将信息从一个列表合并到另一个Scala

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)
val mergedList = list1 ++ list2

// mergedList: List(1, 2, 3, 4, 5, 6)

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)
val mergedList = list2 ::: list1

// mergedList: List(4, 5, 6, 1, 2, 3)

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)
val list3 = List(7, 8, 9)
val mergedList = List.concat(list1, list2, list3)

// mergedList: List(1, 2, 3, 4, 5, 6, 7, 8, 9)