How to Sort an Array in Scala?

How to sort a Scala Map by key

Last Updated : 13 Aug, 2019

Map is same as dictionary which holds key:value pairs. In this article, we will learn how to sort a Scala Map by key. We can sort the map by key, from low to high or high to low, using sortBy.
Syntax :

mapName.toSeq.sortBy(_._1):_*

Let’s try to understand it with better example.
Example #1:

// Scala program to sort given map by key 
import scala.collection.immutable.ListMap 
  
// Creating object  
object GfG  
{  
  
    // Main method  
    def main(args:Array[String])  
    {  
      
        // Creating a map  
        val mapIm = Map("Zash" -> 30,  
                        "Jhavesh" -> 20,  
                        "Charlie" -> 50)  
                          
        // Sort map by key 
        val res = ListMap(mapIm.toSeq.sortBy(_._1):_*) 
        println(res) 
    }  
}  

Output:

Map(Charlie -> 50, Jhavesh -> 20, Zash -> 30)

Example #2:

// Scala program to sort given map by key 
import scala.collection.immutable.ListMap 
  
// Creating object  
object GfG  
{  
  
    // Main method  
    def main(args:Array[String])  
    {  
      
        // Creating a map  
        val mapIm = Map("Zash" -> 30,  
                        "Jhavesh" -> 20,  
                        "Charlie" -> 50)  
          
        // reverse map in ascending order 
        val res = ListMap(mapIm.toSeq.sortWith(_._1 < _._1):_*) 
        println(res) 
    }  
}  

Output:

Map(Charlie -> 50, Jhavesh -> 20, Zash -> 30)

Example #3:

// Scala program to sort given map by key 
import scala.collection.immutable.ListMap 
  
// Creating object  
object GfG  
{  
  
    // Main method  
    def main(args:Array[String])  
    {  
      
        // Creating a map  
        val mapIm = Map("Zash" -> 30,  
                        "Jhavesh" -> 20,  
                        "Charlie" -> 50)  
          
        // reverse map in descending order 
        val res = ListMap(mapIm.toSeq.sortWith(_._1 > _._1):_*) 
        println(res) 
    }  
}  

Output:

Map(Zash -> 30, Jhavesh -> 20, Charlie -> 50)

How to Sort an Array in Scala?

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