Question

This is on Java 6

Can I have a common method to handle my exceptions – so instead of doing this n times in each method

try {
    // Do something
} catch (XException e) {
    // Do something
} catch (YException e) {
    // Do something
} catch (ZException e) {
    // Do something
}

I have

try {
        // Do something
    } catch (Exception e) {
        handleAll (e);
    }

and method handleAll(e) does

if e.instanceOf(XException)

else if e.instanceOf(YException)

else if e.instanceOf(ZException)

Is there anything wrong with the 2nd approach?

Update:

My original question was about “centralizing the handling” in one place for both checked and runtime exceptions. The answers have pointed out I should avoid instanceof().

@aioobe’s idea looks very neat to me. Are there any negative opinions on that approach?

Answer 1

There is one minor problem as I see it. Since you really want the handleAll method to rethrow any uncaught exception, it has to be declared throws Exception. This means that so does the methods that call handleAll.

If X-, Y- and ZException are all RuntimeExceptions I see nothing wrong with this. (I may have overlooked something though, as this is the first time I’ve seen this approach.)

To be sure that the instanceof approach behaves exactly as the catch clauses would, I would consider designing the handleAll(RuntimeException e) like this though:

private void handleAll(RuntimeException e) {
    try {
        throw e;
    } catch (XException xe) {
        ...
    } catch (YException xe) {
        ...
    } catch (ZException xe) {
        ...
    }
}