Scala Collections - FlatMap Method

flatMap() method is method of TraversableLike trait, it takes a predicate, applies it to each element of the collection and returns a new collection of elements returned by the predicate.

Syntax

The following is the syntax of flatMap method.

def flatMap[B](f: (A) ? GenTraversableOnce[B]): TraversableOnce[B]

Here, f: (A) ? GenTraversableOnce[B] is a predicate or condition to be applied on each element of the collection. This method returns the Option element containing the matched element of iterator which satisfiles the given condition.

Usage

Below is an example program of showing how to use flatMap method −

Example

object Demo {
   def main(args: Array[String]) = {
      val list = List(1, 5, 10)
      //apply operation
      val result = list.flatMap{x => List(x,x+1)}
      //print result
      println(result)      
   }
}

Save the above program in Demo.scala. The following commands are used to compile and execute this program.

Command

\>scalac Demo.scala
\>scala Demo

Output

List(1, 2, 5, 6, 10, 11)