Here you can find the source of asSet(final T t, final T... ts)
public static <T> Set<T> asSet(final T t, final T... ts)
//package com.java2s; /*/*from w w w . j a va 2 s . c om*/ * Copyright (C) 2013 * * 52?North Initiative for Geospatial Open Source Software GmbH * Contact: Andreas Wytzisk * Martin-Luther-King-Weg 24 * 48155 Muenster, Germany * info@52north.org * * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html */ import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.Set; public class Main { public static <T> Set<T> asSet(final Iterable<? extends T> iterable) { return (iterable instanceof Collection) ? new HashSet<T>((Collection<? extends T>) iterable) : new HashSet<T>() { private static final long serialVersionUID = 3109256773218160485L; { if (iterable != null) { for (final T t : iterable) { add(t); } } } }; } public static <T> Set<T> asSet(final T t, final T... ts) { final Set<T> set = new HashSet<T>(ts.length + 1); set.add(t); Collections.addAll(set, ts); return set; } }