How much code should one put in a constructor?

Question

I was thinking how much code one should put in constructors in Java? I mean, very often you make helper methods, which you invoke in a constructor, but sometimes there are s

Answer 1

Constructor is like an Application Setup Wizard where you do only configuration. If the Instance is ready to take any (possible) Action on itself then Constructor doing well.

Answer 2

As Knuth said, "Premature optimization is the root of all evil."

How much should you put in the consructor? Everything you need to. This is the "eager" approach. When--and only when--performance becomes an issue do you consider optimizing it (to the "lazy" or "over-eager" approaches).

Answer 3

Take a look at this SO question. Even though the other one is for C++, the concepts are still very similar.