sorter.java

webwork source

/*
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.util;

import java.util.Comparator;

/**
 *	Sorters. Utility sorters for use with the "sort" tag.
 *
 *	@see webwork.view.taglib.iterator.SortIteratorTag
 *	@see SortIteratorFilter
 *	@author Rickard 謆erg ([e-mail])
 *	@version $Revision: 1.9 $
 */
public class Sorter
{
   public Comparator getAscending()
   {
      return new Comparator()
      {
         public int compare(Object o1, Object o2)
         {
            if (o1 instanceof Comparable)
            {
               return ((Comparable)o1).compareTo(o2);
            } else
            {
               String s1 = o1.toString();
               String s2 = o2.toString();
               return s1.compareTo(s2);
            }
         }
      };
   }

   public Comparator getDescending()
   {
      return new Comparator()
      {
         public int compare(Object o1, Object o2)
         {
            if (o2 instanceof Comparable)
            {
               return ((Comparable)o2).compareTo(o1);
            } else
            {
               String s1 = o1.toString();
               String s2 = o2.toString();
               return s2.compareTo(s1);
            }
         }
      };
   }

   public Comparator getComparator(String anExpression, boolean ascending)
   {
      if (ascending)
         return getAscending(anExpression);
      else
         return getDescending(anExpression);
   }

   public Comparator getAscending(final String anExpression)
   {
      return new Comparator()
      {
         private ValueStack stack = new ValueStack();

         public int compare(Object o1, Object o2)
         {
            // Get value for first object
            stack.pushValue(o1);
            Object v1 = stack.findValue(anExpression);
            stack.popValue();

            // Get value for second object
            stack.pushValue(o2);
            Object v2 = stack.findValue(anExpression);
            stack.popValue();

            // Ensure non-null
            if (v1 == null)
               v1 = "";
            if (v2 == null)
               v2 = "";

            // Compare them
            if (v1 instanceof Comparable && v1.getClass().equals(v2.getClass()))
            {
               return ((Comparable)v1).compareTo(v2);
            } else
            {
               String s1 = v1.toString();
               String s2 = v2.toString();
               return s1.compareTo(s2);
            }
         }
      };
   }

   public Comparator getDescending(final String anExpression)
   {
      return new Comparator()
      {
         private ValueStack stack = new ValueStack();

         public int compare(Object o1, Object o2)
         {
            // Get value for first object
            stack.pushValue(o1);
            Object v1 = stack.findValue(anExpression);
            stack.popValue();

            // Get value for second object
            stack.pushValue(o2);
            Object v2 = stack.findValue(anExpression);
            stack.popValue();

            // Ensure non-null
            if (v1 == null)
               v1 = "";
            if (v2 == null)
               v2 = "";

            // Compare them
            if (v2 instanceof Comparable && v1.getClass().equals(v2.getClass()))
            {
               return ((Comparable)v2).compareTo(v1);
            } else
            {
               String s1 = v1.toString();
               String s2 = v2.toString();
               return s2.compareTo(s1);
            }
         }
      };
   }
}