There is no way to rewind cursor in Java.

At the same time other languages supports this:
http://api.mongodb.org/ruby/1.5.2/Mongo/Cursor.html#rewind%21-instance_method
http://api.mongodb.org/python/2.1.1/api/pymongo/cursor.html#pymongo.cursor.Cursor.rewind
http://www.php.net/manual/en/mongocursor.rewind.php