scala默认是不可变数组，若要用变长数组，需要导入包：import scala.collection.mutable.ArrayBuffer

scala> val arr1 = new Array[Int](8)   // 用new调用的是一般类的方法，而没有使用new关键字定义的则是调用Array的静态方法

arr1: Array[Int] = Array(0, 0, 0, 0, 0, 0, 0, 0)

scala> val arr2 = new Array[String](8)

arr2: Array[String] = Array(null, null, null, null, null, null, null, null)

scala> println(arr1)

[I@489091bd

scala> println(arr1.toBuffer)    //使用toBuffer关键字可以把数组对象的内容转换成ArrayBuffer中来显示

ArrayBuffer(0, 0, 0, 0, 0, 0, 0, 0)

scala> val arr3 = Array("java","scala","python")

arr3: Array[String] = Array(java, scala, python)

scala> println(arr2(0)） // 与java不一样，遍历不用[]，使用圆括号取下标对应里面的值 

null

scala> println(arr3(0))

java

scala> val arr3 = ArrayBuffer[Int](）// 默认是不可变，若想使用可变的，则需要导入包 import scala.collection.mutable.ArrayBuffer

                  ^

       error: not found: value ArrayBuffer

scala> import scala.collection.mutable.ArrayBuffer

import scala.collection.mutable.ArrayBuffer

scala> val arr2 = ArrayBuffer[Int]()

arr2: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer()

scala> arr2 += 1

res4: arr2.type = ArrayBuffer(1)

scala> arr2 += (2,3,4)

            ^

       warning: method += in trait Growable is deprecated (since 2.13.0): Use `++=` (addAll) instead of varargs `+=`

res5: arr2.type = ArrayBuffer(1, 2, 3, 4)

scala> arr2 ++= Array(5,6)

res6: arr2.type = ArrayBuffer(1, 2, 3, 4, 5, 6)

scala> arr2 ++= ArrayBuffer(7,8)

res7: arr2.type = ArrayBuffer(1, 2, 3, 4, 5, 6, 7, 8)

scala> for(i <- arr2) println(i)

1

2

3

4

5

6

7

8

scala> for(i <- 0 until arr2.length) println(i)

0

1

2

3

4

5

6

7

scala> for(i <- 0 until arr2.length) println(i, arr2(i))

(0,1)

(1,2)

(2,3)

(3,4)

(4,5)

(5,6)

(6,7)

(7,8)

scala> for(i <- (0 until arr2.length).reverse) println(i, arr2(i))

(7,8)

(6,7)

(5,6)

(4,5)

(3,4)

(2,3)

(1,2)

(0,1)

scala> val res = for( i <- arr2) yield i * 10   // yield的关键字可以理解为， 将 i*10的结果放在一个集合上放入到 res中。

res: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(10, 20, 30, 40, 50, 60, 70, 80)

scala> res.sum

res15: Int = 360

scala> res.max

res16: Int = 80

scala> res.sorted

res17: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(10, 20, 30, 40, 50, 60, 70, 80)

scala> Array(3,6,1,2).sorted

res18: Array[Int] = Array(1, 2, 3, 6)