Gradle application plugin with multiple main classes

Question

I\'m using the gradle \'application\' plugin to start my application. This works well. Now I want to add the option to start a different main class in the same project. Can I ch

Answer 1

Here's how you can generate multiple start scripts if you need to package your apps

application {
    applicationName = "myapp"
    mainClassName = "my.Main1"
}
tasks.named<CreateStartScripts>("startScripts") {
    applicationName = "myapp-main1"
}
val main2StartScripts by tasks.register("main2StartScripts", CreateStartScripts::class) {
    applicationName = "myapp-main2"
    outputDir = file("build/scripts") // By putting these scripts here, they will be picked up automatically by the installDist task
    mainClassName = "my.Main2"
    classpath = project.tasks.getAt(JavaPlugin.JAR_TASK_NAME).outputs.files.plus(project.configurations.getByName(JavaPlugin.RUNTIME_CLASSPATH_CONFIGURATION_NAME)) // I took this from ApplicationPlugin.java:129
}
tasks.named("installDist") {
    dependsOn(main2StartScripts)
}

Answer 2

From http://mrhaki.blogspot.com/2010/09/gradle-goodness-run-java-application.html

apply plugin: 'java'

task(runSimple, dependsOn: 'classes', type: JavaExec) {
   main = 'com.mrhaki.java.Simple'
   classpath = sourceSets.main.runtimeClasspath
   args 'mrhaki'
   systemProperty 'simple.message', 'Hello '
}

Clearly then what you can change:

• runSimple can be named whatever you want
• set main as appropriate
• clear out args and systemProperty if not needed

To run:

gradle runSimple

You can put as many of these as you like into your build.gradle file.

Answer 3

Use javaExec task to handle it :

task run(type: JavaExec) {
    classpath = sourceSets.main.runtimeClasspath

    if (project.hasProperty('first')){
        if (chooseMain == 'Main1'){
            main = 'application.Main1'
        } else if (chooseMain == 'second'){
            main = 'application.Main2'
        }
    } else {
        println 'please pass the main name'
    }
}

And from the command line pass your option in that way :

gradle run -PchooseMain=first

Answer 4

You can directly configure the Application Plugin with properties:

application {
    mainClassName = project.findProperty("chooseMain").toString()
}

And after in command line you can pass the name of the main class:

./gradlew run -PchooseMain=net.worcade.my.MainClass