Kotlin on jvm 14


I have the nex error when a I try to compile my spring boot application using kotlin, the project is using java 14

Failed to execute goal org.jetbrains.kotlin:kotlin-maven-plugin:1.3.72:compile (compile) on project X: Compilation failure
Unknown JVM target version: 14
Supported versions: 1.6, 1.8, 9, 10, 11, 12, 13

Do you know if kotlin is already supported by java 14 ?

Yes, it is.
You can use 13 on compiler without any issue.

It means, that compiler generates bytecode with this version. Java 14 can run jar with any bytecode above.
Theoretically it is better to select the largest value here, because Kotlin compiler has more options for code generation, e.g. it can generate more effective instructions.

However, as I remember, Kotlin compiler for now (e.g. for version 1.3.72) generates the same bytecode for all values 1.8 - 13.

Kotlin currently do not have any specific features for bytecode newer than 1.8. In future, there surely be new features, but right now, it is OK to set the bytecode target to 1.8 and enjoy any JDK.