Which classes need to be supplied by any JVM?

[David Holmes - Sun Microsystems]

As Martin stated what you are looking for is not part of the JVMS nor 
the JLS, but the platform specification, which is essentially the entire 
set of Java API's as found for example here:

http://java.sun.com/javase/6/docs/index.html

But the implementation of those classes will then have dependencies on 
other implementation specific classes, so I'm not sure that you will be 
able to establish a transitive closure of required classes that is 
independent of the JVM in question.

If you were thinking about this from a basic language perspective - eg 
we must have Object, and we must have Class, and array implies 
Serializable etc, then there is a core set of classes that form the 
transitive closure of the JVM bootstrap process. If you are interested 
in that then -XX:+TraceClassLoading (might need a debug VM) will give 
you the set used by a particular VM. But again this list is dependent on 
how those classes are implemented themselves, so the list is JVM dependent.

HTH

David Holmes

Martin Buchholz said the following on 08/21/09 03:32:
> The set of all public APIs that must be part of the java se platform
> are tested by the platform tck, in particular by the "signature test",
> and you can get the sources for that test (for research only)
> and from that it should be possible (with work) to get a list of
> all required classes.  But that's a very large list, so is probably not
> what you want.  In practice, the subset of rt.jar of public classes
> matching java.* or javax.* is a pretty good approximation.
> 
> Martin
> 
> On Thu, Aug 20, 2009 at 08:26, Carsten Otto 
> <otto at informatik.rwth-aachen.de <mailto:otto at informatik.rwth-aachen.de>> 
> wrote:
> 
>     Hello,
> 
>     I am working on automated termination analysis of Java Bytecode and I am
>     missing an important bit of information in the Java Virtual Machine
>     Specification (JVMS). I'd be happy to get some help from you!
> 
>     Every JVM needs to provide certain classes including code for their
>     native
>     methods, e.g. java.lang.Object (obvious) and java.io.Serializable
>     (because
>     every array implements it). The list of such classes can easily be
>     extended, but I have huge problems finding a lower bound to keep
>     this list
>     as small[1] as allowed according to the JVMS.
> 
>     Is there some part of the specification that states which classes
>     need to
>     be provided? I can only see references to the API (e.g. "reflective
>     APIs"),
>     but no clear definition of the classes that need to exist. In the
>     current
>     draft for JVMS 3rd edition, the necessity to include
>     java.io.Serializable
>     is not even part of the JVMS, this is only visible by looking at the
>     definition of arrays in the Java Language Specification (JLS).
> 
>     Some hints in this direction are also appreciated. So far I can only
>     guess,
>     that sun.awt.* is not part of the language defined in the JVMS - but who
>     knows?
> 
>     [1]: Sadly, just using whatever Sun or OpenJDK provide in rt.jar
>     does not
>     work.
> 
>     Thanks a lot,
>     --
>     Carsten Otto           otto at informatik.rwth-aachen.de
>     <mailto:otto at informatik.rwth-aachen.de>
>     LuFG Informatik 2      http://verify.rwth-aachen.de/otto/
>     RWTH Aachen            phone: +49 241 80-21211
> 
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>