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HashSet In Scala

  • Last Updated : 04 Jul, 2019
Geek Week

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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