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

Generic functions

Have you ever written a function for one type then had to write it again for another type? Perhaps you wrote a function that worked for strings and then had to write the same function again for integers.

To avoid such a case, functions can be generic in the types that they use. This allows a function to be written that can work with any type, rather than a specific type only. To do this, we define the type parameters in the function signature:

    fun <T> printRepeated(t: T, k: Int): Unit { 
      for (x in 0..k) { 
        println(t) 
      } 
    } 

In this example, we print the t element k number of times. You might be thinking that we could have defined this function using Any and it would still work, since println is defined to accept Any itself. That's correct! However, what you can't do with Any is ensure that multiple parameters are of...