Quickstart

Tapmoc helps you configure your Java/Kotlin compatibility flags:

tapmoc {
  java(17) // build for Java 17, including source, target and api compatibility
  kotlin("2.1.0") // build for kotlin 2.1.0, including language and api version
}

Rationale

Configuring Java/Kotlin compatibility flags is a mundane task that comes with surprising amounts of questions:

• What is the difference between sourceCompatibility and targetCompatibility?
• Should I use release instead?
• What does release even mean on Android?
• Why do I need to configure Java compatibility if I only do Kotlin?
• How do I configure release with Kotlin?
• Should I use tasks.withType<KotlinCompile> or compilerOptions {} or something else?
• Is it “1.8” or “8” or JavaVersion.VERSION_1_8?
• Is it org.jetbrains.kotlin.gradle.dsl.KotlinVersion or kotlin.KotlinVersion?
• Is this working with KMP?
• And more (watch the KotlinConf 2025 talk)…

Tapmoc handles all of that with just two simple functions!

Note

The KMP ecosystem is a lot less mature than the JVM ecosystem and non-JVM targets do not support apiVersion/languageVersion. Compatibility flags only work for JVM targets.

Usage

plugins {
  // Add your Java/Kotlin/Android plugins here
  id("java")
  // or
  id("org.jetbrains.kotlin.jvm")
  // or
  id("org.jetbrains.kotlin.multiplatform")
  id("com.android.kotlin.multiplatform.library")
  // or
  id("com.android.library")
  // etc...
  // And add the Tapmoc plugin
  id("com.gradleup.tapmoc").version("0.4.0")
}

/*
 * Configure your Java/Kotlin targets with a single code block.
 */
tapmoc {
  // Java takes an int for simplicity
  java(17)
  // Kotlin takes a string so you have more control of the patch release.
  // languageVersion/apiVersion are configured with the minor version only.
  kotlin("2.1.0")

  // Optional: fail the build if any api dependency exposes incompatible Kotlin
  // metadata, Kotlin stdlib or Java bytecode version.
  checkDependencies()
}

Checking transitive dependencies

Enforcing compiler flags works for your own code but doesn’t check your dependencies. They may use incompatible APIs that will crash at runtime and/or produce incompatible metadata that will crash at build time.

You can have tapmoc fail in such cases with checkDependencies:

tapmoc {
  // Fail the build if any api dependency exposes incompatible Kotlin metadata,
  // Kotlin stdlib or Java bytecode version.
  checkDependencies()
}

Requirements

• Gradle 8.3+
• For Kotlin: Kotlin Gradle Plugin 1.9.0+
• For Android: Android Gradle Plugin 8.2.0+