I have a method with a checked exception for a parent class, which can throw exceptions of the type parent and subclass
public void method() throws ParentException {
if( false ) throw new ParentException();
else if( true ) throw new ChildException(); // this one is thrown
}
and I have a cascade catch block, which first has the child exception
try {
method();
} catch (ChildException e) {
// I get here?
} catch (ParentException e) {
// or here?
}
Which block will catch the exception thrown? Since the method declares explicitly the ParentException only, would the ChildException be shown as an instance of ParentException?
The
catch
block will always catch the most specific exception available to it, working its way up from the inheritance hierarchy.I should stress that your catch blocks must be in the inheritance hierarchy order; that is to say, you may not declare a
catch
block withParentException
followed byChildException
, as that is a compilation error. What you have there (in terms ofcatch
blocks) is valid.A more common use case of this is when handling file IO; you can first catch
FileNotFoundException
, thenIOException
, should the error be less specific thanFileNotFoundException
.