Mastering Java: The Ultimate Quiz for 'Thinking in Java'

What is a consequence of a class with all private constructors?

1. It cannot be instantiated

2. It enables singleton pattern

3. It allows subclassing

4. It is automatically final

The correct answer is: It cannot be instantiated

A consequence of a class with all private constructors is that it cannot be instantiated. This means that an object cannot be created from this class, making it essentially useless for any practical purpose. Option B is incorrect because the singleton pattern does not necessarily require all private constructors. Only one constructor needs to be private to enforce the singleton pattern. Option C is incorrect because a class with all private constructors cannot be subclassed since the subclass would not be able to access the private constructor. Option D is incorrect because a class with all private constructors is not automatically final, which means it can still be extended by other classes.