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/*
* KeyMap.java May 2007
*
* Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
*
* 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.
*/
package org.simpleframework.common;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Set;
/**
* The <code>KeyMap</code> object is used to represent a map of values
* keyed using a known string. This also ensures that the keys and
* the values added to this hash map can be acquired in an independent
* list of values, ensuring that modifications to the map do not have
* an impact on the lists provided, and vice versa. The key map can
* also be used in a fore each look using the string keys.
*
* @author Niall Gallagher
*/
public class KeyMap<T> extends LinkedHashMap<String, T> implements Iterable<String> {
/**
* Constructor for the <code>KeyMap</code> object. This creates
* a hash map that can expose the keys and values of the map as
* an independent <code>List</code> containing the values. This
* can also be used within a for loop for convenience.
*/
public KeyMap() {
super();
}
/**
* This is used to produce an <code>Iterator</code> of values
* that can be used to acquire the contents of the key map within
* a for each loop. The key map can be modified while it is been
* iterated as the iterator is an independent list of values.
*
* @return this returns an iterator of the keys in the map
*/
public Iterator<String> iterator() {
return getKeys().iterator();
}
/**
* This is used to produce a <code>List</code> of the keys in
* the map. The list produced is a copy of the internal keys and
* so can be modified and used without affecting this map object.
*
* @return this returns an independent list of the key values
*/
public List<String> getKeys() {
Set<String> keys = keySet();
if(keys == null) {
return new ArrayList<String>();
}
return new ArrayList<String>(keys);
}
/**
* This is used to produce a <code>List</code> of the values in
* the map. The list produced is a copy of the internal values and
* so can be modified and used without affecting this map object.
*
* @return this returns an independent list of the values
*/
public List<T> getValues() {
Collection<T> values = values();
if(values == null) {
return new ArrayList<T>();
}
return new ArrayList<T>(values);
}
}
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