Java Map Join joinMapUnmodifiable(Map first, Map second)

Description

Join the two given maps to one by checking if one of the two maps already fulfills everything.

License

Open Source License

Parameter

Parameter	Description
K	The key type
V	The value type
first	The first Map to join
second	The second Map to join

Return

A with the joined content (can be one of the given map if the other is empty or null)

Declaration

public static <K, V> Map<K, V> joinMapUnmodifiable(Map<K, V> first, Map<K, V> second) 

Method Source Code

//package com.java2s;
/*/*from   w  w w . j  a  va 2  s .c  o  m*/
 * Copyright (c) 2009 Stephan Schloepke and innoQ Deutschland GmbH
 *
 * Stephan Schloepke: http://www.schloepke.de/
 * innoQ Deutschland GmbH: http://www.innoq.com/
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

import java.util.Collections;

import java.util.LinkedHashMap;

import java.util.Map;

public class Main {
    /**
     * Join the two given maps to one by checking if one of the two maps already fulfills everything. Be aware that the
     * newly created collection is unmodifiable but will change if the underlying collections change!
     *
     * @param <K>    The key type
     * @param <V>    The value type
     * @param first  The first {@link Map} to join
     * @param second The second {@link Map} to join
     *
     * @return A {@link Map} with the joined content (can be one of the given map if the other is empty or null)
     */
    public static <K, V> Map<K, V> joinMapUnmodifiable(Map<K, V> first, Map<K, V> second) {
        if (first == null || first.isEmpty()) {
            if (second == null || second.isEmpty()) {
                return Collections.emptyMap();
            } else {
                return Collections.unmodifiableMap(second);
            }
        } else if (second == null || second.isEmpty()) {
            return Collections.unmodifiableMap(first);
        } else {
            Map<K, V> temp = new LinkedHashMap<K, V>(first.size() + second.size());
            temp.putAll(first);
            temp.putAll(second);
            return Collections.unmodifiableMap(temp);
        }
    }
}

Related

1. joinAll(Map> map, String separator)
2. joinArgs(Map map, String sep, String split)
3. joinLookup(Iterable elements, String separator, Map lookup)
4. joinMap(Map map)
5. joinMapToString(Map map, String sSeparator, String sMidSeparator)
6. joinMapValue(Map map, char connector)
7. joinOnDelimiter(Map toJoin, char delimiter)
8. joinOnSemicolon(Map toJoin)
9. joinParameters(Map params)