As both a development language and an ecosystem, Java attracts more and more people every day. Because learning Java has never been so accessible—thanks to books, articles, tutorials, courses at all levels, conference talks and more than 500 Java User Groups across the globe for networking—the 12 million developers who tout Java savvy are poised to get plenty of new company, and soon.
The vast amount of resources available to Java developers comes with a downside. Knowing where to start, what to learn next, whether your skills are staying relevant and what additional skills are needed to round out your role is overwhelming.
Bringing value to this role (which will pay off for you as much as your organization!) means maintaining a solid foundation while staying flexible to the curveballs that future technologies will introduce.
As you progress through your career as a Java developer, keep these 6 essential skills in focus.
1. Java: An old language, but still mainstream
Java began to be widely used in business applications in the early 2000s. It was created for a few key reasons: simplicity, robustness and portability.
First and foremost, Java offers developers a simpler language than C++. Indeed, many key functionalities of C++ were not added to the Java language just for the sake of simplicity. Multiple inheritance is an example of this.
Second, Java exists to bring a more robust language to developers. Many hard-to-find bugs in C++ were suppressed from the Java language. By providing automatic memory management, Java (almost) suppressed memory leaks that were plaguing C and C++ applications at that time.
And third, Java serves as a portable language. Being able to develop, compile and build an application on a Windows machine and deploy it on a Linux server was a revolution in software development. Gone were the days of cross-compilation and operating systems dependent versioning.
From the beginning, Java decided to keep the feature of backward compatibility, and it still holds today. The benefit is clear: a company that invested in the development of Java software 20 years ago can still be getting interest from that investment. A Java application written and compiled in 1998 using Java 2 can still be run in a Java 12 environment without having to recompile it. No other language or platform offers this guarantee.
You can see how these foundational qualities made Java a language of choice, now used in every industry sector and every layer of every application. Database access, business logic, service publication and access, human interfaces (mobile, web and desktop): all these can be written in Java, leveraging powerful frameworks and tools. Moreover, Java is used on every platform you can think of: from the SIM card of our smartphones to the high-end servers running the cloud, including embedded and IoT devices.
A developer cannot be wrong in choosing to learn Java. 98% of the Fortune 100 are hiring Java developers, and with 51 billion Java virtual machines currently running, well-paid jobs are guaranteed for Java developers for many years to come.
2. Java 8: The new foundation
As a newcomer to the Java space, the first thing you need to know is that your starting point is Java 8. It is safe to assume that all the technical articles or books that have been written and published before March 2014 when Java 8 was released are now obsolete. The Java 8 adoption rate is greater than 80%, with the remaining 20% being Java 11. So, if your Java knowledge is older than this date, then you need an update!
This should be your first task: getting to know the Java lambda expression programming model and how it has been applied to the Collection Framework.
Among the other critical features brought by Java 8 are the Stream and Collector API, a new Date and Time API built on the well-known Joda Time API and the CompletionStage API that brings a reactive programming model to the Java Util Concurrent API.
3. Java 9: Introducing a modular system
Second only to lambda expressions, the most waited-on feature of the Java platform was the Jigsaw project, which brought a modularized JDK. Over the years the JDK became a huge monolith, impossible to break, heavy to load and requiring more and more memory to run. Jigsaw and Java 9 brought the possibility to create and distribute applications with a Java runtime environment tailored for this application, dramatically improving the load time and the memory footprint. Configuring a new application to leverage this feature is very easy, and even if refactoring an existing application may prove more tricky, Jigsaw is something you need to understand to create efficient applications.
4. Java 10 and beyond: The new release cadence
Something new happened starting with Java 9: the release model changed. Before Java 9, a major release was planned for every 3 years. This slow release rate was identified as a problem and addressed. After Java 9, we waited just 6 months until Java 10, and 6 more months for the release of Java 11.
Starting with Java 9, a new major version of Java is to be released every 6 months, packaging any feature that is ready.
With this new release rate, packaging a new version of Java becomes much easier for the OpenJDK team, and projects and innovations can benefit from that. Here are some things to look forward to that will be released in the next versions:
The Amber project brings new syntax for writing strings of characters, switch expressions and one-line methods. The ultimate goal of the Amber project is to bring pattern matching to the Java language. The first step has been delivered in Java 16 (released in March 2021) with the Records and Pattern Matching.
The Loom project will bring a new concurrent programming model to the JDK, based on fibers and continuations.
The Panama project aims at improving the connection between Java applications and libraries written in other languages, including C, making it faster, more reliable and more secure.
The Valhalla project brings improvement in the memory layout of data objects, and dramatically improves the performance of in-memory computations.
The Skara project moved the Open JDK source code on GitHub, making it even simpler to contribute to the platform.
As a learner, investing time in the Java technology is a long-term effort: new functionalities are released at a regular rate, so many new things are bound to happen. Staying competitive as a Java developer means engaging in active, continuous learning with each update.
5. Long-term support: Java 11 and Java 17
The new release cadence has already proven to be a tremendous success. The open source community is keeping up, and all the main open source frameworks are supporting each release as they are delivered, including the most popular ones: Apache Maven, Apache Tomcat, Spring Boot, Hibernate, Gradle, JUnit 5, and Mockito, just to name a few.
Every three years, starting in September 2018 with Java 11, a long-term support is released. The next one is Java 17, scheduled for September 2021. It's no surprise to see an excellent adoption rate of LTS versions of Java: 20% of the Java applications are currently running Java 11, and one can expect a similar adoption rate for 17.
This new release cadence means that a new feature is integrated faster in the JDK, giving developers the possibility to learn new things on a smoother curve, and better anticipation of what to learn for the upcoming LTS. Instead of having a massive amount of new features to learn every 3 or 4 years, you have smaller bites to digest every six months.
6. Big data, artificial intelligence, machine learning
Once you beef up your skills in the foundational aspects of Java, you can set your sights on emerging technologies and industry trends. You’ll see very quickly how your skills as a Java developer give you a competitive edge in this space.
Artificial intelligence and machine learning are about processing data in massive amounts. Bernard Traversat, VP of Software Development, Java SE Platform at Oracle, says, “One of the strong positions that Java has in the Big Data space is that all the open source Big Data stacks are either written in Java or have been written for the Java Virtual Machine.” This gives Java developers a significant advantage, since building AI or ML applications and tools in Java becomes natural.
Acquiring Java skills
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