I want to implement notifications that pop up on a phone the same way a text would. So, it buzzes when a notification is sent even when your phone is not in use and even when my app isn't running, exactly how the default calendar app works on android devices. Literally exactly as the calendar app, where if a certain date and time is approaching, a notification will be sent. I've found answers involving servers and internet access, but I don't need nor do I want that because my app is all local to a person's device. How do I code a notification like this? Please give a code example like, if the date is January 1, a notification saying "Happy New Year" will be sent.