How to use TreeSet in Java with example ?.

Program to demonstrate how to implement TreeSet class in java.util.*; package along with its operations :

package com.hubberspot.collections.example;

import java.util.*;

public class TreeSetExample
{
  public static void main(String[] args)
{
    TreeSet treeSet = new TreeSet();
    
    treeSet.add("d");
    treeSet.add("a");
    treeSet.add("s");
    treeSet.add("f");
    treeSet.add("k");
    
    System.out.println("The contents of set : "
       + treeSet);  

    System.out.println("The size of set : "
       + treeSet.size());
    
    SortedSet sortedSet = treeSet.headSet("d");

    System.out.println("The elements < d are : "
       + sortedSet);

    sortedSet = treeSet.tailSet("d");

    System.out.println("The elements > d are : "
       + sortedSet);

    sortedSet = treeSet.subSet("c", "s");

    System.out.println("The elements > d are : "
       + sortedSet);
    
 } 
}

Output of the program :