Let's write a Spring Boot application in Kotlin. We'll start from scratch with an empty skeleton project and then go about building a tiny CRUD REST service. Along the way we'll cover all important Kotlin language basics & concepts, as well as more advanced topics like, for example, Kotlin & JPA support.

► Timestamps

00:00 Intro
00:22 Spring Initializr
03:44 Gradle & Kotlin
05:13 Project Structure
05:47 Main Class & Basic Kotlin Concepts
09:45 Data Classes
10:46 Var & Val
10:59 Null Safety
11:29 Default Parameter Values
12:47 Extension Functions
14:47 RestControllers
16:38 Named Parameters
17:26 Method Return Syntax
19:19 CRUD
20:18 Ternary Operator
21:43 More Kotlin Concepts (== vs equals, iterators etc)
25:26 JPA
31:37 Further Reading

► Timestamps

Kotlin Records vs Java Records : https://stackoverflow.com/a/66807237
Spring Boot Tutorial - Crash Course : https://youtu.be/QuvS_VLbGko?feature=shared
Gradle - Crash Course : https://youtu.be/gKPMKRnnbXU?feature=shared
Advanced Kotlin Techniques for Spring Developers - https://www.youtube.com/watch?v=lTPo1R0LznY

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Marco Codes

A crash course tutorial on building a Spring Boot application with Kotlin, aimed at Java developers new to Kotlin. Covers project setup via Spring Initializr with Gradle Kotlin DSL, key Kotlin concepts like data classes, extension functions, null safety, default parameters, and top-level functions. Walks through building a REST controller for a simple blog app, then replaces an in-memory list with Spring Data JPA and an H2 database. Highlights differences between Java and Kotlin in the Spring Boot context throughout.

Spring Boot & Kotlin Tutorial - Crash Course