I was actually interested in the thrust of the original question, let me
rephrase it.
If you wanted to code from scratch a JVM, but not include the rest of
the Java SE platform (such as the .class files), what would you need to
include? Is Object.class mandatory for a pure JVM? Anything else?
The answers given imply that the JVM is not an isolated well defined
component. Yet that argues against being able to write a new programming
language for the JVM that has no integration whatsoever with the Java
language and just emits 'pure bytecode' for a 'pure JVM'.
I, like Carsten, find it odd if this isn't well-defined.
Stephen
David Holmes - Sun Microsystems wrote:
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
<o...@informatik.rwth-aachen.de
<mailto:o...@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 o...@informatik.rwth-aachen.de
<mailto:o...@informatik.rwth-aachen.de>
LuFG Informatik 2 http://verify.rwth-aachen.de/otto/
RWTH Aachen phone: +49 241 80-21211
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