Description Luke Hutchison 2018-07-21 22:22:40 EDT

In the following code, the SubClass() constructor gives the compiler error "Unhandled exception type IOException". It is not obvious that this is coming from the superclass constructor ImplicitException(), because the error message doesn't say so. 

    import java.io.IOException;

    public class ImplicitException {
        public ImplicitException() throws IOException {
        }
    
        public static class SubClass extends ImplicitException {
            public SubClass() {   // "Unhandled exception type IOException"
            }
        }
    }

If you make the superclass constructor call explicit, the message makes sense, since it is given over the super() call, rather than at the top of the declaration of SubClass():


    import java.io.IOException;

    public class ImplicitException {
        public ImplicitException() throws IOException {
        }
    
        public static class SubClass extends ImplicitException {
            public SubClass() {
                super();         // "Unhandled exception type IOException"
            }
        }
    }

Whether or not the first line in SubClass is "super()", the superconstructor is called at the top of the SubClass constructor. But in the case that this call is implicit (in the top code example), the warning message needs to give the user more information, even by just adding the words "...in implicit call to default constructor of superclass".