java - How to use "Static factory methods" instead of constructors?

Question

Effective java says "Consider providing static factory methods instead of constructors"

If you have a

 class A {

     public static A getInstance() {
        return new A();
     }
 }

Does it make sense to provide this method for class A , rather than call new A() in the code.

Answer 1

See here for a nice exposition of the main reasons you might want to do this. In summary:

1. Named "constructors".
2. Can return null, if appropriate.
3. Can return an instance of a derived class, if appropriate.
4. Reduce verbosity when instantiating variables of generic types.

Another reason comes to mind that the article doesn't mention: Can implement interesting logic to avoid creating new objects all the time (caching based on parameters, recycling, etc.).