Scala Stack +:() method with example

In Scala, scala.collection.mutable implements Stack data structure. The +: method is similar to ++ method in Stack which gives a copy of the stack with an element prepended. Note that the ending operators are right associative.

Method Definition – def +:(elem: A)

Returns – A new stack consisting of elem followed by all elements of this stack.

Example #1:

// Scala program of mutable stack +:()
// method

// Import Stack
import scala.collection.mutable._

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {
        // Creating a value
        val q1 = 1

        val q2 = Stack("for", "geeks")

        // Applying +:() method
        val result = q1 +: q2

        // Display output
        print(result)

    }
}

Output:

Stack(1, for, geeks)

Example #2:

// Scala program of mutable stack +:() method

// Import Stack
import scala.collection.mutable._

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {
        // Creating a stack
        val q1 = List(1 )

        val q2 = List(11, 12, 13, 14, 15)

        // Applying ++() method
        val result = q1.+:(q2)

        // Display output
        print(result)

    }
}

Output:

List(List(11, 12, 13, 14, 15), 1)