spark 期末复习

object HelloWorld {
def main(args: Array[String]): Unit = {

    var res = for (i <- 1 to 10 if i % 2 == 0) yield { //生成器，变量每一次都会被初始化

      breakable{
        if(i>=8) break
        println(i)
      }
         i
    }

  print(res)
}
}

Array：可变，元素相同类型

var arr =new Array[Int](5)
var arr2 = Array("GigData","Spark")

可以包含不同的类型。

var tuple =("BigData",1,0.1)

scala> tuple._1
res0: String = BigData

相同类型的不可变序列，scala.collection.immutable包

var strList = List("Hadoop","BigData","Spark")

val mutableList =ListBuffer(10,20,30)
  mutableList +=40 //在尾部添加40
  println(mutableList)
 mutableList.insert(0,5)
  println(mutableList)
  mutableList.remove(0)
  println(mutableList)

ListBuffer(10, 20, 30, 40)
ListBuffer(5, 10, 20, 30, 40)
ListBuffer(10, 20, 30, 40)

不可变，带索引的一个等差序列

val v =new Range(1,10,2)//第一个是起始，第二个是终止，第三个是步长
  for( i <- v){
    println(i)
  }
}

Set：不重复元素的容器

var myset =Set("Hadoop","Spark")
myset+="Scala"

var myMap = Map("1" -> "laowang", "2" -> "zhanghua")
    myMap("3") = "wahaha"
    myMap +="4"->"hehe"
println(myMap)

Map(2 -> zhanghua, 1 -> laowang, 4 -> hehe, 3 -> wahaha)

  val iter =Iterator("Hadoop","Spark","Scala")
    while (iter.hasNext){
      println(iter.next())
    }