title: javax.mail.Authenticator null pointer Exception
body: <p>I am developing a program that can send an email without user interaction. For this, I use javax.mail.Authenticator. However, when I run the program it gives me null pointer exception. Here is my code:</p>
  
  <pre><code>public class Mail extends javax.mail.Authenticator {
  private String _user;
  private String _pass;
  
  private String[] _to;
  private String _from;
  
  private String _port;
  private String _sport;
  
  private String _host;
  
  private String _subject;
  private String _body;
  
  private boolean _auth;
  
  private boolean _debuggable;
  
  private Multipart _multipart;
  
  
  public Mail() {
      _host = "smtp.gmail.com"; // default smtp server
      _port = "465"; // default smtp port
      _sport = "465"; // default socketfactory port
  
      _user = ""; // username
      _pass = ""; // password
      _from = ""; // email sent from
      _subject = ""; // email subject
      _body = ""; // email body
  
      _debuggable = false; // debug mode on or off - default off
      _auth = true; // smtp authentication - default on
  
      _multipart = new MimeMultipart();
  
      // There is something wrong with MailCap, javamail can not find a handler for the multipart/mixed part, so this bit needs to be added.
      MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
      mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
      mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
      mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
      mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
      mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
      CommandMap.setDefaultCommandMap(mc);
  }
  
  public Mail(String user, String pass) {
      this();
  
      _user = user;
      _pass = pass;
  }
  
  public boolean send() throws Exception {
      Properties props = _setProperties();
  
      if(!_user.equals("") &amp;&amp; !_pass.equals("") &amp;&amp; _to.length &gt; 0 &amp;&amp; !_from.equals("") &amp;&amp; !_subject.equals("") &amp;&amp; !_body.equals("")) {
          Session session = Session.getInstance(props, this);
  
          MimeMessage msg = new MimeMessage(session);
  
          msg.setFrom(new InternetAddress(_from));
  
          InternetAddress[] addressTo = new InternetAddress[_to.length];
          for (int i = 0; i &lt; _to.length; i++) {
              addressTo[i] = new InternetAddress(_to[i]);
          }
          msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
  
          msg.setSubject(_subject);
          msg.setSentDate(new Date());
  
          // setup message body
          BodyPart messageBodyPart = new MimeBodyPart();
          messageBodyPart.setText(_body);
          _multipart.addBodyPart(messageBodyPart);
  
          // Put parts in message
          msg.setContent(_multipart);
  
          // send email
          Transport.send(msg);
  
          return true;
      } else {
          return false;
      }
  }
  
  public void addAttachment(String filename) throws Exception {
      BodyPart messageBodyPart = new MimeBodyPart();
      DataSource source = new FileDataSource(filename);
      messageBodyPart.setDataHandler(new DataHandler(source));
      messageBodyPart.setFileName(filename);
  
      _multipart.addBodyPart(messageBodyPart);
  }
  
  @Override
  public PasswordAuthentication getPasswordAuthentication() {
      return new PasswordAuthentication(_user, _pass);
  }
  
  private Properties _setProperties() {
      Properties props = new Properties();
  
      props.put("mail.smtp.host", _host);
  
      if(_debuggable) {
          props.put("mail.debug", "true");
      }
  
      if(_auth) {
          props.put("mail.smtp.auth", "true");
      }
  
      props.put("mail.smtp.port", _port);
      props.put("mail.smtp.socketFactory.port", _sport);
      props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
      props.put("mail.smtp.socketFactory.fallback", "false");
  
      return props;
  }
  
  // the getters and setters
  public String getBody() {
      return _body;
  }
  
  public void setBody(String _body) {
      this._body = _body;
  }
  
  public void setTo(String[] toArr) {
      this._to = toArr;
  }
  
  public void setFrom(String string) {
      this._from = string;
  }
  
  public void setSubject(String string) {
      this._subject = string;
  }
  
  // more of the getters and setters …..
  </code></pre>
  
  <p>}`</p>
  
  <p>Here is my main Activity:</p>
  
  <pre><code>public class AutomaticEmailActivity extends Activity {
  private Mail m;
  /** Called when the activity is first created. */
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.main); 
      m = new Mail("yourEmail@domain.tld", "yourpassword"); 
  }
  
  public void sendEmail(View view){
      String[] toArr = {"toemail1@domain1.tld"}; // This is an array, you can add more emails, just separate them with a coma
      m.setTo(toArr); // load array to setTo function
      m.setFrom("fromEmail@domain.tld"); // who is sending the email 
      m.setSubject("subject"); 
      m.setBody("your message goes here"); 
  
      try { 
          m.addAttachment("/sdcard/myPicture.jpg");  // path to file you want to attach
          if(m.send()) { 
              // success
              Toast.makeText(AutomaticEmailActivity.this, "Email was sent successfully.", Toast.LENGTH_LONG).show(); 
          } else { 
              // failure
              Toast.makeText(AutomaticEmailActivity.this, "Email was not sent.", Toast.LENGTH_LONG).show(); 
          } 
      } catch(Exception e) { 
          // some other problem
          Toast.makeText(AutomaticEmailActivity.this, "There was a problem sending the email.", Toast.LENGTH_LONG).show(); 
      } 
  
  }
  </code></pre>
  
  <p>}
  and here my blog </p>
  
  <blockquote>
    <p>FATAL EXCEPTION: main
                                                                                  java.lang.NullPointerException
                                                                                      at com.example.unknown.location.MainActivity.onSensorChanged(MainActivity.java:235)
                                                                                      at android.hardware.SystemSensorManager$ListenerDelegate$1.handleMessage(SystemSensorManager.java:256)
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                                      at android.os.Looper.loop(Looper.java:176)
                                                                                      at android.app.ActivityThread.main(ActivityThread.java:5317)
                                                                                      at java.lang.reflect.Method.invokeNative(Native Method)
                                                                                      at java.lang.reflect.Method.invoke(Method.java:511)
                                                                                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
                                                                                      at dalvik.system.NativeStart.main(Native Method)</p>
  </blockquote>
  
  <p>What happens when I run my code is that it shows: <code>There was a problem sending the email.</code> </p>
  
  <p>The third Toast in my code and if I replaced this message with e.getMessage().toString it returns NullPointerException</p>