Help: ContextClassLoader in jtreg tests

[Weijun Wang]

On 08/08/2011 10:46 AM, David Holmes wrote:
> Hi Max,
>
> Weijun Wang said the following on 08/06/11 00:19:
>> I have two files: A.java and B.java
>>
>> /*
>> * @test
>> * @build A B
>> * @run main A
>> */
>> public class A {
>> public static void main(String[] args) throws Exception {
>> Class.forName("B", true, Thread.currentThread().getContextClassLoader());
>> }
>> }
>>
>> public class B {
>> }
>>
>> Now jtreg A.java shows:
>>
>> java.lang.ClassNotFoundException: B
>>
>> How can I get B visible in A's ContextClassLoader?
>
> It isn't A's context class loader it is the current threads. If the
> above isn't working then either:
>
> a) A is not being loaded by the application (aka system) classloader
> (jtreg is using a custom loader); or
> b) jtreg has explicitly changed the current thread's context classloader
>
> You would need to investigate what A.class.getClassLoader() reports, and
> what Thread.currentThread().getContextClassLoader() reports.

A.class.getClassLoader(): A URLClassLoader looking at 
JTwork/classes/test_location and $TESTSRC.

Thread.currentThread().getContextClassLoader(): A 
sun.misc.Launcher$AppClassLoader looking at jtreg.jar. It is also the 
parent class loader of A.class.getClassLoader().

BTW, I've added

             Thread.currentThread().setContextClassLoader(
                     A.class.getClassLoader());

to the test to make it pass.

>
>> Don't tell me to change to Class.forName("B"), that line is copied
>> from JDK that is called by a real test.
>>
>> Or, the JDK code itself is problematic and it should fallback to
>> another ClassLoader?
>
> It's unclear why the code/test needs to use the context classloader here
> (or why/how it knows the context loader is the correct loader).

I'm not sure.

Thanks
Max

>
> Cheers,
> David
>
>> Thanks
>> Max