Java finding duplicate elements in array

/**
 * @author lautturi.com
 * Java example: find out duplicate elements in java array
 */
import java.util.*;

public class Lautturi {

	public static void main(String[] args) {
		int[] numArray = { 11,4,12,7,55,8,12,8,13,55,12,7 };
		Set<Integer> set = new HashSet<>();
		for (Integer num : numArray) 
		{
		     if (set.add(num) == false) 
		     {
		        // print the duplicate element
		    	 System.out.println("duplicate element found:"+num);
		     }
		}
		
	}
}

output:

duplicate element found:12
duplicate element found:8
duplicate element found:55
duplicate element found:12
duplicate element found:7