Question

Trying to serialize and send Lot object to socket. Getting error:

java.io.NotSerializableException: com.server.ClientServiceThread

Why?

public class ClientServiceThread extends Thread  {... // form here called sendObj ...}

public class FlattenLot {
public void sendObj(){
        try {
            out = new ObjectOutputStream(oStream);
            out.writeObject(lot); // error
            out.flush();
            out.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

Lot class:

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import java.util.Date;
import java.util.Calendar;

public class Lot implements Serializable{
private static final long serialVersionUID = 1L;
    public ArrayList<ClientServiceThread> clientBidsLog = new ArrayList<ClientServiceThread>();
    public ArrayList<Integer> bidLog = new ArrayList<Integer>();

    private List<Integer> bids = new ArrayList<Integer>();
    private List<ClientServiceThread> clients = new ArrayList<ClientServiceThread>();

    private  String NAME;
    private  int INITIAL_PRICE;

    private int MAX_BID = 0;
    public volatile boolean notAvailable = false;
Lot(String name, int initPrice){
        NAME = name;
        INITIAL_PRICE = initPrice;
    }
public synchronized String getName(){return NAME;}
public synchronized int getInitPrice(){return INITIAL_PRICE;}
public synchronized void subscribe(ClientServiceThread t){
        clients.add(t);
      }
public synchronized void unsubscribe(ClientServiceThread t){
        clients.remove(t);
      }
public  synchronized boolean makeBid(ClientServiceThread t,int i){
          if(i > INITIAL_PRICE && i > MAX_BID){
                clientBidsLog.add(t);
                bidLog.add(i);
                bids.add(i);
                MAX_BID = i;
                t.LAST_BID = i;
                notifyAllSubscribers("New bid: "+this.getMaxBid()+" made by "+this.clientBidsLog.get(this.clientBidsLog.size()-1).CLIENT_NAME);
                return true;
          }else{
                return false;
          }


          }
public synchronized void notifyAllSubscribers(String msg){
        for (ClientServiceThread client : clients){
              client.lotUpdated(this, msg);
            }
    }
public synchronized int getMaxBid(){return MAX_BID;}

    private Date time;

    public Lot() {
        time = Calendar.getInstance().getTime();
    }

    public Date getTime() {
        return time;
    }
    }

Answer 1

Lot contains

public ArrayList<ClientServiceThread> clientBidsLog 
private List<ClientServiceThread> clients

If you wish this field to be serialized mark the ClientServiceThread serializable too

if you don’t want it to be serialized just mark it transient like

public transient ArrayList<ClientServiceThread> clientBidsLog 
private transient List<ClientServiceThread> clients