java - How do I connect to the server socket using the ip address and port number? (client is running on a different machine than server)

Question

Client program

public class client implements Runnable {

protected static String server_IP = "141.117.57.42";
private static final int server_Port = 5555 ;
protected static String client_IP ;


public static void main(String[] args) throws IOException{
    final  String host = "localhost";
    int init = 0  ;
    
    try {
        InetAddress iAddress = InetAddress.getLocalHost();
        client_IP = iAddress.getHostAddress();
        System.out.println("Current IP address : " +client_IP);
    } catch (UnknownHostException e) {
    }
    
    try {System.out.println("hello1");
        Socket socket = new Socket(server_IP,server_Port);
        System.out.println("hello3");
        init = initialize(socket);
       
    }catch (SocketException e) {
        System.out.println("Error: Unable to connect to server port ");
    }

    
    if (init ==  0 ){
        System.out.println("error: Failed to initialize ");
        System.exit(0);
        
    }
    //Thread init_Thread = new Thread();
}
private static int initialize(Socket socket ) throws IOException{
    System.out.println("hello");
    int rt_value = 0 ;
    
    OutputStream os = socket.getOutputStream();
    BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    PrintWriter pw = new PrintWriter(os, true);
    
    System.out.println("server: " + br.readLine());
    pw.println("192.343.34.321");
   // BufferedReader userInputBR = new BufferedReader(new InputStreamReader(System.in));
    //String userInput = userInputBR.readLine();
    
    //out.println(userInput);
    
    socket.close();
    return rt_value = 1 ;
    
    
    
}
public void run(){
    
}
}

server side program

public class server {

protected static String server_IP ;

public static void main(String[] args) throws IOException {
   
    
    int server_Port = 5555 ;



    try {
        InetAddress iAddress = InetAddress.getLocalHost();
        server_IP = iAddress.getHostAddress();
        System.out.println("Server IP address : " +server_IP);
    } catch (UnknownHostException e) {
    }
    
        ServerSocket serverSocket = new ServerSocket(server_Port);
    
    
        while (true) {
            Socket socket = serverSocket.accept();
            
             OutputStream os = socket.getOutputStream();
            PrintWriter pw = new PrintWriter(os, true);
            InputStreamReader isr = new InputStreamReader(socket.getInputStream());
            pw.println("Connection confirmed ");
            BufferedReader br = new BufferedReader(isr);
            String str = br.readLine();
            
            pw.println("your ip address is " + str);
            
            pw.close();
           //socket.close();

            //System.out.println("Just said hello to:" + str);
        }
    

How do I connect to the server socket using the ip address and port number (client is running on a different machine than server).

When I change the server_IP in client to "local host", it works perfectly.

Answer 1

To connect in your code you use:

Socket socket = new Socket(server_IP,server_Port);

So you could use:

Socket socket = new Socket("192.168.1.4", 5555);

It looks like you have this in your code so I'm not sure what problem you're having.

Don't forget that you have to setup your router to forward ports if it is located outside of your local network.

http://www.wikihow.com/Set-Up-Port-Forwarding-on-a-Router

Don't forget that if you are running a firewall, this can also interfere with the connection.