Unit #8:
Classes and Objects in Java
Problem #1:
The programs
below implement the following:
1)
Rectangle.java implements a Rectangle class as specified below (see
private variables and public methods below)
2)
RectangleTest.java creates an instance (or object)
of the Rectangle class and calls all
the public methods
Private Variables:
The class
will contain two integer private variables – length and width
Public Methods:
a)
The class
has two constructors:
o
Constructor#1:
a default constructor, Rectangle ()
which sets the length = 0 and width = 0
o
Constructor
#2: a parameter constructor, Rectangle
(int a, int b) which sets the length
= a and width = b, where a and b are specified input values
b)
public int getLength() : returns the length of the
rectangle
c)
public int getWidth() : returns the width of the
rectangle
d)
public void setLength(int
a) : sets the
length of the rectangle to equal the
input value, a (specified by the
user)
e)
public void setWidth
(int b): sets the
width of the rectangle to equal the input value, b (specified by the user)
f)
public int getArea() : computes and returns the area
of the rectangle
Object view
of the Class:
Program Code
Program Output:
Length of
the Rectangle = 10
Width of the
Rectangle = 12
Area of the
Rectangle = 120
Changing the
length and width of the Rectangle:
Input Length
34
Input Width
23
Area = 782
Problem #2:
The programs
below implement the following:
1)
Rectangle.java implements a Rectangle class as specified above.
2)
RectangleTestArray.java implements the following:
a.
Creates an
array (of input size) of type Rectangle.
b.
Creates and
stores an instance of the Rectangle
class for every cell in the array
c.
Takes
integer input values for length and width for every Rectangle object in the array
d.
Computes the
area for every Rectangle object in
the array
· Program Code
Program Output:
ow many
rectangles do you want to create?
3
Input length
for Rectangle
1
Input width
for Rectangle
2
Area of
Rectangle = 2
Input length
for Rectangle
3
Input width
for Rectangle
4
Area of
Rectangle = 12
Input length
for Rectangle
5
Input width
for Rectangle
6
Area of
Rectangle = 30
