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_Mario_ - 05 Dec 2004 16:39 GMT

Hi all,

I've got a class Figure in my project.

Figure is an Abstract class.

I need to know all the names of the classes present in the package that
extends/implement Figure.

How can I do to do this from my MainClass (that is not Figure)????

Thanks a lot.

Mario

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Stefan Schulz - 05 Dec 2004 19:49 GMT

> Hi all,
>
[quoted text clipped - 6 lines]
>
> How can I do to do this from my MainClass (that is not Figure)????

Not at all.

What if you call the hypothetical "getChildren" method, and two
milliseconds
later some other thread calls defineClass() for yet another child class?

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_Mario_ - 05 Dec 2004 20:59 GMT

>> Hi all,
>>
[quoted text clipped - 12 lines]
> milliseconds
> later some other thread calls defineClass() for yet another child class?

No thread can do this....

anyway: how can I find all the class that extends my class Figure?

Mario

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Ryan Stewart - 05 Dec 2004 21:51 GMT

[...]

>>> I need to know all the names of the classes present in the package that
>>> extends/implement Figure.
>>>
>>> How can I do to do this from my MainClass (that is not Figure)????
>>
>> Not at all.

[...]

> anyway: how can I find all the class that extends my class Figure?

Try reading Stefan's post again (important part above). You can't. ... But
then, theoretically, I supposed you could run javadoc on your project, parse
the output for that class and try to get subclasses from that.

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_Mario_ - 06 Dec 2004 00:31 GMT

> [...]
>>>> I need to know all the names of the classes present in the package that
[quoted text clipped - 10 lines]
> then, theoretically, I supposed you could run javadoc on your project,
> parse the output for that class and try to get subclasses from that.

OK thanks

Mario

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Iain Robinson - 06 Dec 2004 00:41 GMT

> Hi all,
>
[quoted text clipped - 8 lines]
>
>...

Hi,

I dont want to go against what everyone else has said on this - since
i'm no Java expert - but if you meant "implements" (not - i think -
extends - but then again..) wouldn't this be possible to do using the
Class.getInterfaces() method?

The way i'm thinking is this... if you know each class will be in the
same package then it must be in the same directory...you could create an
instance of each class in that directory and call this method for each one.

I'm not saying that this would be safe in all circumstances but it might
be suitable in some (although a bit of a work-around for possibly little
benefit...i don't know).

comments please

P@

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Chris Smith - 09 Dec 2004 20:02 GMT

> I dont want to go against what everyone else has said on this - since
> i'm no Java expert - but if you meant "implements" (not - i think -
[quoted text clipped - 8 lines]
> be suitable in some (although a bit of a work-around for possibly little
> benefit...i don't know).

If you could get a list of all classes that *might* extend or implement
a given type, then yes it would become possible. However, you can't do
that. There is no way to get a list of all the classes in the system,
or in a package, or anything.

If you only want classes from the system classloader, though, then you
could walk through all the paths in the "java.class.path" system
property and look for classes; but you'll get some that didn't exist
(i.e., weren't loaded into the VM) until you looked for them. If all
these limitations are okay, then you have a kludgy answer.

Alternatively, if you're attempting to write a development tool, look
into the JVMTI (or pre 1.5, the JVMPI or JVMDI).

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