Kryonet Registering Classes

Newbie & Debugging Questions
#1

I’m pretty deep into my project at this point, yet I’ve come across an issue with registering a class.


Mon Mar 03 10:22:00 EST 2014 ERROR:java.lang.IllegalArgumentException: Class is not registered: org.newdawn.slick.Animation$Frame
Note: To register this class use: kryo.register(org.newdawn.slick.Animation$Frame.class);

When I attempt to register: Serializer.register(org.newdawn.slick.Animation$Frame.class); I have the following syntax error: cannot be referenced using its binary name.

I realize there is something wrong with the ‘$’ character and Frame, yet I don’t know what to do. I’ve tried registering just register(org.newdawn.slick.Animation.class); yet the issue still remains.

Additional Information:
The new Packet I’ve created contains a SpriteSheet and Animation variable.

Any thoughts on this?!
Thanks.

#2

Hmmm.
From what I think I remember, $ means that the class file has been created from another class file. What I mean is that you probably cannot register classes that are within other classes. You need to specify a class that has it’s own file and is not within other class.

#3

That is interesting and I’ll obviously be investigating this further… If anyone has any insights, please feel open to share 8)

#4

Here is a short example.

Animation.java

public class Animation {
		
		public static class Frame {
			
		}
	}

I’m guessing this is how you got it setup.

Just take Frame and put it into it’s own .java file.

Animation.java

public class Animation {
		
	}

Frame.java

public class Frame {
		
	}
#5

$ indicates an internal class nested in another one. You probably only register Animation, but you need to register both Animation and Animation.Frame.

#6

That is how I have my Packet infrastructure set up, not really the bug though.


public class Packet {

        public static class Packet1 {

            // ...

        }

        public static class Packet2 {

            // ...

        }
}

and I register via


Kryo Serializer = client.getKryo();
Serializer.register(Packet.Packet1.class);
Serializer.register(Packet.Packet2.class);

My issue comes about from code inside one of my packets. I have an object, Player, which has always been able to exist as a local variable of Packet1 (lets say)


public class Packet {

        public static class Packet1 {

            Player p = new Player();
            
            // not shown: get & set function for object p

        }

Recently I have added another object, which exists in Player


public class Player() {

        Spell s = new Spell();

            // not shown: get & set function for object s and initialization steps
}

Inside Spell:


public class Spell implements DrawableObject {

        public Animation animation = null;  //  object from: org.newdawn.slick.Animation
        public SpriteSheet sprite_sheet = null;  // object from: org.newdawn.slick.SpriteSheet

            // not shown: get & set function for objects and initialization steps

}

Here is the full trace:


Exception in thread "Client" com.esotericsoftware.kryo.KryoException: Encountered unregistered class ID: 7709
Serialization trace:
animation (spells.Spell)
MySpells (client_framework.Player)
p1 (client_framework.Team)
Team1 (client_framework.GameLobby)
G (client_framework.Packet$Packet2PlayerInit)
	at com.esotericsoftware.kryo.Kryo.readClass(Kryo.java:623)
	at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:747)
	at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:340)
	at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:293)
	at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:671)
	at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:224)
	at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:760)
	at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:340)
	at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:293)
	at com.esotericsoftware.kryo.Kryo.readObjectOrNull(Kryo.java:732)
	at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:229)
	at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:671)
	at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:224)
	at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:671)
	at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:224)
	at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:671)
	at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:224)
	at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:760)
	at com.esotericsoftware.kryonet.KryoSerialization.read(KryoSerialization.java:57)
	at com.esotericsoftware.kryonet.TcpConnection.readObject(TcpConnection.java:137)
	at com.esotericsoftware.kryonet.Client.update(Client.java:239)
	at com.esotericsoftware.kryonet.Client.run(Client.java:317)
	at java.lang.Thread.run(Unknown Source)

The compiler gets hung up at the variable ‘animation’ located in Spell.java due to it being incorrectly registered (or something along those lines).

I thought what agentd said, yet for whatever reason I don’t know how to find the accurate path in registering Animation.Frame

This is not recognized:


Serializer.register(org.newdawn.slick.Animation.Frame.class);  // illegal, does not exist?

Thank you for your time.

#7

I’m not sure you can serialize Slick internal classes with kryo just like that. like for example every class used by kryo needs an empty constructor too right ? but if you just use the lib as a jar you cannot implement that anyway
also imo you shouldnt save more to file than necessary but thats another discussion…