Handling exceptions from Java ExecutorService tasks

WARNING: It should be noted that this solution will block the calling thread.


If you want to process exceptions thrown by the task, then it is generally better to use Callable rather than Runnable.

Callable.call() is permitted to throw checked exceptions, and these get propagated back to the calling thread:

Callable task = ...
Future future = executor.submit(task);
try {
   future.get();
} catch (ExecutionException ex) {
   ex.getCause().printStackTrace();
}

If Callable.call() throws an exception, this will be wrapped in an ExecutionException and thrown by Future.get().

This is likely to be much preferable to subclassing ThreadPoolExecutor. It also gives you the opportunity to re-submit the task if the exception is a recoverable one.

Leave a Comment