i am trying to send an Object via socket.

its object Net

public class Net {
    public List<NetObject> objects; //= new ArrayList<NetObject>(); // place + transition
    public List<ArcObject> arcs; // = new ArrayList<ArcObject>(); // arcs - objects
}

here is the ArcObject class

public class ArcObject implements Observer  {

    public NetObject o1;
    public NetObject o2;
    public String parameter;
}

and here is NetObject class

public class NetObject implements Observer{
public int index; // index of object
public int type; // type - place=1, transition=2 ...
public int x; // position
public int y;
public List<Integer> tokens ; //list of tokens
//public List<ArcObject> arcs = new ArrayList<ArcObject>();
public String guard;
// etc... 
}

then i connect to the server

        String computername=InetAddress.getLocalHost().getHostName();
        kkSocket = new Socket(computername, 4444);
        OutputStream outputStream = null ;
        ObjectOutputStream  out = null ; 
        outputStream = kkSocket.getOutputStream();  
        out = new ObjectOutputStream(outputStream);  

and then i try to send object via socket

out.writeObject(petriNet); //petriNet object is from class Net

but the client gives me an exception

java.io.NotSerializableException: petri.ArcObject

but ArcObject class cant implements Serializable, since it already implements Observer, so how am i supposed to send object via socket which has two lists included. any ideas ?

• java
• sockets
• serializable

You're allowed to implement multiple interfaces. Just comma-separate them in the declaration.

ArcObject and all its members (and their members and so on) need to implement the Serializable interface (it's just a marker interface, no methods to implement).

Oh, and, you can implement multiple interfaces. What you can't do is extend multiple classes.

ArcObject class cant implements Serializable, since it already implements Observer

Yes, it can. A class can implement several interfaces.

You can actually implement more than one interface in Java. Therefore it is possible to implement Observer AND Serializable.