Java sockets: multiple client threads on same port on same machine?

Question

I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is:

Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the server to read and write data with isolation between clients"

public class Client extends Thread
{
    ...
    void run()
    {
        Socket socket = new Socket("localhost", 1234);
        doIO(socket);  
    }
}

public class Server extends Thread
{
    ...
    void run()
    {
        // serverSocket on "localhost", 1234
        Socket clientSock = serverSocket.accept();
        executor.execute(new ClientWorker(clientSock));
    }
}

Now can I have multiple Client instances on different threads trying to connect on the same port of the current machine?

For example,

   Server s = new Server("localhost", 1234);
   s.start();
   Client[] c = new Client[10];
   for (int i = 0; i < c.length; ++i)
   {
        c.start();
   }

Answer 1

Yes, however only one client will be able to connect per thread execution as written.

You can just put your server run() inside a while true loop to let multiple clients connect. Depending on the executor, they will execute either in series or parallel.

   public class Server extends Thread  
   {  
       ...  
       void run()  
       {  
           while(true){
              // serverSocket on "localhost", 1234  
              Socket clientSock = serverSocket.accept();  
              executor.execute(new ClientWorker(clientSock));  
           }
       }  
   } 

Answer 2

As long as you only have one object trying to bind the port for listening, then there's no problem with multiple clients connecting.