Information Technology Reference
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common to all subclasses, where the numerical integration rule is to be implemented
(in the subclasses):
class Integration
data:
prm
methods:
constructor(Integration_prm p)
prm=p
integrate()
Whenever appropriate, we insert the body of a function as indented statements under
the function heading.
The trapezoidal method is our first subclass candidate:
class Trapezoidal, subclass of Integration
data:
methods:
constructor(Integration_prm p)
Integration.constructor(p)
integrate()
h = (prm.b-prm.a)/(prm.npoints-1)
x=a
s=0
for i = 2,...,n-1
x=x+h
s=s+f(x)
s=s+0.5
*
(f(prm.a) + f(prm.b))
return h
*
s
This class apparently has data on its own, but it inherits the
prm
object from its base
class
Integration
, and no additional data are needed. The
constructor
passes
the
Integration prm
input object onto the base class constructor, which stores the
parameter object as the data member
prm
.Inthe
integrate
method, the integration
parameters are accessed through the
prm
object. For example,
prm.a
means the
a
data member of object
prm
. This is the same notation as used in common languages
supporting classes, such as C
CC
, Java, and Python.
6.5.4
A Class Hierarchy in Java
Readers who are familiar with the Java programming language will quite quickly
convert the previous pseudo code to Java. The following text is written for this group
of readers.
Thebaseclass
Integration
is realized as
class Integration {
public Integration_prm prm;
public Integration (Integration_prm p)
{prm=p;}
public double integrate ()
{
