Java ServerSocket getLocalPort() Method

The getLocalPort() method of ServerSocket class is used to give the port number of the server on which this socket is listening. If the socket was bound before being closed, then this method will continue to return the port number after the socket is closed.

Syntax

Parameter:

No Parameter.

Returns:

The port number to which this socket is listening or -1 if the socket is not bound yet.

Example 1

ServerApplication:

import java.io.IOException;
import java.net.*;
import java.nio.channels.ServerSocketChannel;
public class MainServer extends Thread {
	private ServerSocket s;
	  public MainServer () throws IOException {
	    s = new ServerSocket(1408);
	    s.setSoTimeout(10000);    
	  }
	  public void run() {
	    while (true) {
	      try {
System.out.println("Waiting for client to connect with server on port " + s.getLocalPort() + "...");
	        Socket client = s.accept();
	        System.out.println("Now server Connected to  " + client.getRemoteSocketAddress());
	        client.close();
	      } catch (Exception s) {
	        System.out.println("Socket timed out!");
	        break;
	      } 
	    }
	  }
	  public static void main(String[] args) {
		    try {
		      Thread t = new MainServer ();
		      t.start();
		    } catch (IOException e) {
		      e.printStackTrace();
		    }
		  }
}

ClientApplication

import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;

public class ClientApplication {

	public static void main(String arg[]) throws UnknownHostException,IOException
	{
	Socket s=new Socket("127.0.0.1",1408);
	System.out.println("Connected on LocalPort " + s.getLocalPort() + "...");
	}
}

Example 2

ServerApplication

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

public class SocketDetail {
	public static void main(String args[])
	{
		int port=1408;
		try
		{
		ServerSocket s = new ServerSocket(port);
			System.out.println("Server initialized on port " + port);
			//calling getLocalPort
			s.getLocalPort();
			{
			while(true)
			s.accept();
			}
		}
		catch (Exception e)
		{
		System.out.println("Socket error");
		}
	}
	}

clientApplication:

import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;

public class ClientApplication {

	public static void main(String arg[]) throws UnknownHostException,IOException
	{
	Socket s=new Socket("127.0.0.1",1408);
	System.out.println("Connected on LocalPort " + s.getLocalPort() + "...");
	}
}

Output: