Java Program to add all the elements of tree set to another tree set

import java.util.*;
public class demo1 
{
 public static void main(String[] args)
 {
  TreeSet<String> tree_set = new TreeSet<String>();
  tree_set.add("C#");
  tree_set.add("C++");
  tree_set.add("Java");
  tree_set.add("HTML");
  tree_set.add("Perl");
  System.out.println("Tree set: " + tree_set);
  
  TreeSet<String> tree_set1 = new TreeSet<String>();
  tree_set1.add("Ruby");
  tree_set1.add("Python");
  System.out.println("Tree set1: "+tree_set1);
   
  tree_set.addAll(tree_set1);
  System.out.println("Tree set: "+tree_set);
 }
}