Inner class

[David Ulicny]

Hello,
what is the exact difference between inner class and nested class? I read the JLS and I'm not sure if I understand it well.
Is it that inner class must not be static and nested class must be static ?
Thanks for answers.

[Sheldon Fernandes]

Below is the terminology used for classes

Top Level
If a class is not nested, then it is a top level class.

Nested
Every class declared within the body of another class or interface is known as a nested class.

Member
If a nested class has a name and is not declared inside of a method, constructor or any block, then it is a member class.

Inner
If a member class is not static, then it is an inner class.

Local
If a nested class has a name and is declared inside of a method, constructor or any block, then it is a local class.

Anonymous
A nested class which does not have a name is an anonymous class. If a nested class does not have a name, then it can not be called a local class even if it is declared inside of a block. Therefore, an anonymous class is never called a local class.

Sheldon Fernandes

[David Ulicny]

class Outer{
   class Inner{
   }
 
   static class Nested{
   }
}

The class Inner is nested and inner and the class Nested is only nested but not inner?
Am I right?

[Joyce Lee]

David, the Sun tutorial on nested class might help you to clear out the doubt.

  
class EnclosingClass{
    . . .
    // both AStaticNestedClass and InnerClass are nested classes  
    static class AStaticNestedClass { // this is a static nested class
        . . .
    }
    class InnerClass { // this is an inner class
        . . .
    }
}
 

The class Inner is nested and inner and the class Nested is only nested but not inner?
In your example, both the Inner and Nested classes are nested classes.

Joyce

[Peter den Haan]

Beware though that some use the terms "nested class" and "inner class" interchangeably - including Sun itself in some of its early publications So always remain on your toes...

- Peter