Java - Socket getLocalPort() Method

Description

The Java Socket getLocalAddress() returns the local port number to which this socket is bound. If the socket was bound prior to being closed, then this method will continue to return the local port number after the socket is closed.

Declaration

Following is the declaration for java.net.Socket.getLocalPort() method.

public int getLocalPort()

Parameters

NA

Return Value

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

Exception

NA

Example 1

The following example shows the usage of Java Socket getLocalPort() methd to get the port to which the socket is bound. As first step, we've created a Socket instance using no argument constructor. Then in order to create a SocketAddress object, we've initialized an InetAddress instance of localhost address. Using InetSocketAddress object, we've created a SocketAddress object and then using bind() method, we bind the address to the socket. Once done, we're printing the local port using getLocalPort() method and local address using getLocalAddress() method as shown. In the end, we closed the socket using close() method.

package com.tutorialspoint;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  
      InetAddress inetAddress=InetAddress.getByName("localhost");  
      SocketAddress socketAddress=new InetSocketAddress(inetAddress, 6066);  
      socket.bind(socketAddress); 
      
      System.out.println("Port number: "+socket.getLocalPort()); 
      System.out.println("Local Address: "+socket.getLocalAddress()); 
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Port number: 6066
Local Address: /127.0.0.1

Example 2

The following example shows the usage of Java Socket getLocalPort() methd to get the port to which the socket is bound. As first step, we've created a Socket instance using no argument constructor. Now using bind() method, we bind a null address to the socket. Once done, we're printing, local port being assigned to the socket using getLocalPort() method and local address using getLocalAddress() method as shown. In the end, we closed the socket using close() method.

package com.tutorialspoint;

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

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  
      socket.bind(null); 

      System.out.println("Port number: "+socket.getLocalPort()); 
      System.out.println("Local Address: "+socket.getLocalAddress()); 
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Port number: 50277
Local Address: 0.0.0.0/0.0.0.0

Example 3

The following example shows the usage of Java Socket getLocalPort() methd to get the port where the socket is already closed. As first step, we've created a Socket instance using no argument constructor. Then in order to create a SocketAddress object, we've initialized an InetAddress instance of localhost address. Using InetSocketAddress object, we've created a SocketAddress object. Using socket.close(), we're closing the socket. Now we're printing local port being assigned to the socket using getLocalPort() method and local address using getLocalAddress() method as shown. In the end, we closed the socket using close() method.

package com.tutorialspoint;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  
      InetAddress inetAddress=InetAddress.getByName("localhost");  
      SocketAddress socketAddress=new InetSocketAddress(inetAddress, 6066);  
      socket.bind(socketAddress); 
      socket.close();
      
      System.out.println("Port number: "+socket.getLocalPort()); 
      System.out.println("Local Address: "+socket.getLocalAddress()); 
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Port number: 6066
Local Address: 0.0.0.0/0.0.0.0