1. Fixed-length array
val nums = new Array[Int](10)//10个整数的数组，所有元素初始化为0
val s = Array("hello","world")//长度为2，类型由Scala自行推断，因为给了初始值，所以不用写new
s(0) = "google" //元素的访问使用()而不是[]
2. Variable length array: array buffer
For variable length arrays, the equivalent structure in Scala isArrayBuffer
import scala.collection.mutable.ArrayBuffer
val b = ArrayBuffer[Int]()//或者不写()改用new ，此处表示一个空的数组缓冲，准备存放整数
b+=1 //使用+=在尾端添加元素
b+=(1,2,3,4,5,6) //在尾端添加多个元素，以括号包起来
b++=Array（8,12,13) //可以用++=操作符在后面追加任何集合
b.trimEnd(5) //移除最后5个元素
b.insert(2,6) //在下标2之前插入
b.insert(2,1,2,3,1,3) //在下标2前插入多个元素
b.remove(2) //移除下标为2的元素
b.remove(2,3)//移除下标2开始的3个元素
b.toArray(1,1,2) //此做法为当不确定自己要构建的Array要装多少个元素时，可以先使用ArrayBuffer，然后在转换为Array
//同理，也可以使用a.toBuffer将一个数组a转化为一个数组缓冲
Note: Inserting or removing elements at any position is not efficient
3. Traverse arrays and array buffers
Use for spirit ring to traverse array or array bufferfor(i <- 区间)
for(i<- 0 until a.length)//until类似于to，但是不包含a.length
println(s"$i:${a(i)}")//s开头，字符串可以包含表达式但不能有格式化指令，拓展：row开头不会求值转义字符
设置每一步的步长
0 until a.length by 2//得到的结果是Range(0,2,4,6,8)
If you want to start the traversal at the heavy end, set the step size to -1
0 until a.length by -1
Do not use array subscripts, directly access array elements
for(elem <- a)
println(elem)
4. Array conversion
In Scala, it is very simple to convert it in some way. These conversion operations do not modify the original array, but create a completely new array.
val a = Array(2,3,5,7,11)
val result = for(elem<-a) yield 2 *elem
You can also add guards in the loop
for(elem <-a if elem % 2 ==0) yield 2*elem
But usually another way of writing
a.filter(_ % 2==0).map(2 * _)//可以用{}代替()
As mentioned above, a new array is created. For example, if you want to modify the original array (you can use indices to get the subscript sequence of the array )
val positionToRemove = for(i<-a.indices if a(i) <0 )yields i
for(i <-positionToRemove.reverse) a.remove(i)
//另一种更好的方式是将要的元素复制到前面，然后截取指定个数的元素
5. Commonly used algorithms
max,min,sum,sorted,sortedWith(),qucikSort()
mkString("<",",",">")//分别表示前缀，分隔符，后缀
6. Interpret Scaladoc
Don't explain too much for now
7. Multidimensional array
Create an array of type Array[Array[Double]]
val matrix = Array.ofDim[Double](3,4)//三行四列
//访问元素的方式：martix(row)(column) = 42
To create an irregular array
val trangle = Array[Array[Int]](10)
for(i<-trangle.indices)
trangle(i) = new Array[Int](i+1)
8. Interoperability with Java
Java's String[] array can be passed into a method that expects Java's Object[] array, but Scala does not allow such automatic conversion.
If you want to call a method with an Object[] array, you need to manually convert the type
val a = Array("dadas","dasdad","assda","dadadas")
java.util.Arrays.binarySearch(a.asInstanceOf[Array[Object]],"breef")
This part is clear