001: /*
002: * Copyright 2003-2004 The Apache Software Foundation
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016: package org.apache.commons.collections.map;
017:
018: import java.util.Comparator;
019: import java.util.SortedMap;
020:
021: import org.apache.commons.collections.Factory;
022: import org.apache.commons.collections.Transformer;
023:
024: /**
025: * Decorates another <code>SortedMap</code> to create objects in the map on demand.
026: * <p>
027: * When the {@link #get(Object)} method is called with a key that does not
028: * exist in the map, the factory is used to create the object. The created
029: * object will be added to the map using the requested key.
030: * <p>
031: * For instance:
032: * <pre>
033: * Factory factory = new Factory() {
034: * public Object create() {
035: * return new Date();
036: * }
037: * }
038: * SortedMap lazy = Lazy.sortedMap(new HashMap(), factory);
039: * Object obj = lazy.get("NOW");
040: * </pre>
041: *
042: * After the above code is executed, <code>obj</code> will contain
043: * a new <code>Date</code> instance. Furthermore, that <code>Date</code>
044: * instance is mapped to the "NOW" key in the map.
045: * <p>
046: * <strong>Note that LazySortedMap is not synchronized and is not thread-safe.</strong>
047: * If you wish to use this map from multiple threads concurrently, you must use
048: * appropriate synchronization. The simplest approach is to wrap this map
049: * using {@link java.util.Collections#synchronizedSortedMap}. This class may throw
050: * exceptions when accessed by concurrent threads without synchronization.
051: * <p>
052: * This class is Serializable from Commons Collections 3.1.
053: *
054: * @since Commons Collections 3.0
055: * @version $Revision: 348007 $ $Date: 2005-11-21 22:52:57 +0000 (Mon, 21 Nov 2005) $
056: *
057: * @author Stephen Colebourne
058: * @author Paul Jack
059: */
060: public class LazySortedMap extends LazyMap implements SortedMap {
061:
062: /** Serialization version */
063: private static final long serialVersionUID = 2715322183617658933L;
064:
065: /**
066: * Factory method to create a lazily instantiated sorted map.
067: *
068: * @param map the map to decorate, must not be null
069: * @param factory the factory to use, must not be null
070: * @throws IllegalArgumentException if map or factory is null
071: */
072: public static SortedMap decorate(SortedMap map, Factory factory) {
073: return new LazySortedMap(map, factory);
074: }
075:
076: /**
077: * Factory method to create a lazily instantiated sorted map.
078: *
079: * @param map the map to decorate, must not be null
080: * @param factory the factory to use, must not be null
081: * @throws IllegalArgumentException if map or factory is null
082: */
083: public static SortedMap decorate(SortedMap map, Transformer factory) {
084: return new LazySortedMap(map, factory);
085: }
086:
087: //-----------------------------------------------------------------------
088: /**
089: * Constructor that wraps (not copies).
090: *
091: * @param map the map to decorate, must not be null
092: * @param factory the factory to use, must not be null
093: * @throws IllegalArgumentException if map or factory is null
094: */
095: protected LazySortedMap(SortedMap map, Factory factory) {
096: super (map, factory);
097: }
098:
099: /**
100: * Constructor that wraps (not copies).
101: *
102: * @param map the map to decorate, must not be null
103: * @param factory the factory to use, must not be null
104: * @throws IllegalArgumentException if map or factory is null
105: */
106: protected LazySortedMap(SortedMap map, Transformer factory) {
107: super (map, factory);
108: }
109:
110: //-----------------------------------------------------------------------
111: /**
112: * Gets the map being decorated.
113: *
114: * @return the decorated map
115: */
116: protected SortedMap getSortedMap() {
117: return (SortedMap) map;
118: }
119:
120: //-----------------------------------------------------------------------
121: public Object firstKey() {
122: return getSortedMap().firstKey();
123: }
124:
125: public Object lastKey() {
126: return getSortedMap().lastKey();
127: }
128:
129: public Comparator comparator() {
130: return getSortedMap().comparator();
131: }
132:
133: public SortedMap subMap(Object fromKey, Object toKey) {
134: SortedMap map = getSortedMap().subMap(fromKey, toKey);
135: return new LazySortedMap(map, factory);
136: }
137:
138: public SortedMap headMap(Object toKey) {
139: SortedMap map = getSortedMap().headMap(toKey);
140: return new LazySortedMap(map, factory);
141: }
142:
143: public SortedMap tailMap(Object fromKey) {
144: SortedMap map = getSortedMap().tailMap(fromKey);
145: return new LazySortedMap(map, factory);
146: }
147:
148: }
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