Here you can find the source of quickEquals(Object aThis, Object aThat)
static public Boolean quickEquals(Object aThis, Object aThat)
//package com.java2s; /*// w w w . ja v a 2 s . c o m * Copyright (c) 2002-2007 Sun Microsystems, Inc. All rights reserved. * * The Sun Project JXTA(TM) Software License * * 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 end-user documentation included with the redistribution, if any, must * include the following acknowledgment: "This product includes software * developed by Sun Microsystems, Inc. for JXTA(TM) technology." * Alternately, this acknowledgment may appear in the software itself, if * and wherever such third-party acknowledgments normally appear. * * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must * not be used to endorse or promote products derived from this software * without prior written permission. For written permission, please contact * Project JXTA at http://www.jxta.org. * * 5. Products derived from this software may not be called "JXTA", nor may * "JXTA" appear in their name, without prior written permission of Sun. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 SUN * MICROSYSTEMS OR ITS CONTRIBUTORS 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. * * JXTA is a registered trademark of Sun Microsystems, Inc. in the United * States and other countries. * * Please see the license information page at : * <http://www.jxta.org/project/www/license.html> for instructions on use of * the license in source files. * * ==================================================================== * * This software consists of voluntary contributions made by many individuals * on behalf of Project JXTA. For more information on Project JXTA, please see * http://www.jxta.org. * * This license is based on the BSD license adopted by the Apache Foundation. */ public class Main { /** Quick checks for <em>possibly</em> determining equality of two objects. <P>This method exists to make <tt>equals</tt> implementations read more legibly, and to avoid multiple <tt>return</tt> statements. <P><em>It cannot be used by itself to fully implement <tt>equals</tt>. </em> It uses <tt>==</tt> and <tt>instanceof</tt> to determine if equality can be found cheaply, without the need to examine field values in detail. It is <em>always</em> paired with some other method (usually {@link #equalsFor(Object[], Object[])}), as in the following example : <PRE> public boolean equals(Object aThat){ Boolean result = ModelUtil.quickEquals(this, aThat); <b>if ( result == null ){</b> //quick checks not sufficient to determine equality, //so a full field-by-field check is needed : This this = (This) aThat; //will not fail result = ModelUtil.equalsFor(this.getSignificantFields(), that.getSignificantFields()); } return result; } </PRE> <P>This method is unusual since it returns a <tt>Boolean</tt> that takes <em>3</em> values : <tt>true</tt>, <tt>false</tt>, and <tt>null</tt>. Here, <tt>true</tt> and <tt>false</tt> mean that a simple quick check was able to determine equality. <span class='highlight'>The <tt>null</tt> case means that the quick checks were not able to determine if the objects are equal or not, and that further field-by-field examination is necessary. The caller must always perform a check-for-null on the return value.</span> */ static public Boolean quickEquals(Object aThis, Object aThat) { Boolean result = null; if (aThis == aThat) { result = Boolean.TRUE; } else { Class<?> thisClass = aThis.getClass(); if (!thisClass.isInstance(aThat)) { result = Boolean.FALSE; } } return result; } }