Clojure renames null to nil, additionally treating it as false in boolean expressions.Groovy has similar background but adds some syntactic sugar, namely Elvis Operator ( ?:) and Safe Navigation Operator ( ?.).If it’s not a primitive, every single field, parameter or return value can be null. Java doesn’t go much further than C - every reference (“pointer”) can be null, whether you like it or not.There are at least couple of approaches to nullhandling in JVM languages:
It has some good documentation so today I will focus on a tiny part of it - null safety. We can achieve this by simply extending the Java Optional class as follows: fun Optional.toNullable(): T? = this.Kotlin is a statically typed JVM language developed by Jetbrains. Ideally this should be available on any Java Optional object (in our project only). So all I need is a simple piece of code that converts a Java Optional into a Kotlin Nullable.
They enable us to add functionality to classes that we cannot change or subclass, for example as it is final. I already knew the concept of extensions from Swift and found that Kotlin also supports extensions. Since we are implementing in Kotlin we would like to use Kotlin Nullables instead and as it turned out we can achieve this very easily. Using this API out of the box would force us to deal with cumbersome Java Optionals. This library is written in Java, hence method signatures look like this: Optional findById(ID var1) We are using a CrudRepository that provides basic functionalities like save(), delete(), findById() etc. This includes Spring Boot Jpa Repositories. We are using Kotlin and Spring Boot in one of our projects.
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