Project 4 Solution

Deliverables

Your project files should be submitted to Web-CAT by the due date and time specified. You may submit your files to the skeleton code assignment until the project due date but should try to do this much earlier. The skeleton code assignment is ungraded, but it checks that your classes and methods are named correctly and that methods and parameters are correctly typed. The files you submit to skeleton code assignment may be incomplete in the sense that method bodies have at least a return statement if applicable or they may be essentially completed files. In order to avoid a late penalty for the project, you must submit your completed code files to Web-CAT no later than 11:59 PM on the due date for the completed code. If you are unable to submit via Web-CAT, you should e-mail your files in a zip file to your TA before the deadline.

Files to submit to Web-CAT (both files must be submitted together):

    • ConicalFrustum.java

    • ConicalFrustumApp.java

Specifications

Overview: You will write a program this week that is composed of two classes: (1) ConicalFrustum, which defines ConicalFrustum objects, and (2) ConicalFrustumApp, which has a main method that reads in data, creates a ConicalFrustum object, and then prints the object.

A Conical Frustum is a Frustum created by slicing the top off a cone (with the cut made parallel to the base), forming a lower base and an upper base that are circular and parallel.


r1    radius of top


r2    radius of bottom
    h height

    s slant height

    S lateral surface area V volume

A  total surface area

V =
π ∗ h
(r*
+
+ r+
+
+ (r* ∗ r+))

3






s = /(r* − r+)+ + h+

S = π * (r1 + r2) * s
A = π * (r12 + r22 + (r1 + r2) * s)

Source for figures and formulas: https://www.calculatorsoup.com/images/frustum001.gif

    • ConicalFrustum.java

Requirements: Create a ConicalFrustum class that stores the label, radius of top, radius of bottom, and height where the radii and height are non-negative. The ConicalFrustum class also includes methods to set and get each of these fields, as well as methods to calculate the volume, slant height, lateral surface area, and total surface area of a ConicalFrustum object, and a method to provide a String value that describes a ConicalFrustum object.

Design:  The ConicalFrustum class has fields, a constructor, and methods as outlined below.

        (1) Fields (instance variables): label of type String, radius1 of type double, radius2 of type double, and height of type double. Initialize the String to "" and the double variables to 0 in their respective declarations. These instance variables should be private so that they are not directly accessible from outside of the ConicalFrustum class, and these should be the only instance variables (fields) in the class.

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Project: ConicalFrustum App

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    (2) Constructor: Your ConicalFrustum class must contain a public constructor that accepts four parameters (see types of above) representing the label, radius1, radius2, and height. Instead of assigning the parameters directly to the fields, the respective set method for each field (described below) should be called since they are checking the validity of the parameter. For example, instead of using the statement label = labelIn; use the statement setLabel(labelIn); Below are examples of how the constructor could be used to create ConicalFrustum 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.

ConicalFrustum example1 = new ConicalFrustum("Small", 0.5, 0.75, 0.25);

ConicalFrustum example2 = new ConicalFrustum(" Medium ", 5.1, 10.2, 15.9);

ConicalFrustum example3 = new ConicalFrustum("Large", 98.32, 199.0, 250.0);

    (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 ConicalFrustum, which should each be public, are described below. See the formulas in the figure above and the Code and Test section below for information on constructing these methods.

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 “trimmed” String is set to the label field and the method returns true. Otherwise, the method returns false and the label is not set.

o getRadius1: Accepts no parameters and returns a double representing the radius1 field.

o setRadius1: Takes a double parameter and returns a boolean. If the double parameter is non-negative, then the parameter is set to the radius1 field and the method returns true. Otherwise, the method returns false and the radius1 field is not set.
o getRadius2: Accepts no parameters and returns a double representing the radius2 field.

o setRadius2: Takes a double parameter and returns a boolean. If the double parameter is non-negative, then the parameter is set to the radius2 field and the method returns true. Otherwise, the method returns false and the radius2 field is not set.
o getHeight: Accepts no parameters and returns a double representing the height field.

o setHeight: Accepts a double parameter and returns a boolean as follows. If the double parameter is non-negative, then the parameter is set to the height field and the method returns true. Otherwise, the method returns false and the height field is not set.

o volume: Accepts no parameters and returns the double value for the volume of the ConicalFrustum. [Be sure to avoid integer division in your expression.]

o slantHeight: Accepts no parameters and returns the double value for the slant height of the ConicalFrustum.

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Project: ConicalFrustum App

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    o lateralSurfaceArea: Accepts no parameters and returns the double value for the lateral surface area of the ConicalFrustum. Be sure to call your slantHeight method as appropriate.

    o totalSurfaceArea: Accepts no parameters and returns the double value for the total surface area of the ConicalFrustum. Be sure to call your slantHeight method as appropriate.

    o toString: Returns a String containing the information about the ConicalFrustum object formatted as shown below, including decimal formatting ("#,##0.0##") for the double values. Newline and tab escape sequences should be used to achieve the proper layout. In addition to the field values (or corresponding “get” methods), the following methods should be used to compute appropriate values in the toString method: volume(), slantHeight(), lateralSurfaceArea(), and totallSurfaceArea(). Each line should have no trailing spaces (e.g., there should be no spaces before a newline (\n) character). The toString value for example1, example2, and example3 respectively are shown below (the blank lines are not part of the toString values).

ConicalFrustum "Small" with radius1 = 0.5, radius2 = 0.75, and height = 0.25 has:

volume = 0.311 cubic units

slant height = 0.354 units

lateral surface area = 1.388 units

total surface area = 3.941 square units

ConicalFrustum "Medium" with radius1 = 5.1, radius2 = 10.2, and height = 15.9 has:

volume = 3,031.546 cubic units
slant height = 16.698 units
lateral surface area = 802.608 units

total surface area = 1,211.172 square units

ConicalFrustum "Large" with radius1 = 98.32, radius2 = 199.0, and height = 250.0 has:

volume = 18,020,568.788 cubic units
slant height = 269.512 units
lateral surface area = 251,739.485 units total surface area = 406,518.914 square units

Code and Test: As you implement your ConicalFrustum 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 ConicalFrustum in interactions (e.g., copy/paste the examples 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 a ConicalFrustum 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 ConicalFrustum then prints it out. This would be similar to the ConicalFrustumApp class you will below, except that in the ConicalFrustumApp class you will read in the values and then create and print the object.








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Project: ConicalFrustum App

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    • ConicalFrustumApp.java

    o Requirements: Create a ConicalFrustumApp class with a main method that reads in values for label, radius1, radius2, and height. After the values have been read in, main creates a ConicalFrustum object and then prints the object.

    o Design: The main method should prompt the user to enter the label, radius1, radius2, and height. After each numeric value is read (i.e., radius1, radius2, and height), if the value is less than zero, an appropriate message (see examples below) should be printed followed by a return statement to end main. Consider having three separate if statements. Assuming that radius1, radius2, and height are non-negative, a ConicalFrustum object should be created and printed. Below are four examples: (1) the user has entered a negative value for radius1, (2) the user has entered a negative value for radius2, (3) the user has entered a negative value for height, and (4) the user has entered the values from the first example above for label, radius1, radius2, and height. Your program input/output should be exactly as follows.


Line #    Program input/output


    1 Enter label, radius1, radius2, and height for a conical frustum.

    2 label: One with a bad radius1
    3 radius1: -1
    4 Error: radius1 must be non-negative.



Line #    Program input/output


    1 Enter label, radius1, radius2, and height for a conical frustum.

    2 label: One with a bad radius2
    3 radius1: 10.5
    4 radius2: -2.5
    5 Error: radius2 must be non-negative.



Line #    Program input/output


    1 Enter label, radius1, radius2, and height for a conical frustum.

    2 label: One with a bad height
    3 radius1: 25
    4 radius2: 26
    5 height: -1
    6 Error: height must be non-negative.



Line #    Program input/output


    1 Enter label, radius1, radius2, and height for a conical frustum.

    2 label: Small
    3 radius1: 0.5
    4 radius2: 0.75
    5 height: 0.25
    6 ConicalFrustum "Small" with radius1 = 0.5, radius2 = 0.75, and height = 0.25 has:
    7 volume = 0.311 cubic units
    8 slant height = 0.354 units
    9 lateral surface area = 1.388 units
    10 total surface area = 3.941 square units






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Project: ConicalFrustum App

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Code: To read user input, your program should use the nextLine method of the Scanner class. Note that this method returns the input as a String. 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. For the printed lines requesting input for label, radius1, radius2, and height, use a tab "\t" rather than three spaces. After you have created the object, it can be printed simply by using its variable name; i.e., when the object variable name is evaluated in the println statement, its toString()method is automatically called. So printing the object reference variable myObj is equivalent to printing the return value of the myObj.toString() method call.

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 ConicalFrustum, you should ensure that all of 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 a ConicalFrustum object. Web-CAT will test all of the methods specified above for ConicalFrustum to determine your project grade.

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 ConicalFrustum 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 setRadius1(3.5) is invoked, it sets the radius1 field and returns true; whereas setRadius1(-3.5) will return false without setting the radius1 field. If the caller knows that the value of x is non-negative in the method call setRadius1(x), it can be assumed that the field was set appropriately and the return value can be safely ignored. Although caller can always ignore the return value; however, it is important to provide the boolean return value to indicate whether or not the setRadius1 method did in fact set the field.

    3. If the caller knows that the value of x is non-negative in the method call setRadius1(x), it can be assumed that the field was set appropriately and the return value can be ignored safely.

    4. Even though your main method may not be using the return type of a method, you can ensure that the return type is correct using interactions.




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