“3 billion devices run Java.” 

If it seems like a lot, you might be surprised to learn that the figure falls short. Three billion devices — that’s what the Java Setup executable stated when you installed the Java client… in 2013. Since then, every metric suggests that the compiled-and-interpreted language has kept growing, both in devices and in users. In 2023, a whole decade after Java claimed to dwell in 3 billion devices, 85% of the world’s smartphones rely on an OS developed on Java. With GitHub estimating that, in 2023, there are 100 million developers worldwide, we can safely estimate that at least a third of them are Java developers. 

But what exactly is a Java developer?

A Java developer is a programmer with a solid understanding of Java syntax, object-oriented programming principles, and software development best practices. Java developers use various tools, libraries, and frameworks to create software solutions for different industries, even for software engineers or web developers.

Even if Steve Jobs pronounced it defunct in 2007, this extraordinary piece of tech has remained a stalwart in the world of programming languages since its debut in 1995. It is a versatile, object-oriented, and platform-independent language that can run on any device that supports the Java Virtual Machine (JVM). Because it is a compiled language, Java development requires a separate installation — hence the installation file we referred to. But because its source code is initially turned into a binary byte code, Java can be considered a compiled and interpreted language. Since Java “emulates” hardware, it can be used almost everywhere.

Thus, It’s tough to say what Java is primarily utilised for. It can be used to create server-side applications, mobile apps, and games, or to equip home appliances with basic features. Users choose it for web development, mobile development (especially for Android apps with Kotlin), desktop applications, embedded systems, and big data processing, and more. So, affirmative — Java can be used either to develop Minecraft, the most successful video game of all time, or to create a home automation system.

With all of this said, it's little wonder that Java developers are highly sought after, especially in the DACH region, where programmers are an important part of the tech landscape. Continuous surveys estimate that around one in every three developers works with Java, which means that the figure would stand at more than 300,000 developers in Germany alone. With such high demand, this article explores what it takes to become a Java developer and discusses the technical skills required for success in this exciting field.

What is Java development?

Within web development, Java is often associated with backend development since it deals with the logic, data, and functionality of an application or website. Backend development is responsible for communicating with databases, servers, APIs, and other components that are not visible to the end user. Even though some intriguing projects have tried to bring the tech to the client side of things, Java is rarely used for frontend.

Servlet, JSP, and Struts are just a few ways Java facilitates web development. These tools help develop backend logic, process data, manage database connections, and handle HTTP requests and responses. This is why many people consider Java to be a server-side language — primarily a backend tool.

Here's a table outlining some common tools used in Java development:

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What does a Java developer do?

Java developers can be software engineers, mobile developers, or backend developers. A Java developer will craft the server-side logic for web applications, especially in the web development realm. The core of the Java platform is the Java Virtual Machine (JVM), a component that many backend developers rein in to build up scalable and high-performance applications that can either allow you to create a sandbox game made of blocks or combine PDF files.

With almost thirty years out there, Java stands out with a robust ecosystem teeming with libraries and frameworks which streamline the development process. Here are some key aspects of backend development with Java:

• The Use of Frameworks: Spring, Play, and Struts are among the well-liked frameworks that provide pre-made modules and components. These handle various tasks such as managing databases, ensuring security, and developing REST APIs.
• Employing Integrated Development Environments (IDEs): Tools like Eclipse, IntelliJ IDEA, and NetBeans are regularly used to augment the development process. IDEs are packed with features such as code completion, debugging, and testing, making the development process more efficient and reducing the margin for errors.
• Utilising Specialised Build Tools: Maven and Gradle are examples of tools used to handle dependencies, execute tests, and generate executable files for deployment.

The role of a Java backend developer extends to creating and linking different layers, including the web server, application server, and database. This includes using web technologies such as Java Server Pages (JSP), Servlets, and Java Server Faces (JSF) to generate dynamic content and foster interactive user interfaces.

Java developers are entrusted with ensuring their applications are secure, scalable, and meet their client requirements. This includes:

• Database Management: Being well-versed in best practices for handling databases.
• Caching and Load Balancing: Understanding these processes for optimal application performance. Some examples of tools that help 

here's a table with some tools Java developers can use for Database Management, and Caching and Load Balancing:

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So, when you read how you need to load balance and work with APIs, you start thinking that Java development is more focused on infrastructure programming than frontend development and colour palettes, you’re not incorrect.

What are some of the specific tasks that a Java Developer may be responsible for?

Java can indeed be used for almost anything, but, for the sake of offering a detailed answer, we’ll stick to backend development. Backend development with Java involves creating and managing server-side applications and services that power web and mobile applications.

Here are some specific tasks that a Java backend developer may be responsible for on a given day at work:

Developing or Integrating APIs

Java's rich ecosystem of libraries and tools helps developers create flexible and scalable APIs, enabling different parts of an application to communicate seamlessly. RESTful APIs and WebSockets are some popular Java-based technologies used for API development. The whole microservices buzz made frameworks such as Spring Boot very popular.

Managing databases

A key task for backend developers is designing and implementing database structures that hold application data securely, while ensuring they perform efficiently. Java-based technologies such as Java Persistence API (JPA) and Hibernate simplify the development process and make it easy to manage different database systems.

Writing server-side code

Java's versatility allows developers to use it to create custom server-side solutions for processing and managing data using popular application servers such as Apache Tomcat and Jetty.

Monitoring system performance

Backend developers must ensure that servers are running efficiently and troubleshoot issues as they arise to provide users with seamless experiences. They often use tools like Java Management Extensions (JMX) to monitor system performance and make necessary adjustments.

Collaborating with frontend developers

Working in tandem with frontend developers, Java backend developers need to communicate effectively and work collaboratively to create applications that have both functional and aesthetic appeal. Don’t get mad if they start rambling about Figma.

Developing security protocols

Protecting user data from unauthorised access is an ongoing challenge that Java backend developers must face up. They use secure programming techniques, such as cryptographic algorithms offered by the Java Cryptography Extension (JCE) library, to encrypt sensitive data.

The following is a summary of the tasks:

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In summary, Java backend development involves a range of specialised tasks that require technical expertise and knowledge of the Java ecosystem. It’s true that many of the tasks overlap with those of backend developers — but that’s because Java can be used for backend.

Is Java good for frontend development?

As we mentioned before, Java is mostly a server-side language. But we also explored how it can be used almost for everything. As such, certain projects have helped programmers create UIs in Java. For example, Vaadin is designed to make creating and maintaining high-quality web-based user interfaces easy.

So yes, Java can be employed for frontend development. However, it's important to note that for web frontend development, technologies such as JavaScript, HTML, and CSS — the archetypal frontend kit — are more commonly used due to their lightweight nature and extensive browser support. Java tends to be more prevalent in building the user interface for desktop or enterprise applications.

What are the skills needed as a Java developer?

To excel as a Java developer, having a solid grip on the Java programming language is a given. However, one must also have extensive knowledge of popular Java frameworks and libraries and be proficient in database management. Understanding Java-based tools for development and testing is also crucial. Additionally, familiarity with web technologies such as RESTful APIs is highly influential in developing robust and scalable backend solutions.

The tech has some difficulties that will bang on the door of programmers who’re used to frontend languages. Java developers do often grapple with issues like memory management, code verbosity, and handling multi-threading effectively. Memory management in Java is primarily managed by the JVM, but poorly managed code can still result in memory leaks. Java's syntax can also be more verbose than other languages, resulting in larger and more complex codebases. Additionally, multi-threading can be a complex topic, and inexperienced developers may struggle with issues such as race conditions and deadlocks. Java Concurrency in Practice is a highly regarded book that covers this topic in depth.

The table below summarises some essential technical skills required to become a proficient Java developer:

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In addition to technical skills, staying abreast of new developments in the Java ecosystem is just as significant. Java is old enough to make people roll their eyes, but still relevant enough to get a slew of new features now and then.

Java Jargon

Java developers, like other software professionals, need to understand a host of technical terms and jargon. However, there are some specific terms that are central to Java development. Familiarity with these will boost your proficiency and help you effectively communicate with team members and stakeholders.

RESTful APIs (Representational State Transfer APIs) are a set of conventions for designing networked applications. They allow different software systems to communicate with each other, using HTTP methods to operate on resources represented in formats such as JSON or XML. In Java, JAX-RS (Java API for RESTful Web Services) is often used to create RESTful web services.

JDK (Java Development Kit) is a software development environment that includes everything you need to develop Java applications, including the Java Runtime Environment (JRE), an interpreter/loader (java), a compiler (javac), an archiver (jar), and documentation generator (javadoc) among other tools.

JRE (Java Runtime Environment) is a part of JDK, which provides the minimum requirements for executing a Java application, including the Java Virtual Machine (JVM), core classes, and supporting libraries.

JVM (Java Virtual Machine) is an abstract computing machine enabling a computer to run a Java program. It converts Java bytecode into machine language, making Java a platform-independent language.

Servlets are used to create web applications in Java. They are server-side Java programs that handle client requests and return a response.

JSP (Java Server Pages) is a technology used to create dynamic content for web pages. It is essentially a server-side scripting language for Java.

JDBC (Java Database Connectivity) is a Java API that connects a database with a range of Java applications.

JPA (Java Persistence API) is a Java specification for accessing, persisting, and managing data between Java objects and a relational database.

You can also check our backend developer jargon list for more items.

Similarly, some tools will get name-dropped frequently (including in this guide). For your convenience, you should learn what each stands for:

Spring Framework is a comprehensive framework for developing Java applications. It provides infrastructure support, so developers can focus on application development instead of routine system-level processes.

Hibernate is a Java framework used for developing object-relational mapping and data access layers in applications.

Maven and Gradle are powerful build automation tools used in Java projects for managing dependencies, compiling source code, running tests, and packaging the code for deployment.

Understanding these terms will allow Java developers to navigate through the development process smoothly, enabling them to build efficient, robust, and scalable applications. You can also ask better Stack Overflow questions with them at hand.

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How to become a Java developer?

To start to learn the Java programming language, you should start with the basics, including its syntax, object-oriented programming (OOP) concepts, and control structures. Various online courses and resources are available to help you gain a strong foundation in Java.

You should also familiarise yourself with the Java Development Kit (JDK), the Java Runtime Environment (JRE), and the Java Virtual Machine (JVM). These are essential tools for Java development. Furthermore, learn how to work with databases using Java. JDBC (Java Database Connectivity) and JPA (Java Persistence API) are among the essential tools you need to know.

Besides technology, you should consider practice, including:

• Hands-on experience: Start building your own projects as soon as possible. Practical experience is invaluable and is often more impressive to potential employers than just academic qualifications. Check out the best open source projects for beginners and you’ll soon find that Java has much to offer.
• Constant learning: The world of Java continually evolves with updates, new libraries, and frameworks. Regularly update your knowledge to stay relevant.

Remember, while a formal education in computer science or a related field can be beneficial, many successful Java developers have taken alternative educational paths: Markus Persson, better known as Notch, created Minecraft without a related degree. Online courses, coding boot camps, or hands-on experience can provide a solid foundation in Java development. So, be persistent, keep learning, and soon, you might find yourself amid a 2.5-billion-dollar deal.

However, most employers require applicants to have a degree in computer science, information systems, mathematics, or any other related field. Computer science degrees tend to be preferred as they include courses related to Java programming, including data structures, computer architecture, database management, statistics, and technical writing. We recommend Java developers to have a professional certification in Java development. 

Applicants without any degree or education can still be considered if they can show significant knowledge and programming experience in Java.

Java developer salary in 2023

According to Stack Overflow, the average Java salary worldwide in 2022 was almost €58,000 a year. In Germany, in 2023, the salary was above €60,000. Salaries might depend on experience and on if you’re a senior developer or not yet. These salaries reflect the senior role.

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This 2021 obtained from Glassdoor is an average and might not exactly reflect a salary from an acquaintance.

According to 2021 data, experience effectively impacts salaries in Germany.

Java developer jobs

There are plenty of openings for Java and Java-related jobs. Germany, Austria, and Switzerland offer a plethora of fantastic career prospects. We've partnered with Europe's most innovative tech companies to help them find brilliant Java developers like yourself. Stop wasting time with fruitless job searches and use our job board instead.

If you’d like to learn more about software development roles, check out our lexicon series, including our walkthrough What is a Backend Developer? A Complete Guide.

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