How can I throw CHECKED exceptions from inside Java 8 streams?

Question

How can I throw CHECKED exceptions from inside Java 8 streams/lambdas?

In other words, I want to make code like this compile:

public List

        

Answer 1

I use this kind of wrapping exception:

public class CheckedExceptionWrapper extends RuntimeException {
    ...
    public  CheckedExceptionWrapper rethrow() throws T {
        throw (T) getCause();
    }
}

It will require handling these exceptions statically:

void method() throws IOException, ServletException {
    try { 
        list.stream().forEach(object -> {
            ...
            throw new CheckedExceptionWrapper(e);
            ...            
        });
    } catch (CheckedExceptionWrapper e){
        e.rethrow();
        e.rethrow();
    }
}

Try it online!

Though exception will be anyway re-thrown during first rethrow() call (oh, Java generics...), this way allows to get a strict statical definition of possible exceptions (requires to declare them in throws). And no instanceof or something is needed.