Where is Java used in Real World?

If you are a beginner and just started learning Java, you might be thinking about where correctly Java is used? You don't see many games written in Java except Minecraft, desktop tools like Adobe Acrobat, Microsoft Office are not written in Java, neither are your operating systems like Linux or Windows, so where exactly do people use Java? Does it have any real-world application or not? Well, you are not alone, many programmers ask this question before starting with Java, or after picking Java as one of the programming languages of choice at the graduate level.

By the way, you can get a clue of where Java is used by installing Java on your desktop, Oracle says more than 3 billion devices run Java, that's a huge number, isn't it? Most major companies use Java in one way or another.

Many server-side applications are written in Java which processes tens of millions of requests per day. High-frequency trading applications are also written in Java like LMAX trading applications, which is built over their path-breaking inter-thread communication library, Disruptor.


In this article, we will see more precisely what kind of projects are done in Java, which domain or sector Java is dominating, and where exactly Java is used in the real world? But, if you are already convinced about Java's power and reach and just want to learn Java then I suggest you join these Java Programming courses to learn Java from scratch. This includes the best and most up-to-date courses to learn Java.

Real-World Java Applications

There are many places where Java is used in the real world, starting from a commercial e-commerce website to android apps, from scientific application to financial applications like electronic trading systems, from games like Minecraft to desktop applications like Eclipse, Netbeans, and IntelliJ, from an open-source library to J2ME apps, etc. Let's see each of them in more detail.

1. Android Apps

If you want to see where Java is used, you are not too far away. Open your Android phone and any app, they are actually written in Java programming language, with Google's Android API, which is similar to JDK. 

A couple of years back, Android has provided a much-needed boost, and today many Java programmer is Android App developers. By the way, Android uses different JVM and different packaging, as we have seen in our previous article about how the Android app works, but code is still written in Java.

2. Server Apps at the Financial Services Industry

Java is very big in Financial Services. Lots of global Investment banks like Goldman Sachs, Citigroup, Barclays, Standard Charted, and other banks use Java for writing front and back office electronic trading systems, writing settlement and confirmation systems, data processing projects, and several others. 

Java is mostly used to write a server-side application, mostly without any front end, which receives data from one server (upstream), processes it, and sends it to other processes (downstream). Java Swing was also popular for creating thick client GUIs for traders, but now C# is quickly gaining market share in that space, and Swing is out of its breath.

3. Java Web applications

Java is also big in the E-commerce and web application space. You have a lot of  RESTfull services being created using Spring MVC, Struts 2.0, and similar frameworks. Even simple Servlet, JSP, and Struts-based web applications are quite popular on various government projects. Many governments, healthcare, insurance, education, defense, and several other departments have their web application built in Java.

4. Software Tools

Many useful software and development tools are written and developed in Java, like Eclipse IDE, IntelliJ Idea, and NetBeans IDE. I think they are also the most used desktop applications written in Java. 

Though there was a time when Swing was very popular to write thick clients, mostly in the financial service sector and Investment banks. Nowadays, Java FX is gaining popularity, but still, it is not a replacement for Swing, and C# has almost replaced Swing in Finance domain.

5. Trading Application

Third-party trading applications, which is also part of the bigger financial services industry, also use Java. A popular trading application like Murex, which is used in many banks for front-to-bank connectivity, is also written in Java.

6. J2ME Apps

Though the advent of iOS and Android almost killed the J2ME market, there is still a large market of low-end Nokia and Samsung handsets, which use J2ME. There was a time when almost all games, applications, which are available in Android are written using MIDP and CLDC, part of the J2ME platform. J2ME is still popular on products like Blu-ray, Cards, Set-top boxes, etc. One of the reasons for WhatsApp being so popular is because it is also available in J2ME for all those Nokia handsets which are still quite big.

7. Embedded Space

Java is also big in the embedded space. It shows how capable the platform is, you only need 130 KB to be able to use Java technology (on a smart card or sensor). Originally Java was designed for embedded devices. In fact, this is the one area, which was part of Java's initial campaign of "write once, run anywhere," and it looks like it is paying up now.

8. Big Data technologies

Hadoop and other big data technologies are also using Java in one way or another like Apache's Java-based HBase and Accumulo (open source) and  ElasticSearch as well. Java is not dominating this space, as there are technologies like MongoDB, which is written in C++. Java has the potential to get a major share of this growing space if Hadoop or ElasticSearch goes big.

9. High-Frequency Trading Space

Java platform has improved its performance characteristics a lot, and with modern JITs, its capable of delivering performance at the C++ level. Due to this reason, Java is also popular in writing high-performance systems, because Though performance is a little less compared to native language, you can compromise safety, portability, and maintainability for more speed and it only takes one inexperienced C++ programmer to make an application slow and unreliable.

10. Scientific Applications

Nowadays Java is often a default choice for scientific applications, including natural language processing. Main reason of this is because Java is more safe, portable, maintainable and comes with better high-level concurrency tools than C++ or any other language.


In the 1990s Java was quite big on the Internet due to Applet, but over the years, Applet's lost its popularity, mainly due to various security issues on Applet's sandboxing model. Today desktop Java and Applets are almost dead. 

Java is by default Software industries darling application development language, and given its heavy usage in the financial services industry, Investment banks, and E-commerce web application space, anyone learning Java has a bright future ahead of him. Java 8 has only reinforced the belief that Java will be continuing dominating software development space for years to come.