Description
Overview: You will write a program this week that is composed of two classes: (1) one
named Trapezohedron that defines Trapezohedron objects, and (2) the other,
TrapezohedronApp, which has a main method that reads in data, creates an Trapezohedron
object, and then prints the object.
A pentagonal trapezohedron (or a pentagonal deltohedron) is a polyhedron composed of 10
kites as faces (with side lengths a and b), 20 edges, and 12 vertices. The formulas are provided
to assist you in computing return values for the respective methods in the Trapezohedron class
described in this project.
(Sources: https://en.wikipedia.org/wiki/Pentagonal_trapezohedron#10-sided_dice
https://rechneronline.de/pi/trapezohedron.php) To use calculator, see Test paragraph on page 5.
Formulas for edge length antiprism (z), long edge length (b),
surface area (A), and volume (V) are shown below where � is the
short edge length, which will be read in.
� = �⁄(( √5 − 1)/2)
� = ((√5 + 1)/2) ∗ �
� = 225
2.0
∗ (5 + √5) ∗ �!
� = 5.0
12
∗ 63 + √58 ∗ �”
b
a
�
Project: Trapezohedron App Page 2 of 5
Page 2 of 5
• Trapezohedron.java
Requirements: Create an Trapezohedron class that stores the label, color, and short edge
length, which must be non-negative. The Trapezohedron class also includes methods to
set and get each of these three fields, as well as methods to calculate the edge length
antiprism, the long edge length, surface area, and volume of the Trapezohedron object,
and a method to provide a String value of an Trapezohedron object (i.e., a class instance).
Design: The Trapezohedron class has fields, a constructor, and methods as outlined
below.
(1) Fields (instance variables): label of type String, color of type String, and short edge
of type double. Initialize the Strings to “” and the double to zero in their respective
declarations. These instance variables should be private so that they are not directly
accessible from outside of the Trapezohedron class, and these should be the only
instance variables in the class.
(2) Constructor: Your Trapezohedron class must contain a public constructor that accepts
three parameters (see types of above) representing the label, color, and short edge. Instead of
assigning the parameters directly to the fields, the respective set method for each field
(described below) should be called. For example, instead of the statement label =
labelIn; use the statement setLabel(labelIn); Below are examples of how the
constructor could be used to create Trapezohedron objects. Note that although String and
numeric literals are used for the actual parameters (or arguments) in these examples, variables
of the required type could have been used instead of the literals.
Trapezohedron ex1 = new Trapezohedron (“Ex 1”, “red”, 5.0);
Trapezohedron ex2 = new Trapezohedron (” Ex 2 “, “blue”, 10.4);
Trapezohedron ex3 = new Trapezohedron (“Ex 3”, “red, blue, tan”, 24.5);
(3) Methods: Usually a class provides methods to access and modify each of its instance
variables (known as get and set methods) along with any other required methods.
The methods for Trapezohedron, which should each be public, are described below.
See formulas in Code and Test below.
o getLabel: Accepts no parameters and returns a String representing the label
field.
o setLabel: Takes a String parameter and returns a boolean. If the string
parameter is not null, then the label field is set to the “trimmed” String and the
method returns true. Otherwise, the method returns false and the label field is not
set.
o getColor: Accepts no parameters and returns a String representing the color field.
o setColor: Takes a String parameter and returns a boolean. If the string
parameter is not null, then the “trimmed” String is set to the color field and the
method returns true. Otherwise, the method returns false and the label is not set.
Project: Trapezohedron App Page 3 of 5
Page 3 of 5
o getShortEdge: Accepts no parameters and returns a double representing the
short edge field.
o setShortEdge: Accepts a double parameter and returns a boolean as follows.
If the short edge is greater than zero, sets the short edge field to the double passed
in and returns true. Otherwise, the method returns false and the short edge is not
set.
o edgeLengthAntiprism: Accepts no parameters and returns the double value
for the edge length antiprism calculated using the value for short edge (a) in the
formula above.
o longEdge: Accepts no parameters and returns the double value for the long
edge calculated using the formula above.
o surfaceArea: Accepts no parameters and returns the double value for the
surface area calculated using the formula above.
o volume: Accepts no parameters and returns the double value for the volume
calculated using the using the formula above.
o toString: Returns a String containing the information about the
Trapezohedron object formatted as shown below, including decimal formatting
(“#,##0.0###”) for the double values. The newline (\n) and tab (\t) escape
sequences should be used to achieve the proper layout for the indented lines (use
\t rather than three spaces for the indentation). In addition to the field values (or
corresponding “get” methods), the following methods should be used to compute
appropriate values in the toString method: edgeLengthAntiprism(), longEdge(),
surfaceArea(), and volume(). Each line should have no trailing spaces (e.g., there
should be no spaces before a newline (\n) character). The toString value for
ex1, ex2, and ex3 respectively are shown below (the blank lines are not part of
the toString values).
Trapezohedron “Ex 1” is “red” with 20 edges and 12 vertices.
edge length antiprism = 8.0902 units
short edge = 5.0 units
long edge = 13.0902 units
surface area = 622.4746 square units
volume = 1,155.226 cubic units
Trapezohedron “Ex 2” is “blue” with 20 edges and 12 vertices.
edge length antiprism = 16.8276 units
short edge = 10.4 units
long edge = 27.2276 units
surface area = 2,693.074 square units
volume = 10,395.7774 cubic units
Trapezohedron “Ex 3” is “red, blue, tan” with 20 edges and 12 vertices.
edge length antiprism = 39.6418 units
short edge = 24.5 units
long edge = 64.1418 units
surface area = 14,945.6145 square units
volume = 135,911.1879 cubic units
Project: Trapezohedron App Page 4 of 5
Page 4 of 5
Code and Test: As you implement your Trapezohedron class, you should compile it and
then test it using interactions. For example, as soon you have implemented and
successfully compiled the constructor, you should create instances of Trapezohedron in
interactions (e.g., copy/paste the examples above on page 2). Remember that when you
have an instance on the workbench, you can unfold it to see its values. You can also
open a viewer canvas window and drag the instance from the Workbench tab to the
canvas window. After you have implemented and compiled one or more methods, create
an Trapezohedron object in interactions and invoke each of your methods on the object to
make sure the methods are working as intended. You may find it useful to create a
separate class with a main method that creates an instance of Trapezohedron then prints it
out. This would be similar to the TrapezohedronApp class you will create below, except
that in the TrapezohedronApp class you will read in the values and then create and print
the object.
• TrapezohedronApp.java
Requirements: Create an TrapezohedronApp class with a main method that reads in
values for label, color, and edge. After the values have been read in, main creates an
Trapezohedron object and then prints a new line and the object.
Design: The main method should prompt the user to enter the label, color, and short
edge. After a value is read in for the short edge, if the value is less than or equal to zero,
an appropriate message (see examples below) should be printed followed by a return
from main. Assuming that the short edge is positive, an Trapezohedron object should be
created and printed. Below is an example where the user has entered a negative value
for short edge followed by an example using the values from the first example above for
label, color, and edge. Your program input/output should be exactly as follows.
Example #0
Line # Program input/output
1
2
3
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5
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—-jGRASP exec: java TrapezohedronApp
Enter label, color, and short edge length for a trapezohedron.
label: Ex0
color: white
short edge: -9.8
Error: short edge must be greater than zero.
—-jGRASP: operation complete.
Example #1
Line # Program input/output
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—-jGRASP exec: java TrapezohedronApp
Enter label, color, and short edge length for a trapezohedron.
label: Ex1
color: red
short edge: 5.0
Trapezohedron “Ex1” is “red” with 20 edges and 12 vertices.
edge length antiprism = 8.0902 units
short edge = 5.0 units
long edge = 13.0902 units
surface area = 622.4746 square units
Project: Trapezohedron App Page 5 of 5
Page 5 of 5
11
12
volume = 1,155.226 cubic units
—-jGRASP: operation complete.
Code: Your program should use the nextLine method of the Scanner class to read user
input. Note that this method returns the input as a String, even when it appears to be
numeric value. Whenever necessary, you can use the Double.parseDouble method to
convert the input String to a double. For example, Double.parseDouble(s1) will
return the double value represented by String s1, assuming s1 represents a numeric value.
For the printed lines requesting input for label, color, and short edge, use a tab “\t” rather
than three spaces. After reading in the values, create the new Trapezohedron, say trap,
then print it: System.out.println(“\n” + trap);
Test: You should test several sets of data to make sure that your program is working
correctly. Although your main method may not use all the methods in Trapezohedron,
you should ensure that all your methods work according to the specification. You can
use interactions in jGRASP or you can write another class and main method to exercise
the methods. The viewer canvas should also be helpful, especially using the “Basic”
viewer and the “toString” viewer for an Trapezohedron object. Web-CAT will test all the
methods specified above for Trapezohedron to determine your project grade. You may
also find it useful to use the calculator at https://rechneronline.de/pi/trapezohedron.php.
When using the calculator, set the Trapezohedron field to 5- (pentagonal), set short edge
to a positive value, and then Round to 4 decimal places.
General Notes
1. All input from the keyboard and all output to the screen should done in the main method.
Only one Scanner object on System.in should be created and this should be done in the main
method. All printing (i.e., using the System.out.print and System.out.println methods) should
be in the main method. Hence, none of your methods in the Trapezohedron class should do
any input/output (I/O).
2. When a method has a return value, you can ignore the return value if it is no interest in the
current context. For example, when setShortEdge(3.5) is invoked, it returns true to let the
caller know the edge field was set; whereas setShortEdge(-3.5) will return false since the
edge field was not set. So, if the caller knows that x is positive, then the return value of
setShortEdge(x) can safely be ignored since it can be assumed to be true.
3. Even though your main method may not be using the return value of a method, you can
ensure that the return value is correct using interactions.
