Exceptions: Future.get wraps a task's exception in ExecutionException

When a task submitted to an ExecutorService throws, calling get() on its Future does not rethrow that exception directly; it wraps it inside an ExecutionException whose getCause holds the real failure.

Code

ExecutorService pool = Executors.newSingleThreadExecutor();
Future<Integer> future = pool.submit(() -> {
    throw new ArithmeticException("task failed");
});
try {
    future.get();
} catch (ExecutionException e) {
    System.out.println(e.getClass().getSimpleName() + " caused by " + e.getCause().getClass().getSimpleName() + ": " + e.getCause().getMessage());
} catch (InterruptedException e) {
    Thread.currentThread().interrupt();
} finally {
    pool.shutdown();
}

Output

ExecutionException caused by ArithmeticException: task failed