Errata 6

From APIDesign

Page 89

The chapter 6 discusses protected abstract methods and says that removing such method is source compatible. In fact that was true until Java 5 appeared. However the newly introduced @Override annotation changed everything.

does not exists: anagram.ui.Anagrams

If you create a new version of public abstract class Anagrams dropping either getWordLibrary or getScrambler (or both), the @Override annotation in AnagramsWithConstructor will cause the compiler to complain:

does not exists: anagram.ui.init

Source compatibility is gone. As an API designer of public class Anagrams you don't know whether your users (writing class AnagramsWithConstructor) will use @Override. As a result don't even try to remove protected abstract methods from an API. It was never good idea anyway and since Java 5 it is not backward compatible.

-- Rijk van Haaften, Oct 8, 2010

Page 90

In the example of defining inserting new super class into existing class hierarchy, the whole source code should have been shown. The newly created SimpleHelloClass should define no argument method. The original HelloClass shall extend it and keep definition of the more complicated sayHelloTo method with one string argument:

does not exists: design.insert.superclass1

does not exists: design.insert.superclass2

Cordeo 21:47, 7 October 2010 (UTC)