Java embedded class, when to use static or non-static?

Question

I am doing an exercise about Java class. The code is as follows.

I can run the code without problem if I add a static modifier before the embedded call Explorer. However, if I do not add the "static", I would see the following error:

Illegal static declaration in inner class Government.Explorer modifier 'static' is only allowed in constant variable declarations.

BTW, the exercise is from CS61B spring 2018 from UC Berkeley. Original code is provided here:

public class Government {
    private int treasury = 5;

    public static Government greaterTreasury(Government a, Government b) {
        if (a.treasury > b.treasury) {
            return a;
        }
        return b;
    }


   public static class Explorer {
        public static void doStuff(Government a, Government b) {
            Government favorite = Government.greaterTreasury(a, b);
            System.out.println("The best government has treasury " + favorite.treasury);            
        }
    }

   public static void main(String[] args){
      Government a = new Government();
      a.treasury = 10;
      Government b = new Government();
      b.treasury = 11;
      Government.Explorer.doStuff(a, b);

   }

}

Snippets are only for Javascript/html/css, please don't use them for Java: use a normal code block instead (as I have done in my edit). — Mark Rotteveel, Dec 06 '18 at 14:49

score 0 · Answer 1 · answered Dec 05 '18 at 21:27

0

You can't reference a non-static inner class without an instance of the outer class.

An inner class can't have static members (other than constants)

See Why can't we have static method in a (non-static) inner class?

answered Dec 05 '18 at 21:27

swpalmer

3,890
2
23
31

Java embedded class, when to use static or non-static?

1 Answers1