Java Map Merge mergeMaps(Map m1, Map m2)

Description

same as clojure's (merge-with merge m1 m2)

License

Apache License

Declaration

private static Map mergeMaps(Map m1, Map m2) 

Method Source Code

//package com.java2s;
/*//ww  w.  j  a  v  a2  s  .  c  o m
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.Map;

public class Main {
    /**
     * same as clojure's (merge-with merge m1 m2)
     */
    private static Map mergeMaps(Map m1, Map m2) {
        if (m2 == null) {
            return m1;
        }
        for (Object o : m2.entrySet()) {
            Map.Entry entry = (Map.Entry) o;
            Object k = entry.getKey();

            Map existing = (Map) m1.get(k);
            if (existing == null) {
                m1.put(k, entry.getValue());
            } else {
                existing.putAll((Map) m2.get(k));
            }
        }
        return m1;
    }
}

Related

1. mergeMap(Map map, Object[]... pairs)
2. mergeMap(Map primaryValues, Map defaultValues)
3. mergeMap(Map first, Map second)
4. mergeMapIntoMap(Map> source, Map> destination)
5. mergeMapList(List> list)
6. mergeMaps(Map mainMap, Map defaultMap, String[] keys, boolean enforceValues)
7. mergeMaps(Map dest, Map inserts)
8. mergeMaps(Map into, Map from, boolean override)
9. mergeMaps(Map m1, Map m2)