title: Android notification is not showing
body: <p>I need a program that will add a notification on Android. And when someone clicks on the notification, it should lead them to my second activity.</p>
  
  <p>I have established code. The notification should be working, but for some reason it is not working. The <code>Notification</code> isn't showing at all. I don't know what am I missing.</p>
  
  <p>Code of those files:</p>
  
  <pre><code>Notification n = new Notification.Builder(this)
          .setContentTitle("New mail from " + "test@gmail.com")
          .setContentText("Subject")
          .setContentIntent(pIntent).setAutoCancel(true)
          .setStyle(new Notification.BigTextStyle().bigText(longText))
          .build();
  
  NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
  // Hide the notification after it's selected
  
  notificationManager.notify(0, n);
  </code></pre>