TreeSet addAll() method in java

import java.util.Iterator;
import java.util.TreeSet;
public class TreeSetAddAllMethodExample
{
   public static void main(String[] args)
   {
      TreeSet<Integer> ts1 = new TreeSet<Integer>();
      TreeSet<Integer> ts2 = new TreeSet<Integer>();
      // add in TreeSet ts1
      ts1.add(23);
      ts1.add(24);
      ts1.add(25);
      // add in TreeSet ts2
      ts2.add(26);
      ts2.add(27);
      ts2.add(28);
      // add ts2 to ts1
      ts1.addAll(ts2);
      // create an iterator
      Iterator<Integer> iterate = ts1.iterator();
      // displaying the Tree set data
      System.out.print("TreeSet values: ");
      while(iterate.hasNext())
      {
         System.out.print(iterate.next() + " ");
      }
   }
}