Private constructor in abstract class

Question

In Java what is the purpose of using private constructor in an abstract class?

In a review I got this question, and I am curious, for what situation we need to use

Answer 1

1. As mentioned, to be used as a common, internal-use only constructor.

2. Abstract or not abstract, it's not uncommon to declare a private default constructor on a class containing only static public methods [helper methods] to prevent instantiating the class.