Book Image

Learn Kotlin Programming - Second Edition

By : Stephen Samuel, Stefan Bocutiu
Book Image

Learn Kotlin Programming - Second Edition

By: Stephen Samuel, Stefan Bocutiu

Overview of this book

Kotlin is a general-purpose programming language used for developing cross-platform applications. Complete with a comprehensive introduction and projects covering the full set of Kotlin programming features, this book will take you through the fundamentals of Kotlin and get you up to speed in no time. Learn Kotlin Programming covers the installation, tools, and how to write basic programs in Kotlin. You'll learn how to implement object-oriented programming in Kotlin and easily reuse your program or parts of it. The book explains DSL construction, serialization, null safety aspects, and type parameterization to help you build robust apps. You'll learn how to destructure expressions and write your own. You'll then get to grips with building scalable apps by exploring advanced topics such as testing, concurrency, microservices, coroutines, and Kotlin DSL builders. Furthermore, you'll be introduced to the kotlinx.serialization framework, which is used to persist objects in JSON, Protobuf, and other formats. By the end of this book, you'll be well versed with all the new features in Kotlin and will be able to build robust applications skillfully.
Table of Contents (21 chapters)
Free Chapter
1
Section 1: Fundamental Concepts in Kotlin
5
Section 2: Practical Concepts in Kotlin
15
Section 3: Advanced Concepts in Kotlin

Varargs

Kotlin allows functions to be defined so that they would accept a variable number of arguments. Hence, this feature is called varargs. Varargs allow users to pass in a comma-separated list of arguments, which the compiler will automatically wrap into an array. Java developers will already be familiar with the feature, which, in Java, looks like the following:

    public void println(String.. args) { } 

The Kotlin equivalent is to use the vararg keyword before the parameter name:

    fun multiprint(vararg strings: String): Unit { 
      for (string in strings) 
      println(string) 
    } 

This would be invoked by simply enumerating the arguments as in the following example:

    multiprint("a", "b", "c") 

Functions can have regular parameters, and, at most, one parameter marked as vararg:

    fun multiprint(prefix: String, vararg strings:...