package com.dt.scala.list
object ListBuffer_Internals {
def main(args: Array[String]) {
val list = List(1,2,3,4,5,6,7,8,9)
increment(list)
increment_MoreEffective(list)
increment_MostEffective(list)
}
def increment(list: List[Int]): List[Int] = list match {
case List() => List()
case head :: tail => head + 1 :: increment(tail)
}
def increment_MoreEffective(list: List[Int]): List[Int] = {
var result = List[Int]()
for(element <- list) result = result ::: List(element +1)
result
}
def increment_MostEffective(list: List[Int]): List[Int] = {
import scala.collection.mutable.ListBuffer
var buffer = new ListBuffer[Int]
for(element <- list) buffer += element + 1
buffer.toList
}
}
3种方法：
1. 产生了过多函数调用的堆栈
2. 产生了很多中间结果
3. 最优
信息来源于 DT大数据梦工厂，微信公众号：DT_Spark
视频地址：http://edu.51cto.com/lesson/id-71305.html