Question

I am new to java and have been scratching my head understanding some its concepts.
I am following the tutorial Java tutorial. However, I cannot find the usefulness of using Static Nested Classes. I mean I think I need some good examples as to why I should want to use it. Can someone provided me some codes as examples so I can understand it better?
thax

Answer 1

The benefit of a static nested class over an “ordinary” class is that you can use it to reflect the relationship between two classes.

For example in the JDK there is java.util.Map and java.util.Map.Entry.

java.util.Map.Entry is declared as a public static interface and doing it this way clearly signposts its relationship to Map. It could have been defined as java.util.MapEntry but doing it as a static nested interface makes it clear that it has a strong relationship to Map.

So you’d probably only use static nested class when the nested class would only ever be used in the context of its parent.