Topic awaiting preservation: Strange Classes.

So I'm working on a Java project for the first time in like forever. A language I've never had been very good at and I'm running into something thats throwing me off.

I have an api I'm using (Smack for XMPP/Jabber traffic). When I compile it I get a bunch of classes named PacketReader$1.class and PacketReader$2.class etc. through $4. What's happening here?



.:[ Never resist a perfect moment ]:.

The normal compiled expression of nested classes : PacketReader$1 is "child class 1 of class packetreader". And so on and so forth.
It's ugly, but it's legit.