Are methods in static nested classes implicitly static?

Question

Just looking for a confirmation.

public class Indeed{
   public static class Inner implements Runnable{
         public void run()
    {
       System.out.println("Indeed");
    }

  }
    public static void main (String []args)
  {
     Indeed.Inner inner = new Indeed.Inner();
     inner.run();
  }
}

As you can see in the code above, I can declare public void run() without declaring it static. I guess it's implicitly done. Isn't it?

One more question related: Why I cannot use the method run as following: Indeed.Inner.run(); it is static after all, there should not be any need of instantiating the inner member at all? ( I know I am wrong as it does not compile if I do that, however I would like to know why).

Thanks in advance.

The static modifier does not do what you expect on "class", I guess. — Fildor, May 28 '13 at 09:46
[related question](http://stackoverflow.com/questions/70324/java-inner-class-and-static-nested-class) — Supericy, May 28 '13 at 09:50

score 4 · Answer 1 · answered May 28 '13 at 09:46

As you can see in the code above, I can declare public void run() without declaring it static. I guess it's implicitly done. Isn't it?

No.

One more question related: Why I cannot use the method run as following: Indeed.Inner.run();

Becuase it's not static.

static class is only valid for inner classes and you can point to a static class by its enclosing class as Indeed.Inner.

This is different from non-static inner class where you need an instance of the enclosing class to create an instance of the same class. For example:

Indeed.Inner inner = new Indeed().new Inner();

score 2 · Answer 2 · answered May 28 '13 at 09:45

No, run() is an instance method of the static class Inner. A static (inner) class just makes it possible to use an instance of the class without an enclosing parent instance. When you do Indeed.Inner inner = new Indeed.Inner();, you are creating an instance of the static class, and you are invoking it's run() method on this instance.

score 1 · Answer 3 · edited Jun 20 '20 at 09:12

1

http://docs.oracle.com/javase/tutorial/java/javaOO/nested.html

Non-static nested classes (inner classes) have access to other members of the enclosing class

A static nested class interacts with the instance members of its outer class (and other classes) just like any other top-level class.

edited Jun 20 '20 at 09:12

Community

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answered May 28 '13 at 09:48

Suresh Atta

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score 1 · Accepted Answer · answered May 28 '13 at 09:49

A static class is just a regular class, in fact more so than a non-static class.

The difference between a static nested class and a top-level class is just access scoping: the static class can access private members of its enclosing class.

Once you get that cleared up, you won't need to ask the question that you are asking here.

score 0 · Answer 5 · answered May 28 '13 at 09:47

0

Static inner class

public static class Inner implements Runnable

means you can create the instance of them, without having to create the instance of outer class (Indeed)

Indeed.Inner inner = new Indeed.Inner();

Why I cannot use the method run as following: Indeed.Inner.run() ?

the run method is by default not static. To call Indeed.Inner.run() directly, you need to make run() method static too

answered May 28 '13 at 09:47

sanbhat

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'static inner class' is a contradiction in terms. ["An inner class is a nested class that is not explicitly or implicitly declared static."](http://docs.oracle.com/javase/specs/jls/se7/html/jls-8.html#jls-8.1.3). – user207421 May 29 '13 at 00:25

Are methods in static nested classes implicitly static?

5 Answers5