Question

Please, can you explain why the creators of guava prefer to define the constructors as private, and to define static methods create() to create objects ?

Answer 1

Effective Java item 1: Consider static factory methods instead of constructors.

Some of the advantages of static factory methods include:

• They automatically infer type parameters pre-Java 7.
• They allow us to control inheritance patterns: we can subclass collection types within Guava without letting outside code subclass them.
• They let us return an arbitrary subclass of the desired type, letting us hide implementation details better.