org.apache.myfaces.shared_tomahawk.util.HashMapUtils Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of tomahawk21 Show documentation

JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF2.1 features. A JSF2.1 implementation is required to use this version of the Tomahawk library.

The newest version!

/*
 * 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 org.apache.myfaces.shared_tomahawk.util;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.Iterator;


/**
 * @author Anton Koinov (latest modification by $Author: lu4242 $)
 * @version $Revision: 1202947 $ $Date: 2011-11-16 19:16:48 -0500 (Wed, 16 Nov 2011) $
 */
public class HashMapUtils
{
    //~ Constructors -------------------------------------------------------------------------------

    protected HashMapUtils()
    {
        // block public access
    }

    //~ Methods ------------------------------------------------------------------------------------

    /**
     * Calculates initial capacity needed to hold size elements in
     * a HashMap or Hashtable without forcing an expensive increase in internal
     * capacity. Capacity is based on the default load factor of .75.
     * 
     * Usage: Map map = new HashMap(HashMapUtils.calcCapacity(10));
     * 

     * @param size the number of items that will be put into a HashMap
     * @return initial capacity needed
     */
    public static final int calcCapacity(int size)
    {
        return ((size * 4) + 3) / 3;
    }

    /**
     * Creates a new HashMap that has all of the elements
     * of map1 and map2 (on key collision, the latter
     * override the former).
     *
     * @param map1 the fist hashmap to merge
     * @param map2 the second hashmap to merge
     * @return new hashmap
     */
    public static HashMap merge(Map map1, Map map2)
    {
        HashMap retval = new HashMap(calcCapacity(map1.size() + map2.size()));

        retval.putAll(map1);
        retval.putAll(map2);

        return retval;
    }

     /**
     * spit out each name/value pair
     */
    public static String mapToString(Map map)
    {
        Set entries = map.entrySet();
        Iterator iter = entries.iterator();
        StringBuffer buff = new StringBuffer();
        while (iter.hasNext())
        {
            Map.Entry entry = (Map.Entry) iter.next();
            buff.append("[" + entry.getKey() + "," + entry.getValue() + "]\n");
        }
        return buff.toString();
    }

}