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Set in Scala | Set-1

Last Updated : 01 Feb, 2019
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A set is a collection which only contains unique items. The uniqueness of a set are defined by the == method of the type that set holds. If you try to add a duplicate item in the set, then set quietly discard your request. Syntax: 
// Immutable set
val variable_name: Set[type] = Set(item1, item2, item3)
or
val variable_name = Set(item1, item2, item3)

// Mutable Set
var variable_name: Set[type] = Set(item1, item2, item3)
or
var variable_name = Set(item1, item2, item3)
Some Important Points about Set in Scala
  • In Scala, both mutable and immutable sets are available. Mutable set is those set in which the value of the object is change but, in the immutable set, the value of the object is not changed itself.
  • By default set in Scala are immutable.
  • In Scala, the immutable set is defined under Scala.collection.immutable._ package and mutable set are defined under Scala.collection.mutable._ package.
  • We can also define a mutable set under Scala.collection.immutable._ package as shown in the below example.
  • A Set has various methods to add, remove clear, size, etc. to enhance the usage of the set.
  • In Scala, We are allowed to create empty set. Syntax: 
    // Immutable empty set
val variable_name = Set()

// Mutable empty set
var variable_name = Set()
Example 1: Scala 
// Scala program to illustrate the 
// use of immutable set
import scala.collection.immutable._

object Main 
{
    def main(args: Array[String]) 
    {
        
        // Creating and initializing immutable sets
        val myset1: Set[String] = Set("Geeks", "GFG", 
                            "GeeksforGeeks", "Geek123")
        val myset2 = Set("C", "C#", "Java", "Scala", 
                                          "PHP", "Ruby")
        
        // Display the value of myset1
        println("Set 1:")
        println(myset1)
        
        // Display the value of myset2 using for loop
        println("\nSet 2:")
        for(myset<-myset2)
        {
            println(myset)
        }
    }
}
Output: 
Set 1:
Set(Geeks, GFG, GeeksforGeeks, Geek123)

Set 2:
Scala
C#
Ruby
PHP
C
Java
Example 2: Scala 
// Scala program to illustrate the 
// use of mutable set
import scala.collection.immutable._

object Main 
{
    def main(args: Array[String])
    {
        
        // Creating and initializing mutable sets
        var myset1: Set[String] = Set("Geeks", "GFG", 
                            "GeeksforGeeks", "Geek123")
        var myset2 = Set(10, 100, 1000, 10000, 100000)
        
        // Display the value of myset1
        println("Set 1:")
        println(myset1)
        
        // Display the value of myset2 
        // using a foreach loop
        println("\nSet 2:")
        myset2.foreach((item:Int)=>println(item))
    }
}
Output: 
Set 1:
Set(Geeks, GFG, GeeksforGeeks, Geek123)

Set 2:
10
100000
10000
1000
100
Example 3: Scala 
// Scala program to illustrate the 
// use of empty set
import scala.collection.immutable._

object Main 
{
    def main(args: Array[String]) 
    {
        
        // Creating empty sets
        val myset = Set()
        
        // Display the value of myset
        println("The empty set is:")
        println(myset)
    }
}
Output: 
The empty set is:
Set()

Sorted Set

In Set, SortedSet is used to get values from the set in sorted order. SortedSet is only work for immutable set. Example: Scala 
// Scala program to get sorted values 
// from the set
import scala.collection.immutable.SortedSet 

object Main
{
    def main(args: Array[String]) 
    {
        
        // Using SortedSet to get sorted values
        val myset: SortedSet[Int] = SortedSet(87, 0, 3, 45, 7, 56, 8,6)
        myset.foreach((items: Int)=> println(items))
    }
}
Output: 
0
3
6
7
8
45
56
87

A
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