Java Map Reverse reverseMap(Map origMap)

Description

reverse Map

License

Open Source License

Declaration

public static Map<Object, Object> reverseMap(Map<Object, Object> origMap) 

Method Source Code

//package com.java2s;
/*//from   w  w w .j  a  va 2  s.co m
 * Copyright 2012 The Solmix Project
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.gnu.org/licenses/ 
 * or see the FSF site: http://www.fsf.org. 
 */

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;
import java.util.Map;

public class Main {

    public static Map<Object, Object> reverseMap(Map<Object, Object> origMap) {
        if (origMap == null)
            return null;
        Map<Object, Object> reverseMap = new HashMap<Object, Object>();
        for (Object key : origMap.keySet()) {
            putMultiple(reverseMap, origMap.get(key), key);
        }
        return reverseMap;
    }

    public static Map<Object, Object> putMultiple(Map<Object, Object> map, Object key, Object value) {
        Object existingValue = map.get(key);
        if (existingValue == null)
            map.put(key, value);
        else if (existingValue instanceof List)
            ((List) existingValue).add(value);
        else
            map.put(key, buildList(existingValue, value));
        return map;
    }

    /**
     * @param lists
     * @return
     */
    public static List<Object> buildList(List<Object>... lists) {
        List<Object> result = new ArrayList<Object>();
        for (List<Object> list : lists) {
            result.add(list);
        }
        return result;
    }

    /**
     * Build array object into List
     * 
     * @param lists
     * @return
     */
    public static List<Object> buildList(Object... lists) {
        List<Object> result = new ArrayList<Object>();
        for (Object list : lists) {
            result.add(list);
        }
        return result;
    }
}

Related

1. reverseMap(Map map)
2. reverseMap(Map map)
3. reverseMap(Map map)
4. reverseMap(Map map)
5. reverseMap(Map map)
6. reverseMap(Map map)
7. reverseMap(Map keyIdMap, Map keyValueMap)
8. reverseMapLookup(Map map, V value)
9. reverseMapping(Map value2keys, Map map)