Application Plugin

It’s core plugin that give you the follow useful features:

• Adds a run task to a project
  • run task automatically executes the configured main class
• Automatically applies the java plugin
• Doesn’t create a jar file

Note that, application plugin classpath it uses is generated from the resolvable runtimeClasspath dependency configuration

runtimeClasspath is based on any implementation and runtimeOnly dependencies

Running Application

To automatically run application, it needs to apply the application plugin by replacing java plugin with application

Then will see run task through ./gradlew tasks

before run task, it needs to configure the main class to be executed

In my playground’s build script, I configured it as follows:

application {
    mainClass.set("com.gradle.theme_park.status.RideStatusService")
}

Now, run application by passing program arguments

./gradlew app:run --args logflume

JavaExec Task Class

run task is based on JavaExec task class which handles running a java process

so it can make custom run task such as that run jar file with gradle

my custom run task:

tasks.register<JavaExec>("runJar") {
    group = "application"
    description = "Run the jar file itself by gradle"

    classpath(tasks.named("jar").map { it.outputs })
    classpath(configurations.runtimeClasspath)
    args("    teacups    ")

    mainClass.set("com.gradle.theme_park.status.RideStatusService")
}

JavaExec task class provide relevant configuration

• classpath() : The classpath for the main class
• args() : The arguments passed to the main class to be executed
• mainClass : configure execution main class which runs the main method in runtime

The first classpath() is references to get the jar file created by Jar task

map() is returned by TaskProvider. This takes a lambda from which we can return anything we want from the underlying task - it.outputs

The outputs of jar task are the jar file. So the jar file get added to the classpath of the runJar task

And second is add runtimeClasspath to classpath because our application reference 3rd-party libraries

The jar file only contains our application code, so we need add other dependencies to classpath