Scala笔记2

1. Array(“j.cole”,”big sean”,”kendrick”,”drake”)
Array.mkstring 加（”<“, “,” , “>”）<j.cole,big sean,kendrick,drake>
2. 数组相关操作
val a = Array(1,2,3) 不可扩容
val b = scala.collection.mutable.ArrayBuffer[Int]()
b.insert(0,0)
b.remove(0)
b += 1
b += (1,2)
b ++= Array(3,4)
for (ele <- b) {

   println(ele)

}
3.List
Nil其实就是一个空的集合
val l = List(1,2,3,4,5)
val b = scala.collection.mutable.ListBuffer[Int]()
list是由head和tail构成的
l.head = 1
l.tail = (2,3,4,5)
val l1 = 1 :: Nil –> List(1)
val l2 = 2 :: l1 –> List(2,1)
4.Map
val a = Map(“Tmac” -> 33,”tracy” ->44)
println(a)
a += (“masiwei” -> 24,”knowknow” -> 26)
println(a)
for ((key,value) <- a){

println(key + ": " + value)

}
for (key <- a.keySet) {

println(key + ": " + a.getOrElse(key,9))

}
5.