Project 04 Solution

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):

    • Spherocylinder.java

    • SpherocylinderApp.java

Specifications

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


A spherocylinder (or capsule) is a 3-dimensional object made up of two hemispheres connected by a cylinder as shown below. The formulas are provided to assist you in computing return values for the respective Spherocylinder methods described in this project.

The variables are abbreviated as follows:

r is radius

a is cylinder height C is Circumference SA is Surface Area V is Volume







Source for figures and formulas: https://en.wikipedia.org/wiki/Capsule_(geometry)

    • Spherocylinder.java

Requirements: Create a Spherocylinder class that stores the label, radius, and cylinder height where both radius and cylinder height are non-negative. The Spherocylinder class also includes methods to set and get each of these fields, as well as methods to calculate the circumference, surface area, and volume of a Spherocylinder object, and a method to provide a String value that describes a Spherocylinder object.



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

    (1) Fields (instance variables): label of type String, radius of type double, and cylinder 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 Spherocylinder class, and these should be the only instance variables (fields) in the class.

    (2) Constructor: Your Spherocylinder class must contain a public constructor that accepts three parameters (see types of above) representing the label, radius, and cylinder 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 Spherocylinder 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.

Spherocylinder example1 = new Spherocylinder("Small Example", 0.5, 0.25);

Spherocylinder example2 = new Spherocylinder(" Medium Example ", 10.8, 10.1);

Spherocylinder example3 = new Spherocylinder("Large Example", 98.32, 99.0);

    (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 Spherocylinder, 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 getRadius: Accepts no parameters and returns a double representing the radius field.

o setRadius: Takes a double parameter and returns a boolean. If the double parameter is non-negative, then the parameter is set to the radius field and the method returns true. Otherwise, the method returns false and the radius field is not set.

o getCylinderHeight: Accepts no parameters and returns a double representing the cylinder height field.

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

o circumference: Accepts no parameters and returns the double value for the circumference of the Spherocylinder.



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    o surfaceArea: Accepts no parameters and returns the double value for the total surface area of the Spherocylinder. [Be sure to avoid integer division in your expression.]

    o volume: Accepts no parameters and returns the double value for the volume of the Spherocylinder.

    o toString: Returns a String containing the information about the Spherocylinder 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: circumference(), 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 example1, example2, and example3 respectively are shown below (the blank lines are not part of the toString values).

Spherocylinder "Small Example" with radius 0.5 and cylinder height 0.25 has:

circumference = 3.142 units
surface area = 3.927 square units

volume = 0.72 cubic units

Spherocylinder "Medium Example" with radius 10.8 and cylinder height 10.1 has:

circumference = 67.858 units
surface area = 2,151.111 square units

volume = 8,977.666 cubic units

Spherocylinder "Large Example" with radius 98.32 and cylinder height 99.0 has:

circumference = 617.763 units
surface area = 182,635.388 square units

volume = 6,987,754.655 cubic units

Code and Test: As you implement your Spherocylinder 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 Spherocylinder 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 Spherocylinder 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 Spherocylinder then prints it out. This would be similar to the SpherocylinderApp class you will below, except that in the SpherocylinderApp class you will read in the values and then create and print the object.

    • SpherocylinderApp.java

    o Requirements: Create a SpherocylinderApp class with a main method that reads in values for label, radius, and cylinder height. After the values have been read in, main creates a Spherocylinder object and then prints a new line and the object.

    o Design: The main method should prompt the user to enter the label, radius, and cylinder height. After a value is read in for radius, if the value is less than zero, an appropriate message (see examples below) should be printed followed by a return from main. After a value is read in for cylinder height, if the value is less than zero, an appropriate message

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(see examples below) should be printed followed by a return from main. Assuming that both radius and cylinder height are non-negative, a Spherocylinder object should be created and printed. Below are three examples: (1) the user has entered a negative value for radius, (2) the user has entered a negative value for cylinder height, and (3) the user has entered the values from the first example above for label, radius, and cylinder height. Your program input/output should be exactly as follows.


Line #    Program input/output


    1 Enter label, radius, and cylinder height for a spherocylinder.

    2 label: One with a bad radius
    3 radius: -10.6
    4 Error: radius must be non-negative.
5

Line #    Program input/output


    1 Enter label, radius, and cylinder height for a spherocylinder.

    2 label: One with a bad cylinder height
    3 radius: 12.5
    4 cylinder height: -3.5
    5 Error: cylinder height must be non-negative.


Line #    Program input/output


    1 Enter label, radius, and cylinder height for a spherocylinder.

    2 label: Small Example
    3 radius: 0.5
    4 cylinder height: 0.25
5
    6 Spherocylinder "Small Example" with radius 0.5 and cylinder height 0.25 has:
    7 circumference = 3.142 units
    8 surface area = 3.927 square units
    9 volume = 0.72 cubic units


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, radius, and cylinder height, use a tab "\t" rather than three spaces. The object can be printed simply by using its variable name; i.e., when the object variable name is evaluated in the print 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 Spherocylinder, 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 Spherocylinder object. Web-CAT will test all of the methods specified above for Spherocylinder to determine your project grade.



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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 Spherocylinder 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 setRadius(3.5) is invoked, it sets the radius field and returns true; whereas setRadius(-3.5)will return false without setting the radius field. If the caller knows that the value of x is non-negative in the method call setRadius(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 return value so the method to indicate whether or not the setRadius method did in fact set the field.

    3. If the caller knows that the value of x is non-negative in the method call setRadius(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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