TCPClient.java

import java.net.*;
import java.io.*;
import java.util.*;

public class Client
{
    private ObjectInputStream ois;
    private ObjectOutputStream oos;
    private Socket s;
    private GUIForClient gfc;
    private String server;
    private String username;
    private int port;


    public Client(String server, int port, String username)
    {
        this(server, port, username, null);
    }

    public Client(String server, int port, String username, GUIForClient gfc)
    {
        this.server = server;
        this.port = port;
        this.username = username;
        this.gfc = gfc;
    }

    public boolean start()
    {
        try{
            s = new Socket(server, port);
        }
        catch(Exception e) {
            displayMessage("Error connecting to server: " + e);
            return false;
        }

        String msg = "Connection accepted on IP address " + s.getInetAddress() + " On port: " + s.getPort();
        displayMessage(msg);

        try
        {
            ois = new ObjectInputStream(s.getInputStream());
            oos = new ObjectOutputStream(s.getOutputStream());
        }
        catch(IOException ioe)
        {
            displayMessage("Exception creating new input/output streams: " + ioe);
            return false;
        }

        new serverListenerThread().start();

        try
        {
            oos.writeObject(username);
        }
        catch(IOException ioe) {
            displayMessage("Exception logging in: " + ioe);
            exit();
            return false;
        }

        return true;
    }

    private void displayMessage(String msg){
        if(gfc == null){
            System.out.println(msg);
        }
        else
        {
            gfc.appendStuff(msg + "\n");
        }
    }

    public void sendMessage(messageType msg) {
        try
        {
            oos.writeObject(msg);
        }
        catch(IOException ioe)
        {
            displayMessage("Exception writing to the server: " + ioe);
        }
    }

    private void exit() {
        try
        {
            if(ois != null)
            {
                ois.close();
            }
        }
        catch(Exception e){
        }

        try
        {
            if(oos != null)
            {
                oos.close();
            }
        }
        catch(Exception e)
        {
        }

        try
        {
            if(s != null)
            {
                s.close();
            }
        }
        catch(Exception e)
        {
        }

        if(gfc != null)
        {
            gfc.ifConnectionFails();
        }

    }

    public static void main(String[] args) {
        int portNum = 7257;
        String address = "localhost";
        String name = "Unknown";

        switch(args.length)
        {
            case 0:
            break;

            case 1:
            name = args[0];

            case 2:
            try
            {
                portNum = Integer.parseInt(args[1]);
            }
            catch(Exception e)
            {
                System.out.println("Invalid port number.");
                System.out.println("Usage of this program is as follows: -> java Client (name) (portNum) (address)");
                return;
            }

            case 3:
            address = args[2];

            default:
            System.out.println("Usage of this program is as follows: -> java Client (name) (portNum) (address)");
            return;
        }

        Client client = new Client(address, portNum, name);

        if(!client.start())
        {
            return;
        }

        Scanner scan = new Scanner(System.in);

        while(true)
        {
            System.out.print("Type your message here: -> ");
            String msg = scan.nextLine();

            if(msg.equalsIgnoreCase("EXIT"))
            {
                client.sendMessage(new messageType(messageType.EXIT, ""));
                break;
            }
            else
            {
                client.sendMessage(new messageType(messageType.MESSAGE, msg));
            }
        }
        client.exit();
    }

    public class serverListenerThread extends Thread
    {
        public void run()
        {
            while(true)
            {
                try
                {
                    String msg = (String) ois.readObject();
                    if(gfc == null)
                    {
                        System.out.println(msg);
                        System.out.print("Type your next message: ");
                    }
                    else
                    {
                        gfc.appendStuff(msg);
                    }
                }
                catch(IOException ioe)
                {
                    displayMessage("Server has closed the connection: " + ioe);
                    if (gfc != null)
                    {
                        gfc.ifConnectionFails();
                    }
                    break;
                }
                catch(ClassNotFoundException cnfe)
                {
                }
            }
        }
    }
}