Question

I have been reading the tutorial Controlling Access to Members of a Class. I am confused what might be good use case for using package-private. Because as I understand, you can always change your package declaration to whatever the package declaration of such a class and act as if that is a public class. I understand that this is not a good thing to do, but what is stopping me?

Answer 1

Because as I understand, you can always change your package declaration to whatever the package declaration of such a class and act as if that is a public class

Well, for one thing, the access modifiers are there to help the developer. There’s always ways around them, such as via reflection for instance.

I understand that this is not a good thing to do, but what is stopping me?

Not much really!

As a developer you can however distribute your classes in sealed .jar-files which basically means that you’re not letting anyone else in to your packages.

From Sealing Packages within a JAR File

Sealing Packages within a JAR File

Packages within JAR files can be optionally sealed, which means that all classes defined in that package must be archived in the same JAR file. You might want to seal a package, for example, to ensure version consistency among the classes in your software.