Generic Types - The Java Programming Language - page 375

you, an array of the right size and typewhich we show you a little lateror
you could have the caller provide the type token for E (the Class object
for the actual type argument) and use reflection to create an array of
the right sizesee " Genericity and Dynamic Arrays " on page 430 .
Exercise 11.1 : Revisit the LinkedList class that you started back in Ex-
ercise 2.2 and rewrite it as a generic class.
Exercise 11.2 : Rewrite the Attr class from Chapter 3 as a generic class.
Exercise 11.3 : Was Exercise 11.2 a good idea? How does Attr being
generic affect the Attributed interface defined in Chapter 4 ? What does
it mean for Attributed objects?
11.1.1. Bounded Type Parameters
In the generic class declaration of Cell<E> , the type variable E can be
replaced by absolutely any reference type. Sometimes it doesn't make
sense to allow an arbitrary type argument to be used with a generic
type. For example, a sorted collection can hold any type of object as
long as that object can be sorted. As you have seen a number of times
now, the way to define something that can be sorted is to have it im-
plement the Comparable interface. Comparable itself is a generic interface,
with a single type variable that identifies what type the current type can
be compared with. Usually, objects of a given type should only be com-
pared with other objects of that same type, so typically a class Value
that is comparable will be declared as
class Value implements Comparable<Value> {
// ...
}
So a sorted collection would restrict its type parameter to be a type that
implements Comparable : [2]