Scala 学习笔记之集合(5)

import collection.mutable.Buffer

object CollectionDemo6 {
  def main(args: Array[String]): Unit = {
    //可变集合类型推导
    val nums = Buffer(1)
    for (i <- 2 to 10) nums += i
    println(nums)
    //可变集合类型定义
    val nums2 = Buffer[Int]()
    for (i <- 1 to 10) nums2 += i
    println(nums2)
    //可变转不可变集合
    println(nums2.toList)
    //不可变转可变
    val m = Map("a" -> 1, "b" -> 2)
    println(m.toBuffer)
    //newBuilder 构建可变集合，result转为不可变集合，但是构造器知道可变集合的类型。
    val ls = List.newBuilder[String]
    ls ++= List("a", "b", "c")
    println(ls.result())
  }
}

运行结果：

ArrayBuffer(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
ArrayBuffer(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
ArrayBuffer((a,1), (b,2))
List(a, b, c)