Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

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6.1.2 The Adapter Pattern
Classes are often written to provide similar functionality to other classes. The
adapter design pattern applies to any context where we want to modify an existing
class so that its methods match those of a related, but different, class or interface.
One general way for applying the adapter pattern is to define the new class in such a
way that it contains an instance of the old class as a hidden field, and implement
each method of the new class using methods of this hidden instance variable. The
result of applying the adapter pattern is that a new class that performs almost the
same functions as a previous class, but in a more convenient way, has been created.
With respect to our discussion of the array list ADT, we note that this ADT is
sufficient to define an adapter class for the deque ADT, as shown in Table 6.1. (See
also Exercise C-6.8.)
Table 6.1:
array list.
Realization of a deque by means of an
Deque Method
Realization with Array-List Methods
size(), isEmpty()
size(), isEmpty()
getFirst()
get(0)
getLast()
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