but your version has the disadvantage of being visible
i (and i hope christian too) was hoping for a more magical way of
throwing checked exceptions
of course you shouldnt use those in an actual app
On Wed, Aug 26, 2009 at 5:36 AM, Reinier Zwitserloot<reini...@gmail.com> wrote:
>
> WTF? I already posted a much better version of this in the
> supermegauber thread. no need for class file hacking. sun.misc.Unsafe
> is an even worse idea (Security Manager issues, as well as a
> dependency on running in sun VMs).
>
> public class SneakyThrow {
> public static RuntimeException sneakyThrow(Throwable t) {
> if ( t == null ) throw new NullPointerException("t");
> SneakyThrow.<RuntimeException>sneakyThrow0(t);
> return null;
> }
>
> �...@suppresswarnings("unchecked")
> private static <T extends Throwable> void sneakyThrow0(Throwable t)
> throws T {
> throw (T)t;
> }
> }
>
>
> Note also how this is much more thought through: Java does not know
> that calling this method automatically triggers a throw statement, so
> the compiler will whine that you need to return something, and the DA
> rules are all messed up. Therefore, the suggested usage is:
>
> public int myMethod() {
> throw sneakyThrow(new IOException());
> }
>
> Note the 'throw' in front of 'sneakyThrow'. If you've read up on your
> JLS and JVMS, you'll know that this code is perfectly valid java (and,
> given sun's dogged adherence to backwards compatibility, should mean
> it'll continue to work just fine), and that it'll work on every java-
> compatible VM.
>
> On Aug 26, 5:54 am, Christian Catchpole <christ...@catchpole.net>
> wrote:
>> Yeah, i was reading about that one. But it's only in the Sun VMs and
>> probably subject to change.
>>
>> But hey, I just listed this as an exercise. It just shows the
>> difference between checked and unchecked is one little byte. :)
>>
>> On Aug 26, 1:44 pm, Marcelo Fukushima <takesh...@gmail.com> wrote:
>>
>>
>>
>> > theres also a throwException(Throwable) in sun.misc.Unsafe - though to
>> > use that you really have to want to
>>
>> > On Wed, Aug 26, 2009 at 12:30 AM, Christian
>>
>> > Catchpole<christ...@catchpole.net> wrote:
>>
>> > > Compile this.. (any package you like, or no package at all)
>>
>> > > public class Rethrow {
>> > > public static void unchecked(Throwable t) {
>> > > t=t;
>> > > }
>> > > }
>>
>> > > javap reports the byte code as..
>>
>> > > public static void unchecked(java.lang.Throwable);
>> > > Code:
>> > > Stack=1, Locals=1, Args_size=1
>> > > 0: aload_0
>> > > 1: astore_0
>> > > 2: return
>>
>> > > which in hex is:
>>
>> > > 2A 4B B1
>>
>> > > open the class file in the hex editor, search for that and change it
>> > > to:
>>
>> > > 2A BF B1
>>
>> > > javap now reports the byte code as..
>>
>> > > public static void unchecked(java.lang.Throwable);
>> > > Code:
>> > > Stack=1, Locals=1, Args_size=1
>> > > 0: aload_0
>> > > 1: athrow
>> > > 2: return
>>
>> > > jar that class up or otherwise protect it from re-write.
>>
>> > > In your code you can now call this without wrapping with a runtime
>> > > exception. And the stack trace is still that of the original
>> > > exception.
>>
>> > > } catch(Exception e) {
>> > > Rethrow.unchecked(e);
>> > > }
>>
>> > > Obviously, use at your own risk. No warrenties etc. :)
>>
>> > --http://mapsdev.blogspot.com/
>> > Marcelo Takeshi Fukushima
> >
>
--
http://mapsdev.blogspot.com/
Marcelo Takeshi Fukushima
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