Scala学习记录（一）

 1 import scala.collection.mutable.ArrayBuffer
  2 val a = new Array[String](10)
  3 val s = Array("Hello","World")
  4 val b = ArrayBuffer[Int]()
  5
  6 b+=1
  7 b+=2
  8 b+=3
  9 println(b)
 10
 11 //immutable Map
 12 val scores = Map("Alice" -> 10, "Bob" -> 3)
 13 //can access element of Map by two ways
 14 println(scores{"Alice"})

 15 println(scores("Alice"))

 16 //can not insert new element
 17 //scores{"good"} = 4
 18
 19 //mutable Map
 20 val mscores = scala.collection.mutable.Map("Alice" -> 10, "Bob"-> 3)
 21 println(mscores{"Bob"})
 22 mscores{"good"} = 5
 23 println(mscores{"good"})
 24
 25 for((k,v) <- mscores)
 26     println(k+" "+ v)
 27 println(mscores)
 28
 29 //exchange key and value
 30 val mscores2 = for((k,v) <- mscores) yield (v,k)
 31 println(mscores2)
 32
 33 //SortedMap, default Map is hash map, you can generate Tree Map
 34 val sorted_scores = scala.collection.immutable.SortedMap("Alice" -> 10,"Fred" -> 7, "Bob" -> 3, "Cindy" -> 8)
 35 println(sorted_scores)