How to properly divide an application into modules?

Question

Java

Are there any rules for splitting an application into modules?
Maybe it is described in books on application design?
Or it comes from the needs of the project: for example, if there are some components that rarely change, we put them in a separate module.
UPD: By splitting into modules, I mean one parent maven module. It contains other modules and all of them are linked in the pom of the parent module.

Answer 1

mmm, are you talking about "modules" as a set of packages? If so, then it makes sense to put into a separate module what is planned to be reused later. Let's say some internal solutions, on the basis of which your application is already being built, etc.
In large projects, the application is divided into modules so that a separate team can work on each module. Something like this.
Well, if modules mean units or classes, then you need to read about SOLID and GRASP.

Answer 2

Well, if we talk about theory, there is always a data access level, a business logic level, and an interface part. And it would be nice - if all these parts do not know how the other one works inside. Those. The interface should not know that the data is taken from the database by SQL queries.

Answer 3

It can be divided simply by logic, the interface is separate, etc., it will be much more convenient to work