1-Old.kt

// MainApp.kt
fun main() {
  val date = Date()
  val formattedDate = DateUtils.formatDate(date, "yyyy-MM-dd")
}

// DateUtils.kt
object DateUtils {
  fun formatDate(date: Date, pattern: String): String {
    return SimpleDateFormat(pattern).format(date)
  }
}

2-New.kt

// MainApp.kt
fun main() {
  val date = Date()
  val formattedDate = date.format("yyyy-MM-dd")
}

// DateExt.kt
fun Date.format(pattern: String): String = SimpleDateFormat(pattern).format(this).format(this)