HashSet is sealed class. It extends immutable Set and AbstractSet trait. Hash code is used to store elements. It neither sorts the elements nor maintains insertion order . The Set interface implemented by the HashSet class, backed by a hash table . In Scala, A concrete implementation of Set semantics is known HashSet.
Syntax:

var HashsetName = HashSet(element1, element2, element3, ....)  

Operations perform with HashSet

• Initialize a HashSet : Below is the example to create or initialize HashSet.
  Example :
  
  

  
  
  

  // Scala program of Initializing HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize a HashSet")                    // Creating HashSet         val hashSet: HashSet[String] = HashSet("Geeks",                                     "GeeksForGeeks", "Author")         println(s"Elements are = $hashSet")     } }

  Output:

  Initialize a HashSet
  Elements are = Set(Geeks, Author, GeeksForGeeks)

• Check specific elements in HashSet :
  Example :
  
  

  
  
  

  // Scala program of Check specific elements in HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize a HashSet")                    // Creating HashSet         val hashSet: HashSet[String] = HashSet("Geeks",                                 "GeeksForGeeks", "Author")         println(s"Elements are = $hashSet")                    // Checking         println(s"Element Geeks = ${hashSet("Geeks")}")         println(s"Element Student = ${hashSet("Student")}")     } }

  Output:

  
  
  
  

  Initialize a HashSet
  Elements are = Set(Geeks, Author, GeeksForGeeks)
  Element Geeks = true
  Element Student = false
  

• Adding an elements in HashSet : We can add an element in HashSet by using + sign. below is the example of adding an element in HashSet.
  Example :
  
  

  
  
  

  // Scala program of adding an element in HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize a HashSet")                    // Creating HashSet         val hs: HashSet[String] = HashSet("Geeks",                             "GeeksForGeeks", "Author")         println(s"Elements are = $hs")                    // Adding an element in HashSet         val hs1: HashSet[String] = hs + "GeeksClasses"         println(s"Adding elements to HashSet = $hs1")     } }

  Output:

  Initialize a HashSet
  Elements are = Set(Geeks, Author, GeeksForGeeks)
  Adding elements to HashSet = Set(GeeksClasses, Geeks, Author, GeeksForGeeks)
  

• Adding more than one element in HashSet : We can add more than one element in HashSet by using ++ sign. below is the example of adding more than one elements in HashSet.
  Example :
  
  

  
  
  

  // Scala program of adding more elements in HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize a HashSet")                    // Creating HashSet         val hs: HashSet[String] = HashSet("Geeks",                                 "GeeksForGeeks", "Author")         println(s"Elements are = $hs")                    // Adding elements in HashSet         val hs1: HashSet[String] = hs ++ HashSet[String]("Java", "Scala")         println(s"Add more than one HashSets = $hs1")     } }

  Output:

  Initialize a HashSet
  Elements are = Set(Geeks, Author, GeeksForGeeks)
  Add more than one HashSets = Set(Scala, Geeks, Author, Java, GeeksForGeeks)
  

• Remove element in HashSet : We can remove an element in HashSet by using – sign. below is the example of removing an element in HashSet.
  Example :
  
  

  
  
  

  // Scala program of removing element in HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize a HashSet")                    // Creating HashSet         val hs: HashSet[String] = HashSet("Geeks",                                 "GeeksForGeeks", "Author")         println(s"Elements are = $hs")                    // removing elements in HashSet         val hs1: HashSet[String] = hs - "Geeks"         println(s"remove element from hashset = $hs1")     } }

  Output:

  Initialize a HashSet
  Elements are = Set(Geeks, Author, GeeksForGeeks)
  remove element from hashset = Set(Author, GeeksForGeeks)

• Find the intersection between two HashSets : We can find intersection between two HashSets by using & sign. below is the example of finding intersection between two HashSets.
  Example :
  
  

  
  
  

  // Scala program of finding the intersection between two HashSets import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          println("Initialize two HashSets")                    // Creating two HashSet         val hs: HashSet[String] = HashSet("Geeks",                             "GeeksForGeeks", "Author")         println(s"Elements of hashset1 are = $hs")                    val hs1: HashSet[String] = HashSet("Java",                                      "Geeks", "Scala")         println(s"Elements of hashset2 are = $hs1")                    // finding the intersection between two HashSets         println(s"Intersection of hashSet1 and hashSet2 = ${hs & hs1}")     } }

  Output:

  Initialize two HashSets
  Elements of hashset1  are = Set(Geeks, Author, GeeksForGeeks)
  Elements of hashset2 are = Set(Scala, Geeks, Java)
  Intersection of hashSet1 and hashSet2 = Set(Geeks)
  

• Initializing an empty HashSet :
  Example :
  
  

  
  
  

  // Scala program of  Initializing an empty HashSet import scala.collection.immutable.HashSet    // Creating object object GFG {      // Main method     def main(args:Array[String])     {          // Initializing an empty HashSet         val emptyHashSet: HashSet[String] = HashSet.empty[String]         println(s"Empty HashSet = $emptyHashSet")     } }

  Output:

  Empty HashSet = Set()

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