How can I keep a java app that updates a database running?

I'm currently working on a simple webapp that shows the health of a device for a project. Its fairly simple I'm just displaying data from a database. Currently hosting it on firebase.

I've been asked to make a java program that stores data in a database at specific timepoints, this database will then be used for the webapp display. I can do this but I'm a little lost when it comes to hosting the web app.

How can I keep the java program running and updating the database when someone navigates to the webapp.

If anyone could suggest a direction to proceed it would be really appreciated. I apologize if this doesn't follow SO guidelines on questions. I'm new to the computer science world.