Question

How should I handle InterruptedException while joining other threads, assuming I don’t actually anticipate being interrupted, and there is no sensible thing to do? Just swallow the exception?

try
{
    t.join();
    u.join();
}
catch (InterruptedException e)
{
    // should not happen
}

Or should I put each join in its separate try/catch, so if an InterruptedExeption does happen while joining t, at least u gets a chance of being joined?

try
{
    t.join();
}
catch (InterruptedException e)
{
    // should not happen
}
try
{
    u.join();
}
catch (InterruptedException e)
{
    // should not happen
}

Or should I defensively swallow the exceptions in a loop, so I will eventually join both threads, even if some malicious guy tries to interrupt me?

while (true)
{
    try
    {
        t.join();
        break;
    }
    catch (InterruptedException e)
    {
        // no way, Jose!
    }
}
while (true)
{
    try
    {
        u.join();
        break;
    }
    catch (InterruptedException e)
    {
        // no way, Jose!
    }
}

On a side note, is there any case where InterruptedExeption doesn’t make my code look ugly? 🙂

Answer 1

If something shouldn’t happen, you probably want to know if it ever does happen – and the best way of making it obvious is often to throw a RuntimeException of some description (e.g. IllegalStateException). If you’re not anticipating the possibility of being interrupted, that suggests the system is in a state you’re not really happy to support, so I wouldn’t then try to keep going – aborting quickly is often the best option here.

You may want to write a helper method which does this for you, to make the calling code cleaner.