Java HashMap Create createHashMap(int expectedMapSize)

Description

Utility method that creates an java.util.HashMap with its initialCapacity calculated to minimize rehash operations

License

Open Source License

Declaration

public static <K, V> Map<K, V> createHashMap(int expectedMapSize) 

Method Source Code

//package com.java2s;
/*/*from   ww  w  .ja  va  2s  . c o m*/
 * Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
 *
 * Licensed 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.HashMap;
import java.util.Map;

public class Main {
    private static final double HASHMAP_DEFAULT_LOAD_FACTOR = 0.75;

    /**
     * Utility method that creates an {@link java.util.HashMap} with its initialCapacity calculated
     * to minimize rehash operations
     */
    public static <K, V> Map<K, V> createHashMap(int expectedMapSize) {
        int initialCapacity = (int) (expectedMapSize / HASHMAP_DEFAULT_LOAD_FACTOR) + 1;
        return new HashMap<K, V>(initialCapacity);
    }
}

Related

1. createHashMap()
2. createHashMap()
3. createHashMap(int initialCapacity)
4. createHashMap(int initialCapacity)
5. createHashMap(int size)
6. createHashMap(Object key, Object value)