An Integer List
Example 2-7 is a class
that implements a list or growable array of int values. This IntList class is like the java.util.ArrayList class, but it works with
primitive int values rather than
objects. When you need to store int
values and do not know the number of values in advance (i.e., you
can’t use an array), IntList is
much more efficient than using an ArrayList because there is no need to wrap
your int values in Integer objects. The interesting thing about
this example is not its efficiency, however, but the fact that it is a
real-world example: the code is nontrivial but easy to understand, and
the class actually serves a useful purpose.
Also interesting is the fact that this class overrides a number
of methods inherited from Object in
order to provide meaningful implementations. Like the ComplexNumber class of Example 2-5, this class defines a
toString( ) method to convert its
state to a textual representation that can be displayed in log
messages, debugging statements, and elsewhere. Additionally, it
overrides the equals( ) method to
determine if two IntList objects
are equal. It also overrides the hashCode(
) method to provide a compatible implementation that ensures
that IntList objects that are equal
have the same hash code. This enables IntList objects to be used as keys in
hashtables such as the java.util.HashMap class.
The Object class also defines
the clone( ) or finalize( )
methods, but neither method is recommend for general
use, and IntList does ...
Get Java Examples in a Nutshell, 3rd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
