Pros and cons of package private classes in Java?

Question

I am learning Java recently, and I came across the notion of package-private classes, which is the default if we don\'t specify anything. But then I realized:

Answer 1

Apart from encapsulation, one of the main advantages of using package-private classes is that they do not appear in the javadoc of your project. So if you use some helper classes which have no other use but to help your public classes do something clients need, it makes sense to make them package private as you want to keep things as simple as possible for users of the library.

As an example, you can have a look at a library that I have developed. The javadoc only contains 5 interfaces and 12 classes although the source code has a lot more. But what is hidden is mostly internal layers that provide no added-value for a client (typically all the abstract base classes are hidden).

There are also many examples in the JDK.