Scala基础——容器操作

遍历foreach

list 遍历

var l = List(1,2,3,4,5)
l.foreach(i=>println(i))

map 遍历

    var m = Map("tony" -> 80, "bob" -> 90)
    m.foreach(kv => println(kv._1, kv._2))

映射map

    val l = List("hive","hadoop","spark")
    val books= l.map(s=>s.toUpperCase)
    for(x <- books){
      println(x)
    }

flatMap

    val l = List("hive","hadoop","spark")
    val books= l.flatMap(s=>s.toList)
    for(x <- books){
      println(x)
    }

过滤filter

    val l = List(1,2,3,4,5)
    val result= l.filter(_%2==0)
    println(result)

find

    val l = List("hive","hadoop","spark")
    val result= l.find(_ startsWith "h")
    println(result)

exists

val l = List("hive","hadoop","spark")
val result= l.exists(_ startsWith "h")

reduce

    val l = List(1,2,3,4,5)
    val result= l.reduce(_+_)
    println(result)

reduceLeft

 val l = List(1,2,3,4,5)
val left= l.reduceLeft(_-_)

reduceRight

    val l = List(1,2,3,4,5)
    val right= l.reduceRight(_-_)
    println(right)