Java tutorial
//package com.java2s; import java.util.Collections; import java.util.HashSet; import java.util.Set; public class Main { public static <E> Set<E> toSet(Iterable<? extends E> iterable) { final Set<E> set = new HashSet<E>(); for (E e : iterable) { set.add(e); } return Collections.unmodifiableSet(set); } }