Time to put a stop to Thread.stop?

[David Holmes]

On 29/05/2013 11:23 AM, Martin Buchholz wrote:
> [+compiler-dev]
>
>
> On Wed, May 15, 2013 at 1:05 AM, David Holmes <david.holmes at oracle.com>wrote:
>
>> On 15/05/2013 3:16 PM, Martin Buchholz wrote:
>>
>>>
>>>
>>> General purpose library code sometimes would like to rethrow an
>>> exception that was previously caught.
>>> How should it do that?
>>>
>>
>> Umm catch it and throw it. If it is a checked-exception that you want to
>> propogate then you should have declared it on your method, else you are
>> going to wrap it in a runtime exception or error. There is no need for such
>> sleaze.
>>
>>
> Taking a closer look at one use of Thread.stop, I see that we use it to
> throw a Throwable out of Callable.call.  Which I think we should be able to
> do.  But I can't.

Why do you think you should be able to throw an arbitrary Throwable from 
Callable.call?

>   cat CallableThrow.java && javac CallableThrow.java
>
> public class CallableThrow {
>      public static void main(String[] args) throws Throwable {
>          final Throwable t = new Throwable();
>          new java.util.concurrent.Callable<Void>() {
>              public Void call() throws Exception { throw t; }};
>      }
> }
> CallableThrow.java:5: error: unreported exception Throwable; must be caught
> or declared to be thrown
>              public Void call() throws Exception { throw t; }};
>                                                    ^
> 1 error
>
>
> If I change Exception to Throwable I get:
>
> public class CallableThrow {
>      public static void main(String[] args) throws Throwable {
>          final Throwable t = new Throwable();
>          new java.util.concurrent.Callable<Void>() {
>              public Void call() throws Throwable { throw t; }};
>      }
> }
> CallableThrow.java:5: error: call() in <anonymous CallableThrow$1> cannot
> implement call() in Callable
>              public Void call() throws Throwable { throw t; }};
>                          ^
>    overridden method does not throw Throwable
>    where V is a type-variable:
>      V extends Object declared in interface Callable
> 1 error

All correct. You can't do this.

David