Java - No enclosing instance of type Foo is accessible

Question

I have the following code:

class Hello {
    class Thing {
        public int size;

        Thing() {
            size = 0;
        }
    }

    public stat         


        

Answer 1

static class Thing will make your program work.

As it is, you've got Thing as an inner class, which (by definition) is associated with a particular instance of Hello (even if it never uses or refers to it), which means it's an error to say new Thing(); without having a particular Hello instance in scope.

If you declare it as a static class instead, then it's a "nested" class, which doesn't need a particular Hello instance.