函数的应用

filter函数

object base44 {
  def main(args: Array[String]): Unit = {
    val arr=Array(1, 2, 3, 4,5)
    val arr1=arr.filter(x=>x%2==0)
    arr1.foreach(println)
  }
}

reduce函数

object base45 {
  def main(args: Array[String]): Unit = {
    var arr = Array(1, 2, 3, 4, 5)
    var sum = arr.reduce((x,y)=> x + y)
    println(sum)
  }
}

求最大值，最小值

object base46 {
  def main(args: Array[String]): Unit = {
    var arr = Array(-1, 20, 30, 14)
    val max = arr.reduce((x ,y) => if (x > y) x else y)
    println(max)
    val min = arr.reduce((x , y) => if (x < y) x else y)
    println(min)
  }
}

fold函数

object base47 {
  def main(args: Array[String]): Unit = {
    var arr = Array(1, 2, 3)
    val sum = arr.reduce((x ,y) => x + y )
    val sum1 = arr.fold(100) ((x ,y)=>x +y) // 106
    println(sum1)
  }
}

排序

object base48 {
  def main(args: Array[String]): Unit = {
    var arr = Array(-1, 20, 3, 2, 50)
    var arr1 = arr.sorted 
    var arr2 = Array("banana", "zip", "b", "a", "apple")
    var arr3 = arr2.sorted 
    arr3.foreach(println)
  }
}