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 Notice that, to within syntactical differences, the bodies of the base and inductive cases are identical between Scheme and Java implementations?

Why don't we need to know the exact type of rest?

Where Did The cond Go? 

 The Java implemenation enables us to clearly focus on and differentiate between the base and inductive cases by separating them into different sub-classes.  But where, you might ask, did the cond statement in the Scheme implementation go into the Java implementation?  

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This should not be surprising in that the cond statement was part of the invariant function template for all lists.    This tells us that differentiation between base and inductive cases is fundamental to the nature of lists.    Scheme is unable to express this fact in its structural representations of data, i.e. structs, so we were forced to represent it in terms of an invariant function template.    Java, however, has the ability to express this relationship in terms of its inheritance hierarchy and thus we use delegation to leverage this "polymorphic" behavior of the IntList sub-classes to let them differentiate themselves.

NO COND!!

 Exercises:

1. Add method to your lists classes that will calculate the product of all the elements.
2. Add a method to return a copy of your list.
3. Add methods to return the largest/smallest element of the list.   Integer.MAX_VALUE and Integer.MIN_VALUE are static fields of the Integer class that will give you the largest and smallest possible integer values in Java.

More List Exercises

A Scheme-like String representation of lists.

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