How to set up Kotlin's byte code version in Gradle project to Java 8?

Question

In Kotlin project, what is a proper Gradle script to make sure my classes will be compiled to byte code ver 52 (Java 8)?

For some reason my classes are compiled as v

Answer 1

In your build.gradle.kts:

    tasks {
        val java = "11"

        compileKotlin { 
           kotlinOptions { jvmTarget = java }
           sourceCompatibility = java
        }
    }

Or like this:

tasks {
    withType<KotlinCompile> { kotlinOptions { jvmTarget = "11" } }
}

Answer 2

Kotlin 1.0 always produces Java 6 class files. Kotlin 1.1 will support generating Java 8 class files by passing -jvm-target 1.8 to the compiler. See

https://blog.jetbrains.com/kotlin/2016/07/first-glimpse-of-kotlin-1-1-coroutines-type-aliases-and-more/

for a discussion of Java 7/8 support.

Answer 3

thx for seanf's anwser ,but if your DSL kotlin is 1.3.0:

tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile::class.java).all {
    kotlinOptions {
        jvmTarget = "1.8"
    }
}