Getting Null pointer Exception while using the Java mail api to send mail from local host using gmail smtp.

Question

In servlet class i am initializing all the variable in init method

private String host="smtp.gmail.com";
private String port="465";
private String user="[email protected]";
private String pass="pass";
public void init()
{
    // reads SMTP server setting from web.xml file
    ServletContext context = getServletContext();
    host = context.getInitParameter("host");
    port = context.getInitParameter("port");
    user = context.getInitParameter("user");
    pass = context.getInitParameter("pass");
}

In EmailUtility class i am having the code below

    Properties properties = new Properties();
    properties.put("mail.smtp.host", host);
    properties.put("mail.smtp.port", port);
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");


    Authenticator auth = new Authenticator() 
    {
        public PasswordAuthentication getPasswordAuthentication()
        {
            return new PasswordAuthentication(userName, password);
        }
    };

    Session session = Session.getInstance(properties, auth);


    Message msg = new MimeMessage(session);

    msg.setFrom(new InternetAddress(userName));
    InternetAddress[] toAddresses = { new InternetAddress(toAddress) };
    msg.setRecipients(Message.RecipientType.TO, toAddresses);
    msg.setSubject(subject);
    msg.setSentDate(new Date());
    msg.setText(message);   
    Transport.send(msg);

Stack Trace of Exception is

    at java.lang.Thread.run(Unknown Source)
    java.lang.NullPointerException
    at java.util.Hashtable.put(Unknown Source)
    at EmailUtility.sendEmail(EmailUtility.java:31)
    at EmailSendingServlet.doPost(EmailSendingServlet.java:52)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

I am trying to test this mail sending mechanism on my local host using gmail smtp. Unable to track why this Exception occurs. I have also tried to run this by changing the port number but ended up with the same problem.

Where specifically in this code block is this exception being thrown? — Makoto
– Makoto, Commented Apr 19, 2015 at 6:29
In EmailUtility class at properties.put("mail.smtp.host", host); — Ankit Sahu
– Ankit Sahu, Commented Apr 19, 2015 at 6:34

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

host is coming back null. Since Properties extends Hashtable, you're making use of Hashtable's put method. But, put will throw an NPE if either the key or value are null:

Throws:

NullPointerException - if the key or value is null

Ensure that you're getting a value back from all invocations of context.getInitParameter and that they're making their way to their correct variables.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Apr 19, 2015 at 6:45

Makoto

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