When to use a Constructor and when to use getInstance() method (static factory methods)?

Question

1. When and how should we use a constructor

   Foo bar = new Foo();
   

2. And when and how should we use getInstance() (static factory

Answer 1

One case in which I always prefer a static factory over a regular constructor is when I know the object construction will be slowish. I do simple initialization on constructor, but if I need to create something heavy I'll use a static method and document the behavior.