CODEWITHSUNDEEP
kotlingradlebuildcompilationexecutable-jar
sangeetds
sangeetds

Reputation: 450

Configuring build.gradle to create executable jar file for simple kotlin projects

I'm using simple text editors to write my code in Kotlin such as this:

fun main() {
    var sc = Scanner(System.`in`)
    var a = sc.nextInt()
    var b = sc.nextInt()

    print(a + b) 
}

And I've tried simple compiling and running the code in command line by 

kotlinc hello.kt -include-runtime -d hello.jar

followed by 

java -jar hello.jar

But I don't know why recently the time to compile even the simplest of code is taking more than 5 seconds and so I decided to use Gradle for compiling and running my project. It usually takes less time to compile and run but I cannot use it for running when I want to input some values. I've tried looking for some solution but the best I could find was to give some signal to Gradle that you want to feed some input during the build but that meant chaning the build everytime for different code. So I was wondering whether I could configure my build.gradle so that it could give me jar executable file which I could run.

Here's my build.gradle file : 

buildscript {
    repositories {
        mavenCentral()
        gradlePluginPortal()
       maven { url "https://dl.bintray.com/kotlin/kotlin-eap" }
    }

    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4-M1"
    }
}

plugins {
    id 'application'
}

apply plugin: "kotlin"

repositories {
    maven { url "https://dl.bintray.com/kotlin/kotlin-eap" }
    mavenCentral()
}

dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib"
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
}

group 'sangeet'
version '1.0'


mainClassName = 'MainKt'

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

sourceSets {
  main.java.srcDirs += './'
}

defaultTasks 'run'

run {
  if (project.hasProperty('main')) {
    main(project.main.replace(".kt", "Kt").capitalize())
  }
}

Upvotes: 2

Views: 1975

Answers (1)

madhead
madhead

Reputation: 33491

You'll need to include all the dependencies of your projects (e.g. kotlin-stdlib) in a JAR file so it can be used standalone. Gradle Shadow Plugin is used for that. Just add it to your project, like:

plugins {
  id 'com.github.johnrengelman.shadow' version '5.2.0'
}

and the shadowJar will produce a fat jar with everything you need.

Upvotes: 3

Related Questions