Question

Given this code,

Collection<?> callables = ...
ExecutorService executorService = ...
List<Future<?>> futures = executorService.invokeAll(callables, TIMEOUT, TimeUnit.SECONDS);

I’d like to know which of the callables were cancelled (did not finish in time). I know I can query each Future with .isCancelled() but that gives me no information as to which exact Callable was cancelled.

One solution would be for Future to implement a toString() method that delegates to the underlying toString() of Callable. Unfortunately, this is not done.

Answer 1

I know I can query each Future with .isCancelled() but that gives me no information as to which exact Callable was cancelled.

The list of Futures is in the same order as the list of Callables it was created from. So you can keep track that way.