When trying to load an array class in certain situations where a checked
ClassNotFoundException should be thrown if the class cannot be found, an
unchecked NoClassDefFoundError will be thrown instead. This will happen, for
example, when using Class.forName, or when deserializing an array of a class
that must be loaded. This is because while the internal runtime function
FindClassFromClass2 takes an boolean argument to specify whether to throw a
ClassNotFoundException or a NoClassDefFoundError on failure to *find* the class,
it does not pass this information on when it needs to find the class of a
desired array classes element type.

I brought this issue up with Sheng a few weeks ago, and he agreed that it is a
problem that should be fixed. The e-mail correspondence is included below.

There is also a test case that is attached. Although it is not the most
compelling test case, it is extremely simple. A more compelling example would
be an RMI application that needs to pass arrays of a loaded class using
serialization.


From jones@terrier Mon Aug 11 00:30:19 1997
From: jones@terrier (Peter Jones - JavaSoft East )
To: sheng.liang@eng
Subject: FindClassFromClass2 throwing NoClassDefFoundError
Cc: ann@terrier, jones@terrier, riggs@terrier
 
Hi Sheng,
 
As you suggested a few weeks ago, changing the relevant class loading
code in serialization to use FindClassFromClass2 with FALSE for the
throwError parameter took care of most of the cases where it was
getting a NoClassDefFoundError inappropriately.
 
The error still always gets thrown for array classes, however, because
the FindArrayClassFromClass() function does not pass its caller's
throwError argument down when it calls FindClassFromClass() to find the
element type class. I think that if the caller wanted to get a
ClassNotFoundException instead of an error when trying to find a class,
that should remain true even if he's trying to find an array class.
The throwError argument could simply be passed down to
FindArrayClassFromClass() which would forward it on when it calls back
to FindClassFromClass2(). Do you agree? I have tested this with the
following simple diffs to classresolver.c, and it solves the
NoClassDefFoundError I was getting:
 
 
[terrier]<peter> 144 % sccs diffs classresolver.c
 
------- classresolver.c -------
59c59,60
< ClassClass *from);
---
> ClassClass *from,
> bool_t throwError);
936c937
< cb = FindArrayClassFromClass(ee, name, from) ;
---
> cb = FindArrayClassFromClass(ee, name, from, throwError);
1031c1032
< ClassClass *from) {
---
> ClassClass *from, bool_t throwError) {
1085c1086
< inner_cb = FindClassFromClass(ee, buffer, FALSE, from);
---
> inner_cb = FindClassFromClass2(ee, buffer, FALSE, from, throwError);
 
 
-- Peter
 
From Sheng.Liang@Eng Mon Aug 11 02:25:36 1997
From: Sheng.Liang@Eng (Sheng Liang)
To: ###@###.###, sheng.liang@Eng
Subject: Re: FindClassFromClass2 throwing NoClassDefFoundError
Cc: ###@###.###, ###@###.###
 
> The error still always gets thrown for array classes, however, because
> the FindArrayClassFromClass() function does not pass its caller's
> throwError argument down when it calls FindClassFromClass() to find the
> element type class.
 
I agree with your analysis. This is an oversight. I'll fix it.
 
Sheng