Iterator

An iterator is a way to access elements of a collection one-by-one. It resembles to a collection in terms of syntax but works differently in terms of functionality. An iterator defined for any collection does not load the entire collection into the memory but loads elements one after the other. Therefore, iterators are useful when the data is too large for the memory. To access elements we can make use of hasNext() to check if there are elements available and next() to print the next element.

object demo {
  def main(args: Array[String]) {
    val v = Iterator(5, 1, 2, 3, 6, 4)
    while(v.hasNext)
      println(v.next)
    }
}

Examples

object demo {
  def main(args: Array[String]) {
    //val v = Array(5,1,2,3,6,4)
    val v = List(5,1,2,3,6,4)
    // defining an iterator
    // for a collection
    val i = v.iterator
    while (i.hasNext)
      print(i.next + " ")
  }
}

// defining iterator 

val i = Iterator(5, 1, 2, 3, 6, 4) 

/* 

OR 

val v = List(5, 1, 2, 3, 6, 4) 

val i = v.iterator 

*/

// accessing elements using while loop 

while (i.hasNext) 

println(i.next) 

// defining iterator 

val i = Iterator(5, 1, 2, 3, 6, 4) 

/* 

OR 

val v = List(5, 1, 2, 3, 6, 4) 

val i = v.iterator 

*/

// accessing elements using foreach 

i foreach println 

// same as i.foreach(println)

// defining iterator 

val i = Iterator(5, 1, 2, 3, 6, 4) 

/* 

OR 

val v = List(5, 1, 2, 3, 6, 4) 

val i = v.iterator 

*/

// accessing elements using for loop 

for(k <- i) println(k) 

// defining iterator 

val i1 = Iterator(5, 1, 2, 3, 6, 4) 

// calling max function 

println("Maximum: "+ i1.max) 

// redefining iterator 

val i2 = Iterator(5, 1, 2, 3, 6, 4) 

// calling min function 

println("Minimum: "+ i2.min)