Lambda and multi-catch

[Gustav Åkesson]

Hi,

I too was a bit confused by the example. :-)

I assume this nasty bug is already registered?

Best regards,
Gustav Åkesson
Den 7 mar 2014 07:17 skrev "David Holmes" <david.holmes at oracle.com>:

> On 7/03/2014 3:53 PM, Sam Pullara wrote:
> > It is throwing an NPE when he dereferences the null o -- I thought the
> > same thing the first time I looked at it.
>
> Ughhh. That was unnecessarily obscure.
>
> So the issue is that use of Exception is catching exceptions it should not.
>
> Thanks Sam.
>
> David
>
> > Sam
> >
> >
> >
> > On Thu, Mar 6, 2014 at 9:15 PM, David Holmes <david.holmes at oracle.com
> > <mailto:david.holmes at oracle.com>> wrote:
> >
> >     On 6/03/2014 9:29 PM, Remi Forax wrote:
> >      > A colleague of mine have find a hairy bug,
> >      > here is a simple code to reproduce it.
> >      >
> >      > import java.io.IOException;
> >      >
> >      > public class FunWithMultiCatch {
> >      >     public static void main(String[] args) {
> >      >       Runnable r = () -> {
> >      >         try {
> >      >           Object o = null;
> >      >           o.getClass();
> >      >           throw new IOException();
> >      >         } catch(IOException | IllegalArgumentException e) {
> >      >           System.out.println("KO !");
> >      >         } catch(RuntimeException e) {
> >      >           System.out.println("OK !");
> >      >         }
> >      >       };
> >      >       r.run();
> >      >     }
> >      > }
> >      >
> >      > It prints 'KO !' :(
> >
> >     What am I missing? We throw IOException and have a catch block for
> >     IOException so I would expect it to print "KO !".
> >
> >     I'm more surprised that a non-lambda version prints "OK !"
> >
> >      > The problem can be reproduced for any multi-catch inside a lambda,
> >      > the exception table is clearly wrong, the IOException and IAE are
> >     merged
> >      > to their common supertype (java.lang.Exception).
> >
> >     That would definitely seem wrong, but more of an issue with catching
> >     RuntimeExceptions in the first block that should be handled by the
> >     second catch block. eg change it to throw IllegalStateException()
> >     instead:
> >
> >     if (false) throw new IOException();
> >     throw new IllegalStateException();
> >
> >     -> "KO !"   !!!WT!
> >
> >     David
> >     -----
> >
> >      > private static void lambda$main$0();
> >      >       Code:
> >      >          0: aconst_null
> >      >          ...
> >      >         14: athrow
> >      >         15: astore_0
> >      >         16: getstatic     #8                  // Field
> >      > java/lang/System.out:Ljava/io/PrintStream;
> >      >         19: ldc           #9                  // String OK !
> >      >         21: invokevirtual #10                 // Method
> >      > java/io/PrintStream.println:(Ljava/lang/String;)V
> >      >         24: goto          36
> >      >         27: astore_0
> >      >         28: getstatic     #8                  // Field
> >      > java/lang/System.out:Ljava/io/PrintStream;
> >      >         31: ldc           #12                 // String KO !
> >      >         33: invokevirtual #10                 // Method
> >      > java/io/PrintStream.println:(Ljava/lang/String;)V
> >      >         36: return
> >      >       Exception table:
> >      >          from    to  target type
> >      >              0    15    15   Class
> >      > java/lang/Exception                            <------------ Oops
> >      >              0    15    27   Class java/lang/RuntimeException
> >      >
> >      > The current workaround is to not use a multi-catch in a lambda.
> >      >
> >      > It seems that some version of Eclipse had the same issue but it's
> >     fixed
> >      > with the one I use (from 21 feb).
> >      >
> >      > cheers,
> >      > Rémi
> >      >
> >      >
> >
> >
>
>