Java tutorial
//package com.java2s; import java.util.Collection; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class Main { public static <T> Set<T> copyToLinkedHashSet(Collection<? extends T> src) { if (src.isEmpty()) { return Collections.emptySet(); } return Collections.unmodifiableSet(new LinkedHashSet<T>(src)); } }