Introduction to Spring Applications in Kotlin

Both Kotlin and Spring are favored for their high essence and low ceremony. Programming Spring applications with Kotlin feels like a marriage made in heaven. Spring applications created using Kotlin, when compared to those created using Java, are concise and easier to maintain.

The concise and expressive nature of Kotlin is alluring. So far in this book, we’ve seen how it takes only a few lines of code to get things done in Kotlin and how each line is succinct as well. Spring predominantly favors three different languages: Java, Groovy, and Kotlin. The developers of Spring recognized the benefits of Kotlin and decided to provide superb support for programming Spring applications with Kotlin. Several Kotlin features, among them null safety and fluent, elegant DSL syntax, convinced the Spring team to recognize Kotlin as a first-class language for programming Spring applications.

This chapter assumes that you’re familiar with creating Spring and Spring Boot applications with Java. We’ll see how Spring code written using Kotlin shines in comparison with similar code written using Java.

We’ll begin with a starter Spring Boot project and develop a small RESTful service that manages a TODO list. We’ll develop this program using Kotlin, and along the way, we’ll see what the code would look like if developed in Java. That way you’ll be able to compare the familiar Java code with the concise Kotlin code, and appreciate the elegance of Kotlin in the context of Spring. Let’s get started with Spring Boot.

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