// defined array object

     val arr0= new Array[String]()

     val arr1= Array("Hello","")

     println(arr1())

     arr1()="Hello Spark!"

     println(arr1())

     // array's length can't change,but ArrayBuffer can.

     val arr2= ArrayBuffer()

     arr2+=

     for(item <- arr2) println(item)

     arr2+=(,,,)

     println(arr2.mkString(","))

     arr2++=Array(,,)

     println(arr2.mkString(","))

     arr2.trimEnd()

     println(arr2.mkString(","))

     arr2.insert(,)

     println(arr2.mkString(","))

     arr2.insert(,,,)

     println(arr2.mkString(","))

     arr2.remove()

     println(arr2.mkString(","))

     arr2.remove(,)

     println(arr2.mkString(","))

     println(arr2.toArray.mkString(","))

 val arr3=Array(,,,,,)

     for(i<- until arr3.length) println(i+":"+arr3(i))

     for(elem<-arr3) println(elem)

     val result= for(elem<-arr3) yield *elem;

     println(result.mkString(","))

     var result0 = for(elem<-arr3 if elem%==) yield *elem;

     println(result0.mkString(","))

     println(arr3.filter(_%==).map(*_).mkString(","))

     println(arr3.sum)

     val arr4= Array(,,,,)

     val result3= scala.util.Sorting.quickSort(arr4)

     println(arr4.mkString("<",",",">"))

     val arr5=ArrayBuffer(,,,,,,)

     println(arr5.sorted.mkString(","))

     val matrix= Array.ofDim[Double](,)

     for(i<-  to ;j<-  to ) println("matrix("+i+")("+j+"):"+matrix(i)(j))

     matrix()()=

     for(i<-  to ;j<-  to ) println("matrix("+i+")("+j+"):"+matrix(i)(j))

     var triangle= new Array[Array[Int]]()

     for(i<- until(triangle.length)) triangle(i)= new Array[Int](i+)