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What are the differences between Scala and Java?

Scala is the next generation of the Java Virtual Machine (JVM). This language is becoming increasingly popular as a modern alternative to Java. Introduced back in 1995, Java was considered one of the undisputed leaders among programming languages, especially in the field of server-side programming. To date, Scala certainly can not boast of such a high level of popularity as Java. However, over the past few years, the popularity of Scala has been growing steadily.

Twitter's decision in 2019 to move its platform from Ruby to Scala has caught the attention of many companies in the web development world. Such advertising played a key role, so many other companies after that began to switch to Scala. Today, Scala is used for back-end development of many websites: eBay, Netflix, LinkedIn and The Guardian.

An increasing number of programmers are switching to Scala. Therefore, if you are involved in development, then it is important for you to understand the difference between Java and Scala in order to have enough information when working on the next project and choose the most suitable language.

Scala vs Java


Code size and quality

When using Java, developers need to write long lines of code to perform simple tasks. Scala allows you to perform the same tasks using more concise code. A task that requires 20 lines of Java code will take only 6 on Scala. This compression of the code allows you to make it more organized, as well as easy to read and use. Fewer lines also make it easier to find and fix bugs.

The functional nature of Scala allows for more natural use of lambda functions and chains, requiring less code.


Code complexity

Scala uses more complex structures than Java. Many developers note that at the initial stage, Scala is more difficult to study.

When it comes to using advanced features in the Scala language, the level of complexity is greatly increased. That's why Scala has gained a reputation as a complex language. However, for those who are starting to learn the language from scratch, the more concise Scala code can make life much easier.


Functional programming


Java was created in the 1990s, so it was formed as an object-oriented programming language. However, later it was improved and received some functional programming capabilities.

Scala was created in the early 2000s initially as a functional programming language. Unlike Java, Scala has more advanced features in functional programming, such as immutability ("untimeliness"), high-order functions, and deferred computing.



Scala borrowed much of the syntax and functions from Java. But Scala still has a number of structures that are not available in Java. For example, Scala supports case classes and automatic type inference. The high structuring of the Scala language allows programmers to further use it as a domain-specific language (DSL). This allows you to use Scala to meet the needs of specific projects.



In theory, Java and Scala are compatible with each other. Developers can call Java functions directly inside Scala code. However, the process of embedding Java functions into Scala code and vice versa is not as simple as it looks at first glance. Each language implements interfaces, collections, annotations, and other functions in its own way. Therefore, although both languages are mutually compatible, but these differences still matter.


Concurrency model

When using Java 8, programmers are forced to adhere to the classic, thread-based model of parallelism. This approach splits the program into several parallel running tasks at the execution stage. Scala uses the actor model, which is more modern and efficient. This allows developers to define each object as an actor with a specific behavior and mailing address. In this way, Scala simplifies thread interaction and control, thereby increasing the efficiency of the entire process.


According to a test conducted by it news resource DZone, Scala is 20% faster than Java. However, it is worth noting that performance evaluation is always subjective, so you should not trust it 100%.

Because both languages run on the JVM, their code must be compiled into bytecode in the same way before they can run. Scala wins performance thanks to optimization techniques such as tail call recursion, which is performed at compile time, where if the last expression in a method is a recursive call, it can be omitted and replaced with an iterative solution. In addition to this optimization, in fact, Java and Scala have similar performance characteristics, since both languages work on the JVM.

Unless you need to implement a real-time application, the difference in performance between the two languages will not be key. If your application handles network traffic, http requests, or connects to a database, then the performance impact of the language will be negligible.


Accessibility of tools and frameworks

As noted earlier, Java is a more "adult" language. Therefore, Java developers have a wider choice of editors, frameworks and tools. And this is perhaps one of the main advantages of this language. It will take years for Scala to build an equally strong community and assemble the same archive of tools.

As Scala's popularity continues to grow, new tools and frameworks are released regularly. In addition, Scala is a JVM language, so developers in this language have the opportunity to use some Java libraries and frameworks.

Java or Scala: which language to choose?

As a result, the more complex structures of Scala-code and some difficulties in learning this language are balanced by its conciseness and wide possibilities in functional programming. On the other hand, Java is an extremely common solution for many large companies around the world and continues to provide programmers with a wide range of tools and frameworks.

In general, Java and Scala have many similarities and both can be used to create a wide variety of applications. However, each of these programming languages has its own strengths and weaknesses. Therefore, when working on each project, it is necessary to assess the current needs and, based on them, decide which language to choose for development. Scala is a great option for applications that deal with big data. But for other projects, the complexity of the code and a small number of specialists can neutralize all the bonuses that Scala can provide.