I hate working with resources in Java or Kotlin. The idea if resources is good, but loading them is unbelievable error-prone ... every time. This one makes it a little easier. It just looks for the given file or path according to the package-path of the class.

resources.kt

import java.io.File
import kotlin.reflect.KClass

object Resources {
    /**
     * Loads a resource from within the resources-Folder (usually src/main/resources):
     * ```
     * val resource : File = this::class.resourceFile("myResource.xml")
     * ```
     */
    @Suppress("RECEIVER_NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
    fun <K : Any> file(clazz: KClass<K>, path: String): File {

        return File(clazz.java.classLoader.getResource(path).file)
    }

    fun <K : Any> lines(clazz: KClass<K>, path: String) = file(clazz, path).reader().readLines()
    fun <K : Any> content(clazz: KClass<K>, path: String) = file(clazz, path).reader().readText()
}

/**
 * Loads a resource within the package-structure of the current class. If the class full qualified-name is
 * `org.acme.ResourceLoader`, then the following code will try to load `org/acme/myResource.xml` from within the
 * resources-Folder (usually src/main/resources):
 * ```
 * val resource : File = this::class.resourceFile("myResource.xml")
 * ```
 */
fun <T : Any> KClass<T>.resourceFile(file: String) =
    Resources.file(this, this.qualifiedName?.substringBeforeLast('.')?.replace('.','/')+"/"+file)

fun <T : Any> KClass<T>.resourceContent(file: String) = resourceFile(file).reader().readText()
fun <T : Any> KClass<T>.resourceLines(file: String) = resourceFile(file).reader().readText()