Description
Overview: This project is the first of three parts that
will involve calculating the estimated monthly cost of
owning a bunny where the amount is based on the type
of bunny, its weight, and various additional costs. You
will develop Java classes that represent categories of
bunny: pet bunny, house bunny (a subclass of pet
bunny), jumping bunny, and show bunny. These
categories will be implemented as follows: an abstract
Bunny class which has three subclasses PetBunny,
JumpingBunny, and ShowBunny. The PetBunny class
has a subclass HouseBunny. The driver class for this
project, BunniesPart1.java, should contain a main
method that creates one or more instances of each of
the non-abstract classes in the Bunny hierarchy. As you develop each non-abstract class, you should
add code in the main method to create and print one or more instances of the class. Thus, after you
have created all the classes, your main method should create and print one or more objects (e.g., at
least one for each of the types PetBunny, HouseBunny , JumpingBunny, and ShowBunny. You can
use BunniesPart1 in conjunction with interactions by running the program in the canvas (or debugger
with a breakpoint) and single stepping until the each of the instances is created. You can then enter
interactions for the instances in the usual way. However, a more efficient way to test your methods
would be to create the JUnit test file (required for this project) for each class and write an appropriate
number of test methods to ensure the classes and methods meet the specifications. All of your files
should be in a single folder. You should create a jGRASP project upfront and then add the source
Project: Bunnies – Part 1 Page 2 of 10
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and test files as they are created. You should generate (or regenerate) the UML class diagram each
time you add a class to the project (see page 8).
You should read through the remainder of this assignment before you start coding.
• Bunny.java
Requirements: Create an abstract Bunny class that stores Bunny data and provides methods to
access the data. The Bunny class should implement the Comparable interface for Bunny
objects.
Design: The Bunny class has fields, a constructor, and methods as outlined below.
(1) Fields: Three instance variables for the Bunny’s name of type String, breed of type String,
and weight of type double. These variables should be declared with the protected access
modifier so that they are accessible in the subclasses of Bunny. The last field should be a
protected static variable, bunnyCount, of type int with protected access. This class variable is
used to track the number of bunnies that are created from the classes in the Bunny hierarchy.
These are the only fields that this class should have.
(2) Constructor: The Bunny class has a constructor that accepts three parameters representing
the values for the respective instance variables, assigns the values, and then increments the
bunnyCount class variable. Since this class is abstract, the constructor cannot be called with
the new operator to create an instance of Bunny. Instead, the constructor will be called from
the constructors of the subclasses of Bunny using super and the parameter list.
(3) Methods: Usually a class provides methods to access (or read) and modify each of its
instance variables (known as get and set methods) along with any other required methods. At
minimum you will need the following methods.
o getName: Accepts no parameters and returns a String representing the Bunny’s owner.
o setName: Accepts a String representing the name, sets the field, and returns nothing.
o getBreed: Accepts no parameters and returns a String representing the breed field.
o setBreed: Accepts a String representing the breed, sets the field, and returns nothing.
o getWeight: Accepts no parameters and returns a double representing the weight.
o setWeight: Accepts a double representing the weight, sets the field, and returns
nothing.
o getBunnyCount: Accepts no parameters and returns an int value of bunnyCount.
Since bunnyCount is static, this method should be static as well.
o resetBunnyCount: Accepts no parameters, resets bunnyCount to zero, and returns
nothing. Since bunnyCount is static, this method should be static as well.
o estimatedMonthlyCost: An abstract method that accepts no parameters and
returns a double representing the estimated monthly cost for the Bunny. Note that this
method has no body in Bunny; it will be overridden in its subclasses.
Project: Bunnies – Part 1 Page 3 of 10
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o toString: Returns a String describing the Bunny. This method will be inherited by
the subclasses although it may be overridden in the subclass as appropriate. If it is
overridden, then it should be called from the toString method in the subclasses of Bunny
using super.toString(). For an example of the toString result, see the PetBunny class
below. The first line and all or part of the second line in each result should be produced
by this toString method. Note that you can get the class name within the class by calling:
this.getClass().getName()
o equals: Accepts a parameter of type Object and returns false if the Object is a not a
Bunny; otherwise, when cast to a Bunny, if it has the same field values (ignoring case in
Strings) as the Bunny upon which the method was called, it returns true; otherwise, it
returns false. Note that this equals method with parameter type Object will be called by
the JUnit Assert.assertEquals method when two Bunny objects are checked for equality.
Below is a version you are free to use.
public boolean equals(Object obj) {
if (!(obj instanceof Bunny)) {
return false;
}
else {
Bunny b = (Bunny) obj;
return (name.equalsIgnoreCase(b.getName())
&& breed.equalsIgnoreCase(b.getBreed())
&& Math.abs(weight – b.getWeight()) < .000001); } } o hashCode(): Accepts no parameters and returns zero of type int. This method is required by Checkstyle if the equals method above is implemented. o compareTo: Takes a Bunny object as a parameter and returns an int indicating the results of comparing Bunny objects based on their respective names where the natural order is alphabetical (ignoring case). This method is required since the Bunny class implements the Comparable interface for Bunny. Code and Test: Since the Bunny class is abstract you cannot create instances of Bunny upon which to call the methods. However, these methods will be inherited by the subclasses of Bunny. You should consider first writing skeleton code for the methods in order to compile Bunny so that you can create the first subclass, PetBunny, described below. At this point you can begin completing the methods in Bunny and writing the JUnit test methods for your subclass test file (PetBunnyTest.java) that invoke/test the methods inherited from Bunny. • PetBunny.java Requirements: Derive the PetBunny class from the Bunny class. Design: The PetBunny class has fields, a constructor, and methods as outlined below. Project: Bunnies – Part 1 Page 4 of 10 Page 4 of 10 (1) Fields: One public constant of type double: BASE_COST = 1.85 (Note that a constant must be declared as both static and final.) This is the only field that should be declared in this class. (2) Constructor: The PetBunny class must contain a constructor that accepts three parameters representing the four instance fields in the Bunny class. Since this class is a subclass of Bunny, the super constructor should be called with field values for Bunny. Below are examples of how the constructor could be used to create a PetBunny object: PetBunny pb1 = new PetBunny(“Floppy”, “Holland Lop”, 3.5); (3) Methods: Usually a class provides methods to access (or read) and modify each of its instance variables (known as get and set methods) along with any other required methods. At minimum you will need the following methods. o estimatedMonthlyCost: Accepts no parameters and returns a double calculated as: BASE_COST * weight. o toString: None – this class will use the toString method from Bunny. Below is an example based on pb1 above. Note that Breed and Weight are each preceded by three spaces (not a tab). Floppy (PetBunny) Breed: Holland Lop Weight: 3.5 Estimated Monthly Cost: $6.48 Code and Test: As you implement the PetBunny class, you should compile and test it as methods are created. Although you could use interactions, it should be more efficient to test by creating appropriate JUnit test methods. You can now continue developing the methods in Bunny (parent class of PetBunny). The test methods in PetBunnyTest should be used to test the methods in both Bunny and PetBunny. Remember, a PetBunny is-a Bunny which means PetBunny inherited the instance methods defined in Bunny. Therefore, you can create instances of PetBunny in order to test methods of the Bunny class. You may also consider developing BunniesPart1 (page 7) in parallel with this class to aid in testing. • HouseBunny.java Requirements: Derive the HouseBunny class from the PetBunny class. Design: The HouseBunny class has fields, a constructor, and methods as outlined below. (1) Field: an instance variable for wearAndTear of type double, which should be declared with the private access modifier; one public constant of type double: BASE_COST = 2.25 These are the only fields that should be declared in this class. Constructor: The HouseBunny class must contain a constructor that accepts four parameters representing the three instance fields in the Bunny class (inherited by PetBunny) and one instance field from HouseBunny. Since this class is a subclass of PetBunny, the super constructor should be called with the values for the inherited fields. The instance variable for Project: Bunnies – Part 1 Page 5 of 10 Page 5 of 10 wearAndTear should be set with the last parameter of the HouseBunny constructor. Below is an example of how the constructor could be used to create a HouseBunny object. HouseBunny hb1 = new HouseBunny(“Spot”, “Really Mixed”, 5.8, 0.15); (2) Methods: Usually a class provides methods to access (or read) and modify each of its instance variables (known as get and set methods) along with any other required methods. At minimum you will need the following methods. o getWearAndTear: Accepts no parameters and returns a double representing the wearAndTear field. o setWearAndTear: Accepts a double representing the wearAndTear, sets the field, and returns nothing. o estimatedMonthlyCost: Accepts no parameters and returns a double calculated as: BASE_COST * weight * (1 + wearAndTear). o toString: The toString method required in the HouseBunny class should invoke the inherited toString method and then append wear and tear info to the result. Below is an example of the toString result for hb1 as declared above. Spot (HouseBunny) Breed: Really Mixed Weight: 5.8 Estimated Monthly Cost: $15.01 (includes 15.0% for wear and tear) Code and Test: As you implement the HouseBunny class, you should compile and test it as methods are created. Although you could use interactions, it should be more efficient to test by creating appropriate JUnit test methods. For example, as soon as you have implemented and successfully compiled the constructor, you should create an instance of HouseBunny in a JUnit test method in the HouseBunnyTest class and then run the test file. If you want to view your objects in the Canvas, set a breakpoint in your test method and then run Debug on the test file. When it stops at the breakpoint, step until the object is created. Then open a canvas window using the canvas button at the top of the Debug tab. After you drag the instance onto the canvas, you can examine it for correctness. If you change the viewer to “toString” view, you can see the formatted toString value. You can also enter the object variable name in interactions and press ENTER to see the toString value. Hint: If you use the same variable names for objects in the test methods, you can use the menu button on the viewer in the canvas to set “Scope Test” to “None”. This will allow you to use the same canvas with multiple test methods. You may also consider developing BunniesPart1 (page 7) in parallel with this class to aid in testing. • JumpingBunny.java Requirements: Derive the JumpingBunny class from the Bunny class. Design: The JumpingBunny class has fields, a constructor, and methods as outlined below. (1) Field: an instance variable for trainingCost of type double, which should be declared with the private access modifier; one public constant of type double: BASE_COST = 2.50. Project: Bunnies – Part 1 Page 6 of 10 Page 6 of 10 These are the only fields that should be declared in this class. (2) Constructor: The JumpingBunny class must contain a constructor that accepts four parameters representing the three instance fields in the Bunny class and one instance field from JumpingBunny. Since this class is a subclass of Bunny, the super constructor should be called with field values for Bunny. The instance variable for trainingCost should be set with the last parameter of the JumpingBunny constructor. Below is an example of how the constructor could be used to create a JumpingBunny object: JumpingBunny jb1 = new JumpingBunny(“Speedy”, “English”, 6.3, 25.0); (3) Methods: Usually a class provides methods to access (or read) and modify each of its instance variables (known as get and set methods) along with any other required methods. At minimum you will need the following method. o getTrainingCost: Accepts no parameters and returns a double representing the trainingCost field. o setTrainingCost: Accepts a double representing the trainingCost, sets the field, and returns nothing. o estimatedMonthlyCost: Accepts no parameters and returns a double calculated as: BASE_COST * weight + trainingCost. o toString: The toString method required in the JumpingBunny class should invoke the inherited toString method and then append training cost info to the result. Below is an example of the toString result for jb1 as declared above. Speedy (JumpingBunny) Breed: English Weight: 6.3 Estimated Monthly Cost: $40.75 (includes $25.00 for training) Code and Test: As you implement the JumpingBunny class, you should compile and test it as methods are created. Although you could use interactions, it should be more efficient to test by creating appropriate JUnit test methods in JumpingBunnyTest. You may also consider developing BunniesPart1 below in parallel with this class to aid in testing. For more details, see Code and Test above for the PetBunny and HouseBunny classes. • ShowBunny.java Requirements: Derive the ShowBunny class from the Bunny class. Design: The ShowBunny class has a field, a constructor, and methods as outlined below. (1) Field: an instance variable for groomingCost of type double, which should be declared with the private access modifier; one public constant of type double: BASE_COST = 2.75 These are the only fields that should be declared in this class. Project: Bunnies – Part 1 Page 7 of 10 Page 7 of 10 (2) Constructor: The ShowBunny class must contain a constructor that accepts four parameters representing the three instance fields in the Bunny class and one instance field from ShowBunny. Since this class is a subclass of Bunny, the super constructor should be called with field values for Bunny. The instance variable for groomingCost should be set with the last parameter of the ShowBunny constructor. Below is an example of how the constructor could be used to create a ShowBunny object. ShowBunny sb1 = new ShowBunny(“Bigun”, “Flemish Giant”, 14.6, 22.0); (3) Methods: Usually a class provides methods to access (or read) and modify each of its instance variables (known as get and set methods) along with any other required methods. At minimum you will need the following methods. o getGroomingCost: Accepts no parameters and returns a double representing the groomingCost. o setGroomingCost: Accepts a double representing the groomingCost, sets the field, and returns nothing. o estimatedMonthlyCost: Accepts no parameters and returns a double calculated as: BASE_COST * weight + groomingCost. o toString: The toString method required in the ShowBunny class should invoke the inherited toString method and then append grooming cost info to the result. Below is an example of the toString result for sb1 as declared above. Bigun (ShowBunny) Breed: Flemish Giant Weight: 14.6 Estimated Monthly Cost: $62.15 (includes $22.00 for grooming) Code and Test: As you implement the ShowBunny class, you should compile and test it as methods are created. Although you could use interactions, it should be more efficient to test by creating appropriate JUnit test methods in ShowBunnyTest. You may also consider developing BunniesPart1 below in parallel with this class to aid in testing. • BunniesPart1.java Requirements: Driver class with main method. Design: The BunniesPart1 class only has a main method as described below. The main method should be developed incrementally along with the classes above. For example, when you have compiled Bunny and PetBunny, you can add statements to main that create and print an instance of PetBunny. [Since Bunny is abstract you cannot create an instance of it.] When main is completed, it should contain statements that create and print one or more instances of PetBunny, HouseBunny, JumpingBunny, and ShowBunny. Since printing the objects does not show the actual fields, you should also run BunniesPart1 in the canvas (or debugger with a breakpoint) to examine the objects while the program is running. Between steps you can use interactions to invoke methods on the objects in the usual way. For example, if you create PetBunny pb1, as described above and your main method is stopped between steps after PetBunny pb1 has been created, you can enter the following in interactions to calculate the estimated monthly cost for the PetBunny object. Project: Bunnies – Part 1 Page 8 of 10 Page 8 of 10 M¼MMpb1.estimatedMonthlyCost() MMMM6.4750000000000005 Code and Test: After you have implemented the BunniesPart1 class, you should create the test file BunniesPart1Test.java in the usual way. The only test method you need is one that creates an instance of BunniesPart1 (to cover its default constructor), and then resets the class variable BunnyCount that was declared in Bunny and shared by each subclass. In the test method, you should declare and create an instance of BunniesPart1, reset BunnyCount, call your main method, then assert that BunnyCount is four (assuming that your main creates four objects from the Bunny hierarchy). The following statements accomplish the test. BunniesPart1 vp1 = new BunniesPart1(); Bunny.resetBunnyCount(); BunniesPart1.main(null); Assert.assertEquals(“Bunny.BunnyCount should be 8. “, 8, Bunny.getBunnyCount()); Project: Bunnies – Part 1 Page 9 of 10 Page 9 of 10 UML Class Diagram As you add your classes to the jGRASP project, you should generate the UML class diagram for the project. To layout the UML class diagram, right-click in the UML window and then click Layout > Tree Down. Click in the background to unselect the classes. You can then select the
BunniesPart1 class and move it around as appropriate. Below is an example. Note that the
dependencies represented by the red dashed arrows indicate that BunniesPart1 references each of
the subclasses of Bunny (i.e., the main method in BunniesPart1creates instances of each subclass
and prints then out).
UML Class Diagram for Bunnies Project
Project: Bunnies – Part 1 Page 10 of 10
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Canvas for BunniesPart1
Below is an example of a jGRASP viewer canvas for BunniesPart1 that contains two viewers for
each of the variables pb1, hb1, jb1, and sb1. The first viewer for each is set to Basic viewer and
the second is set to the toString viewer. A viewer for the class variable Bunny.BunnyCount is
near the bottom of the canvas. The canvas was created dragging instances from the debug tab
into a new canvas window and setting the appropriate viewer. Note that you will need to unfold
one of the instances in the debug tab to find the static variable BunnyCount. To display types
with the labels, click View on the canvas top menu bar then turn on Show RuntimeTypes in
Viewer Labels with the check box. Since you are printing the objects in main, you can see the
toString results in the Run I/O window. So a single canvas with all objects in the Basic viewer
may be more useful than the toString viewer.
