2004-01-30 20:33:00 -05:00
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<?xml version="1.0" encoding="ISO-8859-1"?>
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2004-02-17 20:00:08 -05:00
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<!--
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Copyright 2004-2006 The Apache Software Foundation
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2004-02-17 20:00:08 -05:00
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<document>
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<properties>
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2006-03-25 08:56:26 -05:00
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<title>History</title>
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<author email="commons-dev@jakarta.apache.org">Commons Documentation Team</author>
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</properties>
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<body>
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<section name="History of Commons Collections">
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<p>
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Commons-Collections is a classic example of an open-source project evolving over time.
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This page documents some of the key stages.
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</p>
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<p>
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<b>Collections 1.0</b> was a gathering of different Collection, Comparator, Iterator and
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Utility classes written elsewhere in Jakarta.
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At this stage, the component focussed mainly on getting re-use of code by making
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2006-05-07 16:02:04 -04:00
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everything available together.
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</p>
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<p>
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All classes were placed in one package except the comparators, which had their own subpackage.
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</p>
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<p>
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<b>Collections 2.0</b> started the process of growth. The Bag interface was added with
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various implementations. Also added were additional collections implementations.
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</p>
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<p>
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All classes were placed in one package except the comparators, which had their own subpackage.
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</p>
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<p>
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<b>Collections 2.1</b> increased the growth again. The Buffer interface was added, unifying
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various previous implementations. Numerous decorators were added as inner classes that
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behave like the unmodifiable or synchronized JDK decorators.
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</p>
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<p>
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As the size of the component increased, the iterators were broken out into their own subpackage.
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Thus there were now three packages, main, comparator and iterator.
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</p>
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<p>
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2006-05-14 16:20:39 -04:00
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<b>Collections 3.0</b> represented a re-birth of collections after an 18 month absence.
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Many, many classes were added to CVS but not released including primitive and
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event-generating classes. In order to control the size of the collections distribution,
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these became two new projects - primitives and events.
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</p>
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<p>
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New interfaces BidiMap, MapIterator, ResettableIterator and KeyValue were added.
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Also added were many new implementations of existing collections, especially Maps.
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</p>
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<p>
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As more decorators were added the decision was taken to create a new subpackage for
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the decorators (no more inner classes). However, it became clear that whether a class was
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a decorator or not was not the most important division in finding a collection.
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As a result of this, and the general ongoing growth in the component, a full subpackage
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layout was chosen - one subpackage for each principal collections interface.
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</p>
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<p>
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2006-05-14 16:20:39 -04:00
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Essentially the 3.0 release represented the result of changing from a 'dumping ground'
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of re-used collections to a component <b>designed</b> for the purpose.
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2004-05-29 10:23:25 -04:00
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Of course, backwards compatibility has been retained during all transitions using deprecation.
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</p>
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<p>
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2006-05-14 16:20:39 -04:00
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<b>Collections 2.1.1</b> was a patch release to v2.1.
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2004-06-22 18:24:29 -04:00
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Unfortunately, v3.0 created a <a href="compatibility.html">binary incompatibility</a> in the IteratorUtils class.
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2004-05-29 10:23:25 -04:00
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This patch was created as a work around, enabling v2.1.1 to be compatible with v3.1.
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</p>
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<p>
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<b>Collections 3.1</b> fixed some bugs in v3.0 and adds a few new enhancements.
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2004-06-22 18:24:29 -04:00
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The most notable change is a new list implementation, TreeList, that is well balanced for insertions and removals at any index.
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2006-05-14 16:20:39 -04:00
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Other changes included more classes implementing Serializable and a ReferenceIdentityMap.
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</p>
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<p>
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<b>Collections 3.2</b> combined bug fixes and some new features.
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Notably MultiValueMap is a new more flexible implementation of MultiHashMap.
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2004-01-30 20:33:00 -05:00
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</p>
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</section>
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</body>
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</document>
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