Sending Email in Java but having error Could not connect to SMTP host: localhost, port: 25;

Question

I am sending email through java but it giving me an error.I did'nt know where is the error so kindly help me where is the error identify the error.

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
public class MailSending
{
public static void main(String [] args)
{    
  // Recipient's email ID needs to be mentioned.
  String to = "abc@gmail.com";

  // Sender's email ID needs to be mentioned
  String from = "xyz@live.com";

  // Assuming you are sending email from localhost
  String host = "localhost";

  // Get system properties
  Properties properties = System.getProperties();

  // Setup mail server
  properties.setProperty("mail.smtp.host", host);

  // Get the default Session object.
  Session session = Session.getDefaultInstance(properties);

  try{
     // Create a default MimeMessage object.
     MimeMessage message = new MimeMessage(session);

     // Set From: header field of the header.
     message.setFrom(new InternetAddress(from));

     // Set To: header field of the header.
     message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

     // Set Subject: header field
     message.setSubject("This is the Subject Line!");

     // Now set the actual message
     message.setText("This is actual message");

     // Send message
     Transport.send(message);
     System.out.println("Sent message successfully....");
  }catch (MessagingException mex) {
     mex.printStackTrace();
  }
}
}

Console Output:

javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
nested exception is:
java.net.ConnectException: Connection refused: connect
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1227)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:322)
at javax.mail.Service.connect(Service.java:236)
at javax.mail.Service.connect(Service.java:137)
at javax.mail.Service.connect(Service.java:86)
at javax.mail.Transport.send0(Transport.java:150)
at javax.mail.Transport.send(Transport.java:80)
at MailSending.main(MailSending.java:45)

I shall be thankful to identify the problem for me :)