php-java-bridge-users

[Php-java-bridge-users] "object is not an instance of declaring class"

[Thomas K. <tk...@da...>]

Hello everybody,

I'm trying to use the excellent jfree project JFreeChart
(http://www.jfree.org/jfreechart/index.php) to generate a few barcharts.

Unfortunately I get an error and don't know whats wrong.

Here's the code I use (as an example):



<?
java_require("jfreechart-1.0.0-rc1.jar");
$dataset = new Java("org.jfree.data.category.DefaultCategoryDataset");
print $dataset;
print $dataset->hashCode();
?>


This is what I get:

----------------- snip ---------------------------------------------
[class java.lang.String: First][class
org.jfree.data.category.DefaultCategoryDataset: class
org.jfree.data.category.DefaultCategoryDataset]

Fatal error: Uncaught [class java.lang.Exception: java.lang.Exception:
Invoke failed: [class
org.jfree.data.category.DefaultCategoryDataset]->hashCode. Cause:
java.lang.IllegalArgumentException: object is not an instance of
declaring class] thrown in /mnt/data/var/www/localhost/htdocs/java.php
on line 23
----------------- snap ---------------------------------------------

So apparantly, as to see in the first line, $dataset is indeed on object
of the class DefaultCategorySet.
But invoking a method on this object results in an error "object is not
an instance of declaring class".

What's wrong? Is this a bug in the bridge or did I do something wrong?

Thanks
Thomas

[Php-java-bridge-users] "object is not an instance of declaring class"

[Thomas K. <tk...@da...>]

Hello everybody,

I'm trying to use the excellent jfree project JFreeChart
(http://www.jfree.org/jfreechart/index.php) to generate a few barcharts.

Unfortunately I get an error and don't know whats wrong.

Here's the code I use (as an example, to provoce the error):



<?
java_require("jfreechart-1.0.0-rc1.jar");
$dataset = new Java("org.jfree.data.category.DefaultCategoryDataset");
print $dataset;
print $dataset->hashCode();
?>


This is what I get:

----------------- snip ---------------------------------------------
[class java.lang.String: First][class
org.jfree.data.category.DefaultCategoryDataset: class
org.jfree.data.category.DefaultCategoryDataset]

Fatal error: Uncaught [class java.lang.Exception: java.lang.Exception:
Invoke failed: [class
org.jfree.data.category.DefaultCategoryDataset]->hashCode. Cause:
java.lang.IllegalArgumentException: object is not an instance of
declaring class] thrown in /mnt/data/var/www/localhost/htdocs/java.php
on line 23
----------------- snap ---------------------------------------------

So apparantly, as to see in the first line, $dataset is indeed on object
of the class DefaultCategorySet.
But invoking a method on this object results in an error "object is not
an instance of declaring class".

What's wrong? Is this a bug in the bridge or did I do something wrong?

Thanks
Thomas

Ant: [Php-java-bridge-users] "object is not an instance of declaring class"

[Jost B. <jos...@ya...>]

Hi,

a extermal class is missing, so the bridge was not
able to invoke the constructor, it has returned the
class instead.  You should be able to locate the error
message in the bridge log file.


> So apparantly, as to see in the first line, $dataset
> is indeed on object

Objects are displayed as ...@hashCode, classes as
class:<name>.

But you're right that the message is not clear enough.
I will change the error message for the next version.

Your next question is probably what the
NoClassDefFoundError means, we have an open problem
report for this (it's a problem specific to the sun
platform, other platforms such as ecma335 and gnu java
don't have this problem).

Kai has already addressed one part of the problem with
his dynamic class loader which does not confuse
classes loaded from different url classloaders
anymore. However, the fundamental problem cannot be
fixed by us, this is something that sun must handle.

But it should be easy to avoid the problems if one
obeys the following rules:

* All interconnected classes must be accessible by the
same classloader.  This means that all interconnected
classes must be loaded by the same java_require()
call.  java_require(foo); java_require(bar); does not
work if foo and bar reference each other. This
condition stays the same unless you stop the bridge or
call java_reset(). (Reason is that even if you use
java_require(foo;bar) after that, the loader has
already cached the broken foo and the queries for bar
jump off from there).

* No class may be appear in more than java_require()
statement call within the same php script.


Regards,
Jost Boekemeier



	
		
___________________________________________________________ 
Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de