org.apache.myfaces.shared_impl.util.HashMapUtils Maven / Gradle / Ivy
/*
* 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_impl.util;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.Iterator;
/**
* @author Anton Koinov (latest modification by $Author: matzew $)
* @version $Revision: 557350 $ $Date: 2007-07-18 13:19:50 -0500 (Wed, 18 Jul 2007) $
*/
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();
}
}