Book Image

Introduction to JVM Languages

By : van der Leun
Book Image

Introduction to JVM Languages

By: van der Leun

Overview of this book

Anyone who knows software development knows about the Java Virtual Machine. The Java Virtual Machine is responsible for interpreting Java byte code and translating it into actions. In the beginning, Java was the only programming language used for the JVM. But increasing complexity of the language and the remarkable performance of the JVM created an opening for a new generation of programming languages. If you want to build a strong foundation with the Java Virtual Machine and get started with popular modern programming languages, then this book is for you. The book will begin with a general introduction of the JVM and its features, which are common to the JVM languages, helping you get abreast with its concepts. It will then dive into explaining languages such as Java, Scala, Clojure, Kotlin, and Groovy and will show how to work with each language, their features, use cases, and pros and cons. By writing example projects in those languages and focusing on each language’s strong points, it will help you find the programming language that is most appropriate for your particular needs. By the end of the book, you will have written multiple programs that run on the Java Virtual Machine and know about the differences between the various languages.
Table of Contents (15 chapters)

Scala language syntax and rules


Scala is a less strict and verbose language than Java: semicolons are optional; even parentheses on function calls are not required when not needed (note the val b = new AddDemoFunctional line in the last example). We'll cover the following topics:

  • Statically typed language
  • Mutable and immutable variables
  • Common Scala types

Statically typed language

Like Java, Scala is a statically typed language; you'll have to declare variables before you can use them. It is also a strongly typed language. You can always specify the used types, like you would in Java code. Unlike Java, you are not always required to specify the types explicitly, though.

Types must be specified when declaring method input parameters and the method's return value. Types are not required when declaring variables inside a method or function body, because the Scala compiler usually can detect the correct types from the code.

Here's an example of this:

    var i = 10;
    var j = new java.lang.Object...