Scala Map filterKeys() method with example

The filterKeys() method is utilized to find all the pairs where the keys satisfies the given predicate.

Method Definition: def filterKeys(p: (A) => Boolean): Map[A, B]

Return Type: It returns all the “key-value” pairs of the map where, the keys satisfies the given predicate.

Example #1:

// Scala program of filterKeys()
// method

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {

        // Creating map
        val m1 = Map(5 -> "geeks", 4 -> "for", 2 -> "cs")

        // Applying filterKeys method
        val result = m1.filterKeys(_ > 2)

        // Displays output
        println(result)

    }
}

Output:

Map(5 -> geeks, 4 -> for)

Here, only two key-value pairs are returned as their keys are greater than two as per the stated predicate.
Example #2:

// Scala program of filterKeys()
// method

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {

        // Creating map
        val m1 = Map(3 -> "geeks", 1 -> "for", 2 -> "cs")

        // Applying filterKeys method
        val result = m1.filterKeys(_ > 3)

        // Displays output
        println(result)

    }
}

Output:

Map()

Here, no pair is returned as none of the keys satisfies the stated predicate.