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

toString out of the box

When you define a new type, best practices dictate that you should provide an override for the toString method. This method should return a string describing the instance. Let's consider the BlogEntry class we defined at the beginning of this chapter. You will have to do quite a bit of typing to implement this method, but why do it when you can get it out of the box? Let the compiler do it for you. If you add or remove a new field, it will automatically update the code for you. The likelihood of you leaving out the change to the toString code body when a field is added/renamed/removed is quite high:

public java.lang.String toString();
  Code:
    0: new           #122                // class  java/lang/StringBuilder
    3: dup        
    4: invokespecial #123              // Method  java/lang/StringBuilder."<init>":()V
    7: ldc ...