bugs in client\server program - can't connect to remote server

[Sid]

hello!

I have a client/server program in which client lets user input two
numbers and the server adds the numbers and returns the sum to client.

the problems I am having are:

1. client is not able to connect to remote server. it is only
connecting to local host.

2. if a string seperated by "non-numeric" characters (e.g. 34a2dd) is
sent, both client and server throw an uncaught exception. i need to
fix the client or server or both and give useful feedback to the user.
i need to do the error checking of user i/p so that user enters only
integers seperated by whitespace.

I am attaching my code.
I am new to java and probably don't know much.
'shall greatly appreciate your help.

thanks in advance,
siddharth

code:

// usage: java TCPAdditionServer3 <port number>
// default port is 7777
// connection to be closed by client
// this server handles only one connection

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

class TCPAdditionServer3{
public static void main(String[] args)throws Exception{
String clientSentence,capitalizedSentence;
int sum=0;
String sumString = "";
InetAddress serverAddress;
int portNumber = 7777;
Socket connectionSocket = null;

try {
portNumber = Integer.parseInt(args[0]);
}
catch (Exception e) {
System.out.println(" port = 7777 (default)");
portNumber = 7777;
}

// create welcoming socket at port number specified by user or
7777 if no choice is specified by user
ServerSocket welcomeSocket=new ServerSocket(portNumber);

//server infinite loop
while(true){
try {
// wait, on welcoming socket for contact by
client
connectionSocket=welcomeSocket.accept();
} catch (IOException e) {
System.out.println("Accept failed:");
System.exit(-1);
}

// create input stream, attached to socket
BufferedReader inFromClient=new BufferedReader(new
InputStreamReader(connectionSocket.getInputStream()));
// create output stream, attached to socket
DataOutputStream outToClient=new
DataOutputStream(connectionSocket.getOutputStream());

// read in line from socket
clientSentence=inFromClient.readLine();

StringTokenizer st= new StringTokenizer(clientSentence);
while(st.hasMoreTokens()) {
sum += Integer.parseInt(st.nextToken());
}

System.out.println("Waiting for connections on port " +
connectionSocket.getLocalPort() + " ... ");
System.out.println("Received connection from " +
connectionSocket.getInetAddress() + ":" +
connectionSocket.getLocalPort());

sumString = Integer.toString(sum);
clientSentence = " ";
capitalizedSentence = clientSentence + sumString + "\n";

//write out line to socket
outToClient.writeBytes(capitalizedSentence);

//connection closed by client
try {
connectionSocket.close();
System.out.println("Connection closed by client");
}
catch (IOException e) {
System.out.println(e);
}

}
}

}

code:

// usage: java TCPAdditionClient3 <server> <port>
// default port is 7777

/**
* TCPAdditionClient1.java
*
* @author Siddharth Jain
* @version 3.0
*/

/** Client Code */

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

/** this is the main class */
class TCPAdditionClient3{
public static void main(String[] args)throws Exception{

String sentence,sentc,portNumberString;
int portNumber= 7777;
String hostName = "localhost";
String modifiedSentence;
InetAddress clientAddress;
/** create input stream */
BufferedReader inFromUser1=new BufferedReader(new
InputStreamReader(System.in));

/** read arguments */
if(args.length == 2) {
hostName = args[0];
try {
portNumber = Integer.parseInt(args[1]);
System.out.println("client user i/p port number " +
portNumber);
}
catch (Exception e) {
System.out.println(" server port = 7777 (default)");
portNumber = 7777;
}
}

/** connect to server */
try{
/** create client socket, connect to server */
Socket clientSocket=new Socket(hostName,portNumber);

if (clientSocket.isConnected()== true);
{
System.out.println("Connecting to Server " +
clientSocket.getInetAddress() + ":" + clientSocket.getPort() + "..." +
"Connected");
}

/** create output stream attached to socket */
DataOutputStream outToServer=new
DataOutputStream(clientSocket.getOutputStream());
/** create input stream attached to socket */
BufferedReader inFromServer=new BufferedReader(new
InputStreamReader(clientSocket.getInputStream()));

System.out.println();
System.out.println("Enter a string of integers seperated by
non-numeric characters:");

sentence = inFromUser1.readLine();
/**send line to server */
outToServer.writeBytes(sentence+"\n");
/** read line from server */
modifiedSentence=inFromServer.readLine();
System.out.println("From Server-----> The Sum
is:"+modifiedSentence);

try {
clientSocket.close();
}
catch(IOException e) {
System.out.println(e);
}

} catch(UnknownHostException e) {
System.err.println(" Don't know about host: ");
System.exit(1);
} catch(IOException e) {
System.err.println(" Couldn't get I/O for the connection");
System.exit(1);
}

}
}