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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boilerplate code between the web browser and your Java code. This version 4.0.2 works with Jakarta Servlet 4.0.2.

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package org.directwebremoting.util;

/**
 * Some utilities for comparing objects that could be null
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class CompareUtil
{
    /**
     * Compare 2 objects taking account of the fact that either could be null
     * @param  The type that we are comparing
     * @param o1 The first object to compare
     * @param o2 The second object to compare
     * @return -1, 0, or 1
     */
    public static  int compare(Comparable o1, T o2)
    {
        if (o1 == null && o2 == null)
        {
            return 0;
        }

        if (o1 == null)
        {
            return -1;
        }

        if (o2 == null)
        {
            return 1;
        }

        return o1.compareTo(o2);
    }

    /**
     * Compare 2 objects taking account of the fact that either could be null
     * @param o1 The first object to compare
     * @param o2 The second object to compare
     * @return true iff they are both null or if o1.equals(o2) 
     */
    public static boolean equals(Object o1, Object o2)
    {
        if (o1 == null && o2 == null)
        {
            return true;
        }

        if (o1 == null || o2 == null)
        {
            return false;
        }

        return o1.equals(o2);
    }
}