Scala Collections - Filter Method

filter() method is method used by List to select all elements which satisfies a given predicate.

Syntax

The following is the syntax of filter method.

def filter(p: (A) => Boolean): List[A]

Here, p: (A) => Boolean is a predicate or condition to be applied on each element of the list. This method returns the all the elements of list which satisfiles the given condition.

Usage

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

Example

object Demo {
   def main(args: Array[String]) = {
      val list = List(3, 6, 9, 4, 2)
      // print list
      println(list)
      //apply operation
      val result = list.filter(x=>{x % 3 == 0})
      //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(3, 6, 9, 4, 2)
List(3, 6, 9)