public Query newQuery ();
public Query newQuery (Class candidateClass);
public Query newQuery (Extent candidates);
public Query newQuery (Class candidateClass, Collection candidates);
public Query newQuery (Class candidateClass, String filter);
public Query newQuery (Class candidateClass, Collection candidates, String filter);
public Query newQuery (Extent candidates, String filter);
public Query newQuery (String language, Object serialized);
public Query newQuery (Object serialized);

Query objects are used to find persistent objects matching certain criteria. You can obtain a Query instances through one of the PersistenceManager's several newQuery methods. See the chapter covering the Query interface and the PersistenceManager Javadoc for details.