Classes and inheritance

Kotlin, being a language that aims for strong interoperability with Java and the JVM, shares a strong affinity with the Java programming language, which is class-based. Therefore, Kotlin also supports classes and classical inheritance. In this section, we will cover the syntax to declare classes, interfaces, abstract classes, and data classes.

Classes

In Kotlin, a class is a collection of data, called properties, and methods. To declare a class, you use the keyword class, similar to in Java. For example, let’s define a class to represent a player in a video game:

class Player {
    // class members and functions
}

To create an instance of a class, you simply call the class constructor using parentheses, without the need for the new keyword:

val player = Player()

If the class doesn’t have a body or additional members, you can even omit the curly braces:

class Player // No body, still valid

However, classes without...