Here you can find the source of compare(Collection
static public <T extends Comparable<T>> int compare(Collection<T> a, Collection<T> b)
//package com.java2s; /**/*ww w . j a v a2 s.c om*/ * Created by IntelliJ IDEA. * User: wtchoi * Date: 3/26/12 * Time: 7:57 PM * * SwiftHand Project follows BSD License * * [The "BSD license"] * Copyright (c) 2013 The Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ import java.util.Collection; import java.util.Comparator; import java.util.Iterator; public class Main { static public <T extends Comparable<T>> int compare(Collection<T> a, Collection<T> b) { int temp1 = a.size(); int temp2 = b.size(); if (temp1 > temp2) return 1; if (temp1 < temp2) return -1; Iterator<T> it1 = a.iterator(); Iterator<T> it2 = b.iterator(); //assumption : two collection have equivalent sie while (it1.hasNext()) { T t1 = it1.next(); T t2 = it2.next(); int temp = t1.compareTo(t2); if (temp != 0) return temp; } return 0; } static public <T> int compare(Collection<T> a, Collection<T> b, Comparator<T> comparator) { int temp1 = a.size(); int temp2 = b.size(); if (temp1 > temp2) return 1; if (temp1 < temp2) return -1; Iterator<T> it1 = a.iterator(); Iterator<T> it2 = b.iterator(); while (it1.hasNext()) { T t1 = it1.next(); T t2 = it2.next(); int temp = comparator.compare(t1, t2); if (temp != 0) return temp; } return 0; } }