Spark开发指南

array

定长数组:

val nums = new Array[Int](10)

变长数组:

val b = new ArrayBuffer[Int] 或 ArrayBuffer[Int]()

b.+=1

b.+= (2, 3, 4)

b.++= Array(5, 6, 7, 8)

b.trimEnd(3)

b.insert(2, 3)

b.insert(2, 3, 4, 5)

b.remove(2)

b.remove(2, 4)

b.toArray

遍历

for (i <- 0 until b.length)

  println(b(i))

for (i <- (0 until b.lenght).reverse)

  println(b(i))

for (element <- b)

  println(element)

数组转换:

val a = Array(1, 2, 3, 4)

val b = for (e <- a) yield e * 2

val b = a.map(_ * 2)

val c = for (e <- a if e % 2 == 0) yield 2*e

val c = a.filter(%2==0).map(2*)

常用方法:

sum:必须是数值型类型

min

max

sorted:

  scala.util.Sorting.quickSort(a)

mkString

toString

多维数组:

创建维度不同的二维数组:

var arr = new ArrayArray[Int]; arr(0) = Array(1, 3) arr(2) = new ArrayInt

创建维度相同的数组:

var matrix = Array.ofDimInt //二行,五列

matrix(0)(1) = 2 // 访问元素使用两个圆括号

与Java互操作: