How to enable Java 12 preview features with Gradle?

java gradle groovy build.gradle java-12

Murali Krishna · Mar 30, 2019 · Viewed 8.3k times · Source

When I tried to build my Java code which has switch expressions using Gradle, it throws this error:

error: switch expressions are a preview feature and are disabled by default.

I tried running ./gradlew build --enable-preview which didn't work either.

I'm using Gradle 5.3.1.

Answer

You need to configure the JavaCompile tasks, so that Gradle passes this option to the Java compiler when compiling.

Something like this should work:

tasks.withType(JavaCompile).each {
    it.options.compilerArgs.add('--enable-preview')
}

To run the app/tests we need to add jvmArgs.

Example:

test {
    jvmArgs(['--enable-preview'])
}