Scala Set is a collection of pairwise different elements of the same type. In other words, a Set is a collection that contains no duplicate elements. TreeSet implements immutable sets and keeps elements in sorted order.

Declaring TreeSet Variables

The following is the syntax for declaring an TreeSet variable.

Syntax

var z : TreeSet[String] = TreeSet("Zara","Nuha","Ayan")

Here, z is declared as an tree-set of Strings which has three members. Values can be added by using commands like the following −

Command

var myList1: TreeSet[String] = myList + "Naira";

Processing TreeSet

Below is an example program of showing how to create, initialize and process TreeSet −

Example

import scala.collection.immutable.TreeSet

object Demo {
   def main(args: Array[String]) = {
      var mySet: TreeSet[String] = TreeSet("Zara","Nuha","Ayan");
      // Add an element
      var mySet1: TreeSet[String] = mySet + "Naira";
      // Remove an element
      var mySet2: TreeSet[String] = mySet - "Nuha";
      // Create empty set
      var mySet3: TreeSet[String] = TreeSet.empty[String];
      println(mySet);
      println(mySet1);
      println(mySet2);
      println(mySet3);	  
   }
}

Save the above program in Demo.scala. The following commands are used to compile and execute this program.

Command

>scalac Demo.scala
>scala Demo

Output

TreeSet(Ayan, Nuha, Zara)
TreeSet(Ayan, Naira, Nuha, Zara)
TreeSet(Ayan, Zara)
TreeSet()