A study note based on Spring Kotlin Documentation. The current version is 5.3.0.

1 Kotlin Support

Kotlin extensions provide the ability to extend existing classes with additional functionality. Just import the the required packages.

The reified type parameters provide better type support.

Types of Java declarations are treated specially in Kotlin and called platform types. Null-checks are relaxed for such types. latform types are non-denotable, meaning that one can not write them down explicitly in the language.

Some Spring libraries such as Spring Data provide null-safe API based on JSR-305 annotations.

The Spring Framework also takes advantage of Kotlin null-safety to determine if an HTTP parameter is required without having to explicitly define the required attribute.

Spring provides Kotlin bean definition DSL.