new bie question-- top-level classess

[RT]

I am preapring for my SCJP exam. I have some good experience in c/c++. I started my prepration with RHE and side by side taking mock exams to my confidence level. I come across the words "top-level classes" and sometimes "top-level classes (not inner class)". Can someone explain what exactly a "top-level" class mean with respect to the package, inner classes, etc..
Thanks
Ramesh

[Jane Zheng]

Hi, Ramesh:
Let me try it first. Correct me if I am wrong.
Top-leve classes: they are members of packages.
Nested top-level classes: Inner classes with static modifier.
A local classes: defined in a blocks.
Anonymous classes: combine delcare & creation, have no names.
Jane Z.

[Ajith Kallambella]

'RT'
PROPER NAMES ARE NOW REQUIRED!!
Read this post for more details.
Ajith

[Jane Griscti]

Just to add to Jane's post, here's a code example

class TopLevel {
    static class TopLevelNested {
       // declared within another class but
       // because of 'static' treated as a top level
       // class ie NOT a member of the enclosing class
       // can be instantiated on its own
       // ie new TopLevelNested();
    }
    class InnerClass {
       // declared within another class
       // treated as a member of that class
       // can only be instantiated as an instance
       // thru the outer class
       // ie new TopLevel().new InnerClass()
    }
    {
        class LocalInnerClass {
           // declared within any code block
           // ie a method, initializer
           // not a member of the enclosing class
           // can only be declared within the enclosing
           // code block
           // ie can be declared here as new LocalInnerClass()
        }
    }
    // can't declare new LocalInnerClass() here as outside
    // containing code block
    // create an anonymous class when it is declared    
    // can't have a constructor as it has no name
    TopLevel anon = new TopLevel() {
        // method to override an original
        // method in TopLevel class
    }    
}

Hope that helps.
------------------
Jane

[zulfiqar raza]

Originally posted by Jane Griscti:
[B]Just to add to Jane's post, here's a code example

snip 
    // create an anonymous class when it is declared    
    // can't have a constructor as it has no name
    TopLevel anon = new TopLevel() {
        // method to override an original
        // method in TopLevel class
    }    
}

[/B]

Jane, are you trying to depict an anonymous class? Is this right?
thanks,
Zulfiqar

[Jane Griscti]

Hi Zulfiqar,
Yes. I was trying to show that you can create an Anonymous class using any existing class. For example, if you had a class named <code>Attr</code> that had a method <code>public Object setValue(Object nv)</code> you could create an Anonymous class based on <code>Attr</code> by doing something like:

Attr name = new Attr("Name") {    
    public Object setValue(Object nv) {
      // code for new implementation of setValue
      // goes here
    }
}

You can call any of the original constructors but you can't redefine a constructor as technically the anonymous class doesn't have a name.

------------------
Jane