Java add elements to TreeSet

/**
 * @author lautturi.com 
 * Java example:add/insert element to TreeSet in java
 */

import java.util.*;

public class Lautturi {

	
	public static void main(String[] args) {

		  TreeSet<Integer> treeSet = new TreeSet<>();
	        // Add new element to TreeSet using the add() method
	        treeSet.add(1);
	        treeSet.add(2);
	        treeSet.add(4);
	        System.out.println("TreeSet: " + treeSet);

	        TreeSet<Integer> newTreeSet = new TreeSet<>();
	        newTreeSet.add(7);
	        
	        // Add new elements to TreeSet using the addAll() method
	        newTreeSet.addAll(treeSet);
	        newTreeSet.add(5);
	        
	        System.out.println("New TreeSet: " + newTreeSet);
	        
	}
}

output:

TreeSet: [1, 2, 4]
New TreeSet: [1, 2, 4, 5, 7]