/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  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 end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * 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 THE APACHE SOFTWARE FOUNDATION 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.commons.lang;

import java.io.Serializable;
/**
 * <p>Common <code>Object</code> manipulation routines.</p>
 *
 * @author <a href="mailto:nissim@nksystems.com">Nissim Karpenstein</a>
 * @author <a href="mailto:janekdb@yahoo.co.uk">Janek Bogucki</a>
 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
 * @author Stephen Colebourne
 * @since 1.0
 * @version $Id: ObjectUtils.java,v 1.7 2003/02/02 04:12:32 bayard Exp $
 */
public class ObjectUtils {
    
    /**
     * <p>Singleton used as a <code>null</code> placeholder where
     * <code>null</code> has another meaning.</p>
     *
     * <p>For example, in a <code>HashMap</code> the
     * {@link java.util.HashMap#get(java.lang.Object)} method returns
     * <code>null</code> if the <code>Map</code> contains
     * <code>null</code> or if there is no matching key. The
     * <code>Null</code> placeholder can be used to distinguish between
     * these two cases.</p>
     *
     * <p>Another example is <code>Hashtable</code>, where <code>null</code>
     * cannot be stored.</p>
     *
     * <p>This instance is Serializable.</p>
     */
    public static final Null NULL = new Null();
    
    /**
     * <p><code>ObjectUtils</code> instances should NOT be constructed in
     * standard programming. Instead, the class should be used as
     * <code>ObjectUtils.defaultIfNull("a","b");</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean instance
     * to operate.</p>
     */
    public ObjectUtils() {
    }

    //--------------------------------------------------------------------
    
    /**
     * <p>Returns a default value if the object passed is
     * <code>null</code>.</p>
     *
     * @param object  the <code>Object</code> to test
     * @param defaultValue  the default value to return
     * @return <code>object</code> if it is not <code>null</code>, defaultValue otherwise
     */
    public static Object defaultIfNull(Object object, Object defaultValue) {
        return (object != null ? object : defaultValue);
    }

    /**
     * <p>Compares two objects for equality, where either one or both
     * objects may be <code>null</code>.</p>
     *
     * @param object1  the first object
     * @param object2  the second object
     * @return <code>true</code> if the values of both objects are the same
     */
    public static boolean equals(Object object1, Object object2) {
        if (object1 == object2) {
            return true;
        }
        if ((object1 == null) || (object2 == null)) {
            return false;
        }
        return object1.equals(object2);
    }
    
    /**
     * <p>Gets the toString that would be produced by <code>Object</code>
     * if a class did not override toString itself. <code>Null</code>
     * will return <code>null</code>.</p>
     *
     * @param object  the object to create a toString for, may be
     *  <code>null</code>
     * @return the default toString text, or <code>null</code> if
     *  <code>null</code> passed in
     */
    public static String identityToString(Object object) {
        if (object == null) {
            return null;
        }
        return new StringBuffer()
            .append(object.getClass().getName())
            .append('@')
            .append(Integer.toHexString(System.identityHashCode(object)))
            .toString();
    }

    /**
     * <p>Class used as a null placeholder where null has another meaning.</p>
     *
     * <p>For example, in a <code>HashMap</code> the
     * {@link java.util.HashMap#get(java.lang.Object)} method returns
     * <code>null</code> if the <code>Map</code> contains
     * <code>null</code> or if there is no matching key. The
     * <code>Null</code> placeholder can be used to distinguish between
     * these two cases.</p>
     *
     * <p>Another example is <code>Hashtable</code>, where <code>null</code>
     * cannot be stored.</p>
     */
    public static class Null implements Serializable {
        /**
         * Restricted constructor - singleton
         */
        private Null() {
        }
        
        /**
         * <p>Ensure singleton.</p>
         * 
         * @return the singleton value
         */
        private Object readResolve() {
            return ObjectUtils.NULL;
        }
    }
    
}

@@ -133,16 +133,21 @@
 (c) 2002
+-2003
  The Apa
@@ -3076,9 +3076,9 @@
 v 1.
-7
+8
  200
@@ -3086,26 +3086,31 @@
 /02/
-02 04:12:32 bayard
+22 20:19:16 scolebourne
  Exp
@@ -6671,16 +6671,169 @@
 zable %7B%0A
+        // declare serialization compatability with Commons Lang 1.0%0A        private static final long serialVersionUID = 7092611880189329093L;%0A        %0A
         
@@ -6902,24 +6902,16 @@
         
-private 
 Null() %7B

Use more appropriate scoping for inner class from Gary Gregory