HashMapUtils.java

/* 
 * Copyright (C) 2015 Adrien Guille <adrien.guille@univ-lyon2.fr>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package main.java.fr.ericlab.sondy.core.utils;

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

/**
 *
 *   @author Adrien GUILLE, Laboratoire ERIC, Université Lumière Lyon 2
 */
public class HashMapUtils {
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByAscValue( Map<K, V> map ){
        List<Map.Entry<K, V>> list =
            new LinkedList<>( 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() );
            }
        } );

        Map<K, V> result = new LinkedHashMap<>();
        for (Map.Entry<K, V> entry : list)
        {
            result.put( entry.getKey(), entry.getValue() );
        }
        return result;
    }
    
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByDescValue( Map<K, V> map ){
        List<Map.Entry<K, V>> list =
            new LinkedList<>( 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() );
            }
        } );

        Map<K, V> result = new LinkedHashMap<>();
        for (Map.Entry<K, V> entry : list)
        {
            result.put( entry.getKey(), entry.getValue() );
        }
        return result;
    }
}