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)

OOP in Scala


Similar to Java, the Scala compiler requires code to be wrapped inside a class. The interactive Scala REPL shell works around this limitation by automatically wrapping the entered code in an invisible class that is generated under the hood. When using the scala command, you can immediately start writing functions or code that must be executed, like you would do in a typical Python or different script language. We will cover the following topics:

  • Defining packages and subpackages
  • Importing members
  • Defining classes
  • Instance methods and variables
  • Constructors
  • Extending a class
  • Overloading methods
  • Abstract classes
  • Traits
  • Singleton objects
  • Operator overloading
  • Case classes

Defining packages and subpackages

Scala has a package statement. It can be defined at the top of a file:

    package PACKAGENAME

This form works in the same way as Java. Every class that is defined in the same source file is placed inside the PACKAGENAME package.

Scala offers more control, though. As we will soon see in a more...