Scala深入浅出进阶经典 第82讲：Scala中List的ListBuffer是如何实现高效的遍历计算的

package com.dt.scalaInAction.demo_082

/**
* Scala中List的构造是的类型约束逆变、协变、下界详解
*/
object ListBuffer_Internals {
def main(args: Array[String]): Unit = {
val list = List(1, 2, 3, 4, 5, 6, 7, 8, 9)
println(increment(list))
println(increment_MoreEffective(list))
println(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(e <- list) result = result ::: List(e+1)
result
}

def increment_MostEffective(list: List[Int]): List[Int] = {
import scala.collection.mutable.ListBuffer
var buffer = new ListBuffer[Int]
for(e <- list) buffer += e + 1
buffer.toList
}

}

以上内容是从王家林老师DT大数据课程第82讲的学习笔记和个人整理。

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