Here you can find the source of toSet(Iterable
public static <T> Set<T> toSet(Iterable<T> items)
//package com.java2s; /******************************************************************************* * Copyright (C) 2015 Anton Gustafsson//from w w w.ja v a 2 s . c o m * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. ******************************************************************************/ import java.util.HashSet; import java.util.Iterator; import java.util.Set; public class Main { public static <T> Set<T> toSet(Iterable<T> items) { return toSet(items.iterator()); } public static <T> Set<T> toSet(Iterator<T> items) { Set<T> set = new HashSet<T>(); while (items.hasNext()) set.add(items.next()); return set; } }