Scala List

In this post, we are going to see how we can merge two lists, append/prepend an element to a list.

We have various functions available to play with Scala List.

1. ::: or ++ operator to join two lists.
2. :+ and +: operators are used for append/prepend a value to a list(This will return a new list instance)


object Scala {

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

    //With ::: operator
    val list1 = List(1, 2, 3)
    val list2 = List(4, 5, 6)

    val joinList1 = list1 ::: list2
    println("joinList1::" + joinList1)


    //With ++ operator
    val joinList2 = list1 ++ list2
    println("joinList2::" + joinList2)


    //To append a value to an existing list use :+
    val appendList = list2 :+ 7
    println("appendList::" + appendList)


    //To prepend a value to an existing list
    val prependList =  3 +: list2
    println("prependList::" + prependList)

  }

}


The output is given below,


joinList1::List(1, 2, 3, 4, 5, 6)
joinList2::List(1, 2, 3, 4, 5, 6)
appendList::List(4, 5, 6, 7)
prependList::List(3, 4, 5, 6)

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