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<body>
<p>
Commons-Collections contains implementations, enhancements and utilities
that complement the Java Collections Framework.
</p>
<p>
The Apache Jakarta Commons Collections Framework component adds a significant
amount of enhancements to the standard JDK collections. These enhancements
come in the form of new interfaces, new implementations and utility classes.
</p>
<p>
See also the <code>java.util</code> package for the standard Java collections.
</p>
<h4>Main features</h4>
<p>
Commons-Collections defines a number of key interfaces:
</p>
<table border="1" cellspacing="0" cellpadding="3">
<tr bgcolor="#CCCCFF" class="TableHeadingColor">
<th>Interface</th><th>Description</th>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.Bag}
</td>
<td valign="top">
A new <code>Collection</code> subinterface that stores each object together
with the number of occurances. Methods are provided to get the number of
occurances, and to add and remove a certain number of that object.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.Buffer}
</td>
<td valign="top">
A new <code>Collection</code> subinterface that allows objects to be removed
in some well-defined order. Methods enable the next item to be peeked and removed.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.BidiMap}
</td>
<td valign="top">
A new <code>Map</code> subinterface that allows lookup from key to value and
from value to key with equal ease.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.OrderedMap}
</td>
<td valign="top">
A new <code>Map</code> subinterface that is used when a map has an order, but is
not sorted. Methods enable bidriectional iteration through the map.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.MapIterator}
</td>
<td valign="top">
A new <code>Iterator</code> subinterface specially designed for maps. This iterator
avoids the need for entrySet iteration of a map, and is simpler to use.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.ResettableIterator}
</td>
<td valign="top">
A new <code>Iterator</code> subinterface that allows the iteration to be reset back
to the start. Many iterators in this library have this functionality.
</td>
</tr>
<tr>
<td>
{@link org.apache.commons.collections.Closure}<br />
{@link org.apache.commons.collections.Predicate}<br />
{@link org.apache.commons.collections.Transformer}<br />
{@link org.apache.commons.collections.Factory}<br />
</td>
<td valign="top">
A group of <i>functor</i> interfaces that provide plugin behaviour to various
collections and utilities.
</td>
</tr>
</table>
<p>
In addition to the interfaces, there are many implementations.
Consult each subpackage for full details of these.
</p>
</body>