as Hibernate, help simplify this process by allowing developers to interact with databases using Java objects instead of complex SQL queries. This makes their code cleaner and easier to maintain. It also improves application performance through optimized queries and proper indexing.
8. Familiarity with Build Tools (Maven, Gradle)
With build tools like Maven and Gradle, Java developers can automatically compile code, run tests, and package applications. Build tools manage external libraries and resolve dependencies, which helps developers minimize version conflicts and keep project environments consistent. Plus, the tools integrate with CI/CD pipelines, so developers can quickly test and deploy code changes.
9. Version Control Systems (Git)
Maintaining code integrity is always essential, and it’s even more so in team environments. You want developers with experience using Git to manage code versions, collaborate on teams, and track changes and integrations.
10. Unit Testing and Test-Driven Development (TDD)
Look for developers who focus heavily on TDD and use tools like JUnit to write tests that catch bugs early. These skills help them produce reliable code from the start, which minimizes issues later in the development lifecycle.
11. Knowledge of Microservices Architecture
With microservices, teams can deploy updates and new features more efficiently. So look for devs who know how to break down monolithic applications into smaller, loosely coupled services that can be scaled independently. Key tools include Spring Boot or Micronaut.
12. Familiarity with Cloud Platforms
As businesses increasingly move to the cloud, cloud-savvy Java developers play a role in digital transformation initiatives. Those with experience in AWS, Google Cloud, or Azure can deploy and manage Java applications in cloud environments and leverage cloud-native tools for scaling and performance optimization.
13. Experience with DevOps Tools
To make sure Java applications integrate smoothly into CI/CD processes, seek out Java developers with experience in DevOps tools like Docker, Kubernetes, and Jenkins. With these technologies, they can automate deployment and streamline the development pipeline.
14. Jakarta EE (previously Java EE)
Jakarta EE is a set of specifications that extend the Java SE platform to support large-scale, multi-tiered applications. Developers familiar with its components—Servlets, JavaServer Pages, Enterprise JavaBeans, and Java Persistence API—have the skills to build complex enterprise-level applications with robust business logic.
15. Performance Optimization and Profiling
Look for Java developers who can profile and optimize applications using tools like VisualVM or JProfiler. With these tools, devs can dramatically improve performance, reduce memory consumption, and keep your application running efficiently, even under heavy loads.
Soft Skills to Look for in Your Ideal Java Developer
16. Problem-Solving
From debugging multithreading issues or optimizing complex applications, Java developers face tricky challenges daily. To keep your projects moving forward, seriously consider those who show they can tackle issues head-on and propose creative solutions.
17. Critical Thinking
Whether you’re designing a scalable microservices architecture or optimizing database interactions, developers who make smart architectural decisions are an asset. To find them, listen to how they evaluate options, weigh trade-offs, and devise long-lasting solutions.
18. Communication
When working across teams, strong communicators create an atmosphere where ideas are shared easily and problems are solved faster. Look for developers who clearly explain technical choices and communicate concepts well to all team members, including non-technical ones.
19. Resilience
Setbacks are normal. Developers need resilience to deal with issues like bugs, sudden changes in project scope, and performance problems. Signs they’re resilient? They tackle tough tasks without losing momentum, find workarounds, and keep their team motivated along the way.
9 Questions to Identify Top Java Developers
When interviewing Java developers, it's important to ask questions that first assess the candidates' technical skills and knowledge. Employers looking to hire Java developers will also usually conduct a coding test to further assess specific on-the-job knowledge.
The following set of questions aims to uncover not only the developer's technical knowledge but also their problem-solving abilities, teamwork, communication skills, and adaptability—all crucial traits for success in a collaborative environment.
Here are a few examples of technical interview questions:
1. How do you manage memory and garbage collection in Java?
I keep an eye on object creation and make sure unnecessary objects are cleared up quickly. I understand how garbage collection works in Java, and I try to minimize the impact by avoiding memory leaks. In one project, we were running into memory issues with large data sets. I optimized memory usage by refactoring the code to reuse objects where possible and by using weak references for certain data structures that didn’t need to be kept in memory for long. It significantly reduced memory usage and improved performance.
2. When have you used multithreading in Java, and what challenges did you face with concurrency?
I’ve used multithreading a few times, particularly when working with real-time data processing. In one case, I needed to improve the performance of a service that handled multiple concurrent requests. One challenge I faced was avoiding race conditions. I tackled that by using Java’s synchronized keyword to ensure that critical sections of the code were handled properly. I’ve also used ConcurrentHashMap and other utilities from java.util.concurrent to safely manage shared resources.
3. Have you ever had to troubleshoot a performance issue in Java? What tools did you use, and what was the outcome?
Yes, in one project, our team noticed significant performance slowdowns as the application scaled. I used VisualVM to profile the application and identified that a specific method was causing a bottleneck due to inefficient memory use. I optimized the algorithm and reduced the frequency of object creation, which immediately improved performance.
4. In a microservices setup, how do you manage communication between services in Java?
I’ve mainly used REST for communication between services, but I’ve also worked with message brokers like RabbitMQ when services needed to communicate asynchronously. As for tools, I’ve used Spring Cloud for service discovery and load balancing with Eureka, which made managing services a lot easier. I’m also familiar with using gRPC for more efficient communication in certain use cases.
5. How do you make sure your Java code is easy to maintain and scales long-term?
I follow best practices like writing clean, modular code and adhering to SOLID principles. I also document the code properly so it’s easy for future developers to pick up. For example, in one project, we used a microservices architecture to ensure scalability and keep each service independent. We made sure that each service was loosely coupled and could be maintained or scaled without affecting the others. This approach really paid off when the project grew, as it was easy to update individual services.
6. When you have competing priorities on a Java project, how do you make sure you deliver on time without sacrificing quality?
This question evaluates a candidate’s ability to prioritize tasks, balance deadlines, and maintain high-quality code, especially in high-pressure environments.
7. Have you ever faced a significant setback with a Java project? How did you respond to keep the project on track?
This question explores how a candidate handles setbacks, recovers from mistakes, and stays motivated to find solutions without letting the project lose momentum.
8. The last time project requirements or technologies changed midway through a Java project, how did you adapt?
This question gauges how the developer deals with changes in scope or technology and how well they pivot to make progress and maintain quality.
9. Have you ever had a disagreement with a teammate about how to approach a Java-related task? How did you resolve it?
This question examines the candidate's conflict resolution skills, specifically how they handle differing opinions, maintain collaborative relationships, and keep conflicts from derailing project progress.
FAQ
What’s the biggest benefit of using the Java programming language?
Java is a high-level, object-oriented programming language that was designed to be platform-independent. The biggest benefit? Applications written in Java can run on any system with a Java Virtual Machine (JVM). This allows developers to write code that runs on different operating systems without modification.
What is Java used for in software development?
Java is widely used for building enterprise-level applications, mobile apps (especially Android), web applications, and large-scale systems. Its libraries and frameworks, like Spring, Hibernate, and Struts, make it a strong choice for developing complex, scalable applications.
Due to its memory management and security features, Java is also popular for apps that need to reliably handle a large number of users, data, or tasks without crashing. That’s why it’s often used in enterprise-level systems, banking applications, or any other software where stability and security are crucial.
What’s the difference between Java developers and Java programmers?
A Java programmer focuses mainly on writing and fixing code based on project requirements. They’re usually more task-oriented and handle the technical aspects of coding.
On the other hand, a Java developer takes on a broader role, working through the entire software development process—coding, designing, testing, and even maintaining the application. Java developers also collaborate with different teams and contribute to bigger decisions, like how the system is structured or which technologies to use.
How do I assess the technical experience level of a Java developer?
When assessing technical experience, look for knowledge of core Java concepts like object-oriented programming, multithreading, and memory management. Check their experience with frameworks relevant to your needs and ask about specific projects they’ve worked on. During interviews, focus on their previous roles, the challenges they’ve solved, and their involvement in design or architecture decisions.
We also recommend using a coding challenge and technical interview to see how they solve problems in real-life scenarios. These tests help assess their coding efficiency, decision-making under pressure, and how they handle typical Java development tasks.
How do I determine which frameworks are important when hiring Java developers?
The answer depends on the specifics of your project. For web development, your developer needs to use Java web frameworks like Spring MVC, Vaadin, or JSF. If you're working on enterprise-level applications that require complex business logic and security, frameworks like Spring or Jakarta EE (previously Java EE) are more relevant. For database-heavy projects, look for experience with persistence frameworks like Hibernate or JPA.
Can Java developers work on machine learning projects?
Yes. Java has machine learning libraries (Weka, Deeplearning4j, and Apache Spark’s MLLib) that developers use to build and integrate machine learning models into applications. If you need to add features like predictive analytics or recommendation systems, experienced Java developers can build those capabilities in your application.
Should Java developers know other programming languages?
It’s helpful for Java developers to know other programming languages. While expertise in Java is important, understanding additional languages can improve their problem-solving skills and make them more flexible for different projects. For instance, knowing JavaScript is useful for web development, as many projects involve front-end coding. Languages like Python or R are valuable for work in data science and machine learning.
What’s the difference between a junior Java developer and a senior Java developer?
The main difference is experience and the level of responsibility. Junior Java developers are typically newer to the field and focus on writing code, fixing bugs, and working on smaller, well-defined tasks. They often follow guidelines set by more experienced developers.
Senior Java developers, on the other hand, have years of experience and take on a much broader role. Beyond coding, they are also involved in system design, architecture decisions, and more complex tasks, like optimizing application performance or managing large-scale projects. Senior devs are often expected to lead teams and mentor junior developers.
I want to hire remote Java developers. What else should I consider?
When hiring remote Java developers, prioritize candidates with exceptional communication and collaboration skills. Since there’s less direct oversight when working remotely, they’ll need self-motivation and excellent time management to keep projects on track and hit deadlines.
On the technical side, make sure they have experience with remote collaboration tools like Git for version control, Slack for communication, or Jira for project management.
What should I consider when evaluating Java development services?
When evaluating Java development services, look for a track record of delivering high-performance, Java-based solutions (like we have). Make sure they’ve handled projects similar to yours, whether it’s enterprise apps, mobile apps, or cloud systems.
Does BairesDev provide dedicated Java developers?
Yes, we have hundreds of vetted Java developers on staff. Whether you need a single dedicated Java developer (staff augmentation) or an entire dedicated team (dedicated software teams), our dedicated Java developers integrate with your team, ensuring focus, continuity, and faster delivery.
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