scala list

val names = List("a", b", "c")

names.map(_.toUpperCase)

names.foreach(println)

names.foreach{ name => println(name) }


# res10: List[Int] = List(1, 2, 1, 3, 4, 3, 5)  数据展开
# flatten可以把嵌套的展开
List(List(1,2),List(1,3,4),List(3,5)).flatten



# res11: List[Int] = List(2, 4, 2, 6, 8, 6, 10)
# flatMap结合了map和flatten的功能
List(List(1,2),List(1,3,4),List(3,5)).flatMap(x=>x.map(x=>x*2))


# filter
 List(1,2,3,4,5,6).filter(_%2==0)


# zip 将2个集合结合在一起
# List[(Char, Int)] = List((a,1), (b,2), (c,3))
List('a', 'b', 'c').zip(List(1, 2, 3))

#将元素和下标结合在一起
# List((2, 0),(3, 1),(4,2),(5,3))
List(2, 3, 4, 5).zipWithIndex