Sets the value of the entry in the map for the given key - Java java.util

Java examples for java.util:Map Entry

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Description

Sets the value of the entry in the map for the given key

Demo Code

/**/*w w w.  j a v a 2 s .  com*/
 * 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.
 */
//package com.java2s;

import java.util.ArrayList;

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

public class Main {
    /**
     * Sets the value of the entry in the map for the given key, though if the
     * map already contains a value for the given key then the value is appended
     * to a list of values.
     *
     * @param map the map to add the entry to
     * @param key the key in the map
     * @param value the value to put in the map
     */
    @SuppressWarnings("unchecked")
    public static void appendValue(Map<String, Object> map, String key,
            Object value) {
        Object oldValue = map.get(key);
        if (oldValue != null) {
            List<Object> list;
            if (oldValue instanceof List) {
                list = (List<Object>) oldValue;
            } else {
                list = new ArrayList<Object>();
                list.add(oldValue);
                // replace old entry with list
                map.remove(key);
                map.put(key, list);
            }
            list.add(value);
        } else {
            map.put(key, value);
        }
    }
}

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