face in java.util" class="externalLink"><code>Set</code></a> and <a href="../QueryEngine.html" title="interface in com.googlecode.cqengine.engine"><code>QueryEngine</code></a>, thus providing
 <a href="../../ConcurrentIndexedCollection.html#retrieve(com.googlecode.cqengine.query.Query)"><code>ConcurrentIndexedCollection.retrieve(com.googlecode.cqengine.query.Query)</code></a> methods for performing queries on the collection to retrieve
 matching objects, and <a href="../../ConcurrentIndexedCollection.html#a