Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * 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.Collection;

import java.util.concurrent.ConcurrentMap;

public class Main {
    /**
     * If map already has a value associated with the key it adds values to that
     * value, otherwise it will put values to the map.  Do not reuse values.
     *
     * @param key    Key under which we are adding values
     * @param values Values we want to add
     * @param map    Map which we are adding values to
     * @param <K> Key
     * @param <V> Value
     * @param <C> Collection
     * @return New value associated with the key
     */
    public static <K, V, C extends Collection<V>> C addConcurrent(K key, C values, ConcurrentMap<K, C> map) {
        C currentValues = map.get(key);
        if (currentValues == null) {
            currentValues = map.putIfAbsent(key, values);
            if (currentValues == null) {
                return values;
            }
        }
        synchronized (currentValues) {
            currentValues.addAll(values);
        }
        return currentValues;
    }
}