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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.io;

import org.directwebremoting.util.LocalUtil;

/**
 * A SortCriterion describes one facet of a possible way of sorting some data.
 * It will generally be used as a List<SortCriterion>. So the data is
 * sorted by the fist SortCriterion in the list first, turning to the second
 * only if there is an equals scenario between 2 bits of data.
 * It is assumed that values for each attribute can be extracted from the data.
 * This is generally fairly simple for Maps and Pojos.
 * SortCriterion does not specify a {@link java.util.Comparator}. It is assumed
 * that the values stored by the data against each attribute are either
 * {@link Comparable} or that the system can find a {@link java.util.Comparator}
 * Pomposity alert:
 * I wouldn't normally be pedantic about Criteria/Criterion, but it's important
 * to note that this is just one facet of an instruction to a sorting algorithm,
 * and not the entire instruction.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class SortCriterion
{
    /**
     * All SortCriterion need an attribute and sort order.
     * @param attribute ...
     * @param descending ...
     */
    public SortCriterion(String attribute, boolean descending)
    {
        this.attribute = attribute;
        this.descending = descending;
    }

    /**
     * The attribute points to a data member within the data to be sorted.
     * If the data is a {@link java.util.Map} this will be a key. If the data
     * is a Pojo, it will be a property.
     * @return The name of the data member to sort
     */
    public String getAttribute()
    {
        return attribute;
    }

    /**
     * Are we sorting in descending order?
     * @return ...
     */
    public boolean isDescending()
    {
        return descending;
    }

    /**
     * Are we sorting in ascending order?
     * This is the logical negative of {@link #isDescending()}
     * @return ...
     */
    public boolean isAscending()
    {
        return !descending;
    }

    @Override
    public int hashCode()
    {
        return attribute.hashCode() + (descending ? 7 : 11);
    }

    @Override
    public boolean equals(Object obj)
    {
        if (obj == null)
        {
            return false;
        }

        if (obj == this)
        {
            return true;
        }

        if (!this.getClass().equals(obj.getClass()))
        {
            return false;
        }

        SortCriterion that = (SortCriterion) obj;

        if (this.descending != that.descending)
        {
            return false;
        }

        return LocalUtil.equals(this.attribute, that.attribute);
    }

    @Override
    public String toString()
    {
        return "Sorting[" + attribute + (descending ? "|desc" : "|asc") + "]";
    }

    /**
     * @see #getAttribute
     */
    private final String attribute;

    /**
     * @see #isDescending
     */
    private final boolean descending;
}