JVM Targets

Skotch can produce JVM class files, packaged JARs, DEX bytecode, and unsigned APKs. This guide covers project-level builds for each.

JVM: producing a JAR

Project structure

myapp/
  build.gradle.kts
  src/main/kotlin/
    Main.kt
    Utils.kt

`build.gradle.kts`

plugins {
    kotlin("jvm")
    application
}

group = "com.example"
version = "1.0.0"

application {
    mainClass.set("MainKt")
}

Build and run

cd myapp
skotch build
java -jar build/example.jar

The JAR includes a META-INF/MANIFEST.MF with the Main-Class header, so java -jar works directly.

Multi-module JVM projects

For projects with library modules:

myapp/
  settings.gradle.kts
  app/
    build.gradle.kts
    src/main/kotlin/Main.kt
  lib/
    build.gradle.kts
    src/main/kotlin/Helper.kt

settings.gradle.kts:

rootProject.name = "myapp"
include(":app", ":lib")

app/build.gradle.kts:

plugins {
    kotlin("jvm")
    application
}

dependencies {
    implementation(project(":lib"))
}

application {
    mainClass.set("MainKt")
}

Skotch compiles :lib first, then :app, and merges all class files into the final JAR.

skotch build -C myapp

Android: producing an APK

Project structure

myapp/
  build.gradle.kts
  src/main/kotlin/
    MainActivity.kt

`build.gradle.kts`

plugins {
    id("com.android.application")
    kotlin("android")
}

android {
    namespace = "com.example.myapp"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.example.myapp"
        minSdk = 24
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"
    }
}

Build

skotch build

The APK contains:

AndroidManifest.xml — binary AXML generated from the build config
classes.dex — DEX bytecode compiled from your Kotlin sources
resources.arsc — included if present (optional)

Overriding the target

If your build.gradle.kts uses JVM plugins but you want to produce an APK:

skotch build --target android

Single-file compilation

For quick experiments, skotch emit compiles one file at a time without needing a project structure:

# JVM class file
skotch emit --target jvm hello.kt -o HelloKt.class
java -cp . HelloKt

# DEX file
skotch emit --target dex hello.kt -o classes.dex

# Native binary (requires clang)
skotch emit --target native hello.kt -o hello
./hello

# LLVM IR (text)
skotch emit --target llvm hello.kt -o hello.ll

# Kotlin library archive
skotch emit --target klib hello.kt -o hello.klib

APK signing

Skotch supports APK Signature Scheme v2 signing with PEM key files:

android {
    signingConfigs {
        debug {
            storeFile = "keys/debug.pem"
            storePassword = ""
            keyAlias = "debug"
            keyPassword = ""
        }
    }
}