Kotlin Example of Class and Controller

GreetingController

data class Greeting(val id: Long, val content: String)

Next, a GreetingController will be used for a get request:

@RestController
class GreetingController {

    val counter = AtomicLong()

    @GetMapping("/greeting")
    fun greeting(@RequestParam(value = "name", defaultValue = "World") name: String) =
            Greeting(counter.incrementAndGet(), "Hello, $name")

}

When creating the Application class Spring Boot looks for a public static main method. This can be defined in Kotlin using a top-level function defined outside Application class like this:

@SpringBootApplication
class Application

fun main(args: Array<String>) {
    SpringApplication.run(Application::class.java, *args)
}