Java TreeSet comparator() Method

The comparator() method of TreeSet class returns the comparator used for sorting the elements. If the comparator uses natural ordering for sorting, it returns null

Specified by

comparator in interface SortedSet<E> : it returns the comparator used for sorting the elements. If the comparator uses natural ordering for sorting, it returns null

Return:

It returns the comparator used for sorting the elements. It returns null in the case of natural ordering.

Example 1

import java.util.*;
public class JavaTreeSetComparatorExample1
{
  public static void main(String as[]){
  TreeSet <Integer>obj = new TreeSet<Integer>();
  TreeSet <Integer>comp = new TreeSet<Integer>();
  obj.add(2);	
  obj.add(8);
  obj.add(5);
  obj.add(1);
  obj.add(10); 
  comp= (TreeSet<Integer>) obj.comparator();
  System.out.println("TreeSet: " +comp);
  }
}

Output:

TreeSet: null

Example 2

import java.util.Comparator;
import java.util.TreeSet;
public class JavaTreeSetComparatorExample2 {
    public static void main(String a[]){
          TreeSet <String> obj = new TreeSet<String>();
  obj.add("B");	
  obj.add("b");
  obj.add("A");
  obj.add("a");
 System.out.println("TreeSet: " +obj);
    }
} 
class comp implements Comparator<String>{
    public int compare(String s1, String s2) {
        return s1.compareTo(s2);
    } 
}

Output: