new HashSet(Collection> c)
import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Set; public class Main { public static void main(String[] args) { List<String> myList = new ArrayList<String>(); myList.add("Hello"); myList.add("World"); myList.add("World"); Set<String> set = new HashSet<String>(myList); System.out.println(set); } }