import java.io.FileInputStream
import java.util.zip.ZipInputStream

object Klusek {
  val zip = new ZipInputStream(new FileInputStream("/path/to/jar/file.jar"))
  val classNames = Stream.continually(zip.getNextEntry).takeWhile(_ != null)
    .filter(entry => !entry.isDirectory && entry.getName.endsWith(".class"))
    .map(entry => entry.getName.replace("/", ".").dropRight(".class".length))
}