Java Socket bind() method

The bind() method of Java Socket class binds the socket to a local address. If the specified address is null, then the system will automatically pick up a port number and a valid local address to bind with the socket.

Syntax

Parameter

The parameter 'bindpoint' represents the SocketAddress to bind.

Return

Throws

IOException - if the bind operation fails, or if the socket is already bound.

IllegalArgumentException - if the bindpoint is a SocketAddress subclass not supported by this socket.

SecurityException - if the security manager exists and its checkListen method doesn't allow the bind to the local port.

Example 1

import java.io.IOException;
import java.net.*;
public class JavaSocketBindExample1 {
    public static void main(String[] args) throws IOException {
      Socket socket = new Socket();
      InetAddress inetAddress=InetAddress.getByName("localhost");
      //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        System.out.println("Inet address: "+socket.getInetAddress());
        System.out.println("Port number: "+socket.getLocalPort());
    }
}

Test it Now

Output:

Inet address: null
Port number: 1085

Example 2

import java.io.IOException;
import java.net.*;
public class JavaSocketBindExample2 {
    public static void main(String[] args) throws IOException {
      Socket socket = new Socket();
      InetAddress inetAddress=InetAddress.getByName("localhost");
      //the port should be greater or equal to 0, else it will throw an error
        int port=-1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        System.out.println("Inet address: "+socket.getInetAddress());
        System.out.println("Port number: "+socket.getLocalPort());
    }
}

Test it Now

Output:

Exception in thread "main" java.lang.IllegalArgumentException: port out of range:-1085
	at java.net.InetSocketAddress.checkPort(InetSocketAddress.java:143)
	at java.net.InetSocketAddress.(InetSocketAddress.java:188)
	at com.javaTpoint.JavaSocketBindExample2.main(JavaSocketBindExample2.java:12)

Example 3

import java.io.IOException;
import java.net.*;
public class JavaSocketBindExample3 {
    public static void main(String[] args) throws IOException {
      Socket socket = new Socket();
      InetAddress inetAddress=InetAddress.getByName("localhost");
      //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //closing the socket
        socket.close();
        //binding the  socket with the inetAddress and port number
        //It will throw an exception, as the socket is already closed
        socket.bind(socketAddress);
        System.out.println("Inet address: "+socket.getInetAddress());
        System.out.println("Port number: "+socket.getLocalPort());
    }
}

Test it Now

Output:

Exception in thread "main" java.net.SocketException: Socket is closed
	at java.net.Socket.bind(Socket.java:625)
	at com.javaTpoint.JavaSocketBindExample3.main(JavaSocketBindExample3.java:17)

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