static inner classes/nested classes

[Doug Sherm]

Pleas help to clear up some of my confusion on the topic of static inner classes:

1) If the class is not a static class and just a static member why is the syntax "static class Nest {}" used?

2) And if it is just a member does it follow the rule for other static members that only one copy exists for the class?

3) One last thing: it appears as though the class is being instantiated in the example given in the book. Is that possible for a "static" class?

I'm preparing to take the certification exam for Java 6, and I'm trying to clear up my fuzziness on this subject. The information is on pgs. 680-681 of Sun Certified Programmer for Java 6 Study Guide.

I appreciate any help that anyone can provide.

Thanks in advance,

Doug Sherm

[Ankit Garg]

Doug Sherm wrote:1) If the class is not a static class and just a static member why is the syntax "static class Nest {}" used?

I don't understand this question. Every static member of a class are declared with the static syntax, a static inner class is also a static member of the enclosing class, so why wouldn't you use the static keyword.

Doug Sherm wrote:2) And if it is just a member does it follow the rule for other static members that only one copy exists for the class?

Classes don't have copies, whether there is a static or non-static inner class, there will be one definition of the class loaded by the class loader

Doug Sherm wrote:3) One last thing: it appears as though the class is being instantiated in the example given in the book. Is that possible for a "static" class?

Which example?? Its easier if you show us the example that you are confused with, not everyone has the book which you are referring to or even if they have the book, they might not have it with them everytime...

[Harpreet Singh janda]

Ankit can you please explain the second point a bit more?

[Ankit Garg]

Harpreet to the JVM inner classes are same as top level classes. So each instance of a class doesn't have an associated instance of any non-static inner classes. So whether an inner class is static or non-static, the JVM will only load the class once. After that we can create multiple instances of the inner class. The only difference between static and non-static inner classes is that non-static inner classes have an associated instance of the enclosing class, that's why they can access non-static members of the enclosing class while static inner classes cannot directly access non-static members of the enclosing class (they need to instantiate the enclosing class and access the non-static members on that instance)...

[Abimaran Kugathasan]

Doug Sherm wrote :

1) If the class is not a static class and just a static member why is the syntax "static class Nest {}" used?

You mean, In K&B's book, It is said that,

The class itself isn't really "static"; there's no such thing as a static class............

[Harpreet Singh janda]

Thanks for the explanation Ankit

[Abimaran Kugathasan]

Doug Sherm,

Have a look on Javaworld link