Question

I have a chat program. Now the code works for communicate between client and server via command line. But it gives an exception (java.net.SocketException: Socket is closed) while running. Please help me to fix that problem.

In a java chat program,how will the communication be implemented between client and server?

ie.

client<–>server (between server and client)

             or

client A<–>server<–>client B (server act as a bridge between two clients)

Is the 2 way communication can be implemented through a single socket?
Are there any other methods ?
How to communicate more than one client simultaneously?

server code

class Server
{
ServerSocket server;
Socket client;
public Server()
{
    try
    {
        server = new ServerSocket(2000);
        System.out.println("\tServer Started..........");
        while (true)
        {
            client = server.accept();
            Send objsend = new Send(client);
            Recive objrecive = new Recive(client);
            //client.close();
        }
    }
    catch (Exception e)
    {
        System.out.println("Exception4 " + e);
    }
}
    public static void main(String arg[])
    {
        new Server();
    }
}
class Recive implements Runnable
{
    Socket client;
    public Recive(Socket client1)
    {
        client=client1;
        Thread trsend=new Thread(this);
        trsend.start();
    }
    public void run()
    {
        ObjectInputStream ois;
        Message M=new Message();
        try
        {
            ois = new ObjectInputStream(client.getInputStream());
            M = (Message)ois.readObject();
            M.display();
            ois.close();
        }
        catch (Exception e)
        {
            System.out.println("Exception1 " + e);
        }
    }
}    
class Send implements Runnable
{
    Socket client;
    public Send(Socket client1)
    {
        client=client1;
        Thread trrecive=new Thread(this);
        trrecive.start();
    }
    public void run()
    {
        Message M=new Message();
        InputStreamReader isr=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(isr);
        try
        {
            System.out.println("Me(server)");
            M.strmessage=br.readLine();
            ObjectOutputStream oos=new ObjectOutputStream(cli    ent.getOutputStream());
            oos.writeObject((Message)M);
            oos.flush();
            oos.close();
        }
        catch (Exception e)
        {
            System.out.println("Exception " + e);
        }
    }
}

client code

class Client
{
public static void main(String arg[])
{
    try
    {

        Send objsend=new Send();
        Recive objrecive=new Recive();
    }
    catch(Exception e)
    {
        System.out.println("Exception "+e);
    }

}
}
class Send implements Runnable
{

public Send()
{
    Thread trsend=new Thread(this);
    trsend.start();
}
public void run()
{

    try
    {
        Message M=new Message();
        InputStreamReader isr=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(isr);
        while(true)
        {
            System.out.println("Me(client)");
            M.strmessage=br.readLine();

            Socket client=new Socket("localhost",2000);
            ObjectOutputStream oos=new ObjectOutputStream(client.getOutputStream());
            oos.writeObject((Message)M);

            oos.flush();
            oos.close();
        }
    }
    catch(Exception e)
    {
        System.out.println("Exception "+e);
    }
}
}
class Recive implements Runnable
{
public Recive()
{
    Thread trrecive=new Thread(this);
    trrecive.start();
}
public void run()
{

    try
    {
        while(true)
        {
        Socket client=new Socket("localhost",2000);
        ObjectInputStream ois=new ObjectInputStream(client.getInputStream());
        Message CNE=(Message)ois.readObject();
        CNE.display();

        ois.close();
        }

    }
    catch(Exception e)
    {
        System.out.println("Exception "+e);
    }
}
}

Answer 1

First of all, don’t close the streams in every run().

Secondly, check whether port for server which you are using is free.