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Scala Map filterKeys() method with example
  • Last Updated : 13 Aug, 2019

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.




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