In Java inner class final static works without constructor only

Question

I have an inner class which looks like this:

class Inner {
    final static String ok = "something";
    final static String nok = new String("something");
}

A compile time error occurs in the second declaration but not in the first one. Seems as if non-static inner classes not allow explicit invocation of constructor. Also static initializer is not allowed.

Can anyone explain the background?

See also this question - https://stackoverflow.com/questions/18156543/constants-and-inner-classes — Alex Shesterov, Oct 01 '20 at 10:08

score 0 · Answer 1 · answered Oct 01 '20 at 10:20

If you make your inner class static it would work:

public class Outer {

   static class Inner {
       final static String ok = "something";
       //Now this is ok also
       final static String nok = new String("something");
       }
}

You must explicitly declare inner class to be static if you want to allow explicit invocation of a constructor.This is because inner class is not explicitly or implicitly declared static and your job is to mark it as such if you want to use constructor invocation inside it.

In Java inner class final static works without constructor only

1 Answers1