objectutils.java

jworks program

package org.softme.util;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 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.
 *
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 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
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 * 5. Products derived from this software may not be called "Apache",
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 * ====================================================================
 *
 * 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/>.
 */

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.Hashtable;
import java.util.Vector;

/**
 * This is where common Object manipulation routines should go.
 *
 * @author <a href="mailto:[e-mail]">Nissim Karpenstein</a>
 * @version $Id: ObjectUtils.java,v 1.1.1.1 2004/08/20 05:57:58 brokendoor Exp $
 */
public class ObjectUtils
{
    /**
     * Returns a default value if the object passed is null.
     *
     * @param o The object to test.
     * @param dflt The default value to return.
     * @return The object o if it is not null, dflt otherwise.
     */
    public static Object isNull(Object o, Object dflt)
    {
        if (o == null)
        {
            return dflt;
        }
        else
        {
            return o;
        }
    }

    /**
     * Adds an object to a vector, making sure the object is in the
     * vector only once.
     *
     * @param v The vector.
     * @param o The object.
     */
    public static void addOnce(Vector v, Object o)
    {
        if (! v.contains( o ))
        {
            v.addElement( o );
        }
    }

    /**
     * Deserializes a single object from an array of bytes.
     *
     * @param objectData The serialized object.
     * @return The deserialized object, or <code>null</code> on failure.
     */
    public static Object deserialize(byte[] objectData)
    {
        Object object = null;
        if (objectData != null)
        {
            // These streams are closed in finally.
            ObjectInputStream in = null;
            ByteArrayInputStream bin = new ByteArrayInputStream(objectData);
            BufferedInputStream bufin = new BufferedInputStream(bin);
            try
            {
                in = new ObjectInputStream(bufin);

                // If objectData has not been initialized, an
                // exception will occur.
                object = in.readObject();
            }
            catch (Exception e)
            {
            }
            finally
            {
                try
                {
                    if (in != null)
                    {
                        in.close();
                    }
                    if (bufin != null)
                    {
                        bufin.close();
                    }
                    if (bin != null)
                    {
                        bin.close();
                    }
                }
                catch(IOException e)
                {
                }
            }
        }
        return object;
    }

    /**
     * Compares two Objects, returns true if their values are the
     * same.  It checks for null values prior to an o1.equals(o2)
     * check
     *
     * @param o1 The first object.
     * @param o2 The second object.
     * @return True if the values of both xstrings are the same.
     */
    public static boolean equals(Object o1, Object o2 )
    {
        if (o1 == null)
        {
            return (o2 == null);
        }
        else if (o2 == null)
        {
            // o1 is not null
            return false;
        }
        else
        {
            return o1.equals(o2);
        }
    }

    /**
     * Nice method for adding data to a Hashtable in such a way
     * as to not get NPE's. The point being that if the
     * value is null, Hashtable.put() will throw an exception.
     * That blows in the case of this class cause you may want to
     * essentially treat put("Not Null", null ) == put("Not Null", "")
     * We will still throw a NPE if the key is null cause that should
     * never happen.
     */
    public static final void safeAddToHashtable(Hashtable hash, Object key,
            Object value)
            throws NullPointerException
    {
        if (value == null)
        {
            hash.put(key, "");
        }
        else
        {
           hash.put(key, value);
        }
    }
}