The best thing you can do is:
1.) Make a new package within your source called "Commands"
2.) Create a CommandManager.java (I think there is a tutorial around somewhere, I dunno)
3.) Put all commands in their own files and execute the commands using the manager.
4.) Execute the CommandManager in the client.java.
Example:
client.java - case 103: (commands packet)
If you can't find a tutorial, PM me and I'll set you up with a CommandManager my source has.Code:Command().handlePacket(this, packetType, packetSize);