Java Reference
In-Depth Information
■
A private
int
data field named
speed
that specifies the speed of the fan (the
default is
SLOW
).
■
A private
boolean
data field named
on
that specifies whether the fan is on (the
default is
false
).
■
A private
double
data field named
radius
that specifies the radius of the fan
(the default is
5
).
■
A string data field named
color
that specifies the color of the fan (the default
is
blue
).
■
The accessor and mutator methods for all four data fields.
■
A no-arg constructor that creates a default fan.
■
A method named
toString()
that returns a string description for the fan. If
the fan is on, the method returns the fan speed, color, and radius in one com-
bined string. If the fan is not on, the method returns the fan color and radius
along with the string “fan is off ” in one combined string.
Draw the UML diagram for the class and then implement the class. Write a test
program that creates two
Fan
objects. Assign maximum speed, radius
10
, color
yellow
, and turn it on to the first object. Assign medium speed, radius
5
, color
blue
, and turn it off to the second object. Display the objects by invoking their
toString
method.
**8.9
(
Geometry: n-sided regular polygon
) In an
n
-sided regular polygon, all sides have
the same length and all angles have the same degree (i.e., the polygon is both equi-
lateral and equiangular). Design a class named
RegularPolygon
that contains:
■
A private
int
data field named
n
that defines the number of sides in the poly-
gon with default value
3
.
■
A private
double
data field named
side
that stores the length of the side with
default value
1
.
■
A private
double
data field named
x
that defines the
x
-coordinate of the poly-
gon's center with default value
0
.
■
A private
double
data field named
y
that defines the
y
-coordinate of the poly-
gon's center with default value
0
.
■
A no-arg constructor that creates a regular polygon with default values.
■
A constructor that creates a regular polygon with the specified number of sides
and length of side, centered at (
0
,
0
).
■
A constructor that creates a regular polygon with the specified number of sides,
length of side, and
x
-and
y
-coordinates.
■
The accessor and mutator methods for all data fields.
■
The method
getPerimeter()
that returns the perimeter of the polygon.
■
The method
getArea()
that returns the area of the polygon. The formula for
s
2
n
*
computing the area of a regular polygon is
Area
=
.
n
≤
4
*
tan
¢
Draw the UML diagram for the class and then implement the class. Write a test
program that creates three
RegularPolygon
objects, created using the no-arg
constructor, using
RegularPolygon(6, 4)
, and using
RegularPolygon(10,
4, 5.6, 7.8)
. For each object, display its perimeter and area.
*8.10
(
Algebra: quadratic equations
) Design a class named
QuadraticEquation
for a
quadratic equation
ax
2
+
bx
+
x
=
0.
The class contains:
■
Private data fields
a
,
b
, and
c
that represent three coefficients.
■
A constructor for the arguments for
a
,
b
, and
c
.