Scala--数组相关操作

val nums = new Array[Int](10)  //长度为10的int数组 初始化为0
val strs = new Array[String](10) //长度为10的String数组 初始化为null
val s = Array("Hello", "World") //初始化数组长度为2，不需要new
s(0) = "GoodBye"  //访问数组元素通过()
println(nums(0))
println(strs(0))
println(s(0)+" "+s(1))

0
null
GoodBye World

import scala.collection.mutable.ArrayBuffer

val b = ArrayBuffer[Int]()

b+=1
  //在尾端添加元素
  //ArrayBuffer(1)
b+=(2,3,4,5)
  //在尾端添加多个元素
  //ArrayBuffer(1,2,3,4,5)
b++=ArrayBuffer(8,19,20)
  //可以使用++-操作符追加任意集合
  //ArrayBuffer(1,2,3,4,5,8,19,20)
b.trimEnd(3)
  //在尾部删除3个元素
  //ArrayBuffer(1,2,3,4,5)
b.insert(2,6)
  //在下标2之前插入6
  //ArrayBuffer(1,2,6,3,4,5)
b.insert(3,7,8,9)
  //在下标3之前插入7,8,9
  //ArrayBuffer(1,2,6,7,8,9,3,4,5)
b.remove(2)
  //删除下标为2的元素
  //ArrayBuffer(1,2,7,8,9,3,4,5)
b.remove(2,3)
  //从下标为2的元素开始，删除3个元素
  //ArrayBuffer(1,2,3,4,5)

val c = b.toArray //不知道元素个数先构建ArrayBuffer，然后再转化成数组
println(c(0))
println(c.toBuffer) //数组转化成数组缓冲

1
ArrayBuffer(1, 2, 3, 4, 5)

for(i<- 0 until b.length) print(c(i)) //直接通过下标访问数组，until 不包括上线
println()
for(i<- 0 until (b.length,2))  print(b(i)) //step = 2 步长为2
println()
for(i<- (0 until b.length).reverse)  print(b(i)) //反转
println()
for(i<- b) print(i) //不使用数组下标直接访问元素
println()

　12345
  135
  54321
  12345

val a = Array(2,3,5,7,11)
val b = for(i<- a if i%2 !=0)  yield i * 2 //生成一个新的数组
for(i<- b) print(i+" ")

6 10 14 22

import scala.util.Sorting.quickSort
val a = Array(2,9,5,7,11)

println(a.sum)
println(a.max)
quickSort(a)
println(a.toBuffer)
println(a.mkString(" and "))
println(a.mkString("<"," and ",">"))
println(a.toString)
println(a.toBuffer.toString())    

34
11
ArrayBuffer(2, 5, 7, 9, 11)
2 and 5 and 7 and 9 and 11
<2 and 5 and 7 and 9 and 11>
[I@28acaa28
ArrayBuffer(2, 5, 7, 9, 11)