TreeSet Class in Java with Example

Earlier we have discussed HashSet, LinkedHashSet class. In this tutorial we will learn about TreeSet class.

TreeSet Class:-

- Contains only unique elements.

- TreeSet implements the NavigableSet interface.

- It maintains the ascending order of inserted elements.

Syntax:-

TreeSet <E> ts = new TreeSet <E>();

E: It is the generic type of individual object.

Sample Program of TreeSet:-

import java.util.TreeSet;

public class TreeSetDemo {

     

      public static void main(String[] args) {

           

           

            TreeSet <String> ts = new TreeSet <String>();

           

            ts.add("Ravi");

            ts.add("John");

            ts.add("Joe");

            ts.add("Elly");

            ts.add("John");

           

            System.out.println(ts);

           

      }

}

Output:

[Elly, Joe, John, Ravi]

Note:-  John is duplicate inserted but TreeSet always accept unique elements.

Synchronized TreeSet:-

In actual way, TreeSet is not synchronized but we make it synchronize by using Collections.synchronizedSet() method.

TreeSet ts = new TreeSet();

Set synts = Collections.synchronizedSet(ts);