Sort a map by value.

SortMap.java

import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

/**
 * Shamelessly stolen from 
 * http://stackoverflow.com/questions/109383/how-to-sort-a-mapkey-value-on-the-values-in-java/2581754#2581754
 */
public class SortMap
{
	/**
	 * Sort a map by value descending.
	 * @param map
	 * @return
	 */
	public static <K, V extends Comparable<? super V>> Map<K, V> sortByValueDescending(Map<K, V> map)
	{
		return sortByValue(map, true);
	}
	
	/**
	 * Sort a map by value ascending.
	 * @param map
	 * @return
	 */
	public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map)
	{
		return sortByValue(map, false);
	}
	
	/**
	 * Sort a map by value.
	 * @param map
	 * @param descending Set to true to sort descending.
	 * @return
	 */
	private static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map, boolean descending)
	{
		List<Map.Entry<K, V>> list = new LinkedList<Map.Entry<K, V>>(map.entrySet());
		Collections.sort(list, new Comparator<Map.Entry<K, V>>()
		{
			@Override
			public int compare(Map.Entry<K, V> o1, Map.Entry<K, V> o2)
			{
				return (o1.getValue()).compareTo(o2.getValue());
			}
		});
		
		// Descending if requested.
		if (descending)
			Collections.reverse(list);
		
		Map<K, V> result = new LinkedHashMap<K, V>();
		for (Map.Entry<K, V> entry : list)
			result.put(entry.getKey(), entry.getValue());
		return result;
	}
}