Make sure that the names of your methods match those listed above exactly, including capitalization. The number of parameters and their order must also match. The best way to ensure this is to copy and paste. Our testing will expect those method name and parameters, so any mismatch will fail during our testing. Parameter names will not be tested —you can change the parameter names if you want.

Each method must be preceded by an appropriate specification, as a Javadoc comment. The best way to ensure this is to copy and paste. After you have pasted, be sure to do any necessary editing. For example, the spec does not have to say that a function is static, because that is known from the header of the method. And the spec of a function does not have to say that the function yields a boolean or int or anything else, because that is known from the header of the method.

A precondition should not be tested by the method; it is the responsibility of the caller to ensure that the precondition is met. As an example, in method isMotherOf, the method body should not test whether fm is null. However, in function areSiblings, the tests for fm1 and fm2 not null MUST be made.

The number of children of a newly created rhino is 0. Whenever a rhino R is made the mother or father of another rhino, R's number of children should increase by 1.

It is possible for person R1 to be R2's mother, and visa versa, at the same time. We do not check for such strange occurrences.

Function toString
Here is an example of output from function toString:

"Male rhino Fatso. Tag 34. Born 6/2005. Has 2 children. Father Weighty. Mother unknown."

Here are some points about this output.

1. Exactly one blank separates each piece of information, and the periods are necessary.
2. "Male" or "Female" has to be capitalized.
3. If the mother field or father field is null, use "unknown" for its name; otherwise, use the name that appears in the mother or father.
4. In your method body, you may not use an if statement, but you can use a conditional expression —look it up in the index of the CD ProgramLive.

Your method bodies should have no if statements. Your method bodies should contain only assignments and return statements. Points will be deducted if if statements are used. Further, conditional expressions may be used only in function toString.

Class RhinoTester

How do you know whether class Rhino that you are designing is correct? The only way to be sure is to test it, to see if it does what it is supposed to do. It is not enough simply to try out your class Rhino in the interactions pane. Every time you write a method for your class Rhino, you should also write a couple of tests for it. Further, you should run your collection of tests frequently to make sure that everything works correctly.

Class RhinoTester will contain your JUnit test suite; it will perform these testing tasks for you. Make sure that your test suite adheres to the following principles:

• For each method in your class Rhino, your test suite should have at least one test case that tests that method.
• The more interesting or complex a method is, the more test cases you should have for it. What makes a method 'interesting' or complex can be the number of interesting combinations of inputs that method can have, the number of different results that the method can have when run several times, the different results that can arise when other methods are called before and after this method, and so on.
• Here is one important point. If an argument of a method can be null, there should be a test case that has that argument as null.
• Test very basic methods early in your test suite; then move on to more complex ones.
• Don't try to test too many things in a single test case. Each test case should test only a couple of conditions.

If a test changes static variables, they will retain their values in later tests. Also, the tests are not necessarily run in the order in which you list them in your test suite. So when testing static variables, record their initial value at the beginning of the test and test that the change in the value is what you expect.

How to do this assignment

• First, start a new folder on your harddrive that will contain the files for this project. Sart every new project in its own folder.
• Second, write a class Rhino using DrJava. In it, declare the fields in class Rhino, compiling often as you proceed. Write comments that specify what these fields mean.
• Third,
  • (1) Write the first constructor and all the getter methods of class Rhino.
  • (2) Put a method in class RhinoTester that tests whether the first constructor and all the getter methods work.
  • (3) Check that the first constructor and all the getter methods work as required. Don't go on to the next step until this is done.
• Fourth, for the second constructor, write it and test it as done for the first constructor.
• Fifth, write function toString and write a method in RhinoTester to test it thoroughly.
• Sixth, write each of the setter methods, add a method in Rhino to test them, and test them. We suggest writing and testing one method at a time —write a method, put tests for it in class RhinoTester, and test it thoroughly; then move on to the next.
• Seventh, add a method to RhinoTester to test the comparison methods. Then work on one of the comparison methods at a time: put in its header and specification (as a comment), write the method body, add test cases to the method in RhinoTester, and test and debug until the method works properly.

At each step, make sure all methods are correct before proceeding to the next step. When adding a new method, cut and paste the comment and the header from the assignment handout and then edit the comment.

Other hints and directions

• Do not use if statements when completing this assignment. For boolean expressions, the operators && (AND), || (OR), and ! (NOT) are sufficient to implement all the methods shown above. You will lose points for using if statements.
• Some of the Rhino methods can be implemented easily by using other Rhino methods that you have already created. Look for these cases. Take advantage of them as much as possible.
• Methods substring, toUpperCase, and toLowerCase in class String may be useful.
• Remember that a String literal is enclosed in double quotation marks and a char literal is enclosed in single quotation marks.
• Use method .equals to compare objects (including String objects) for equality and == to compare primitive values for equality.
• Only object variables can have the value null. So comparisons between primitive types and null are not legal.
• To create a JUnit test suite, select menu item File ->�New JUnit Test Case, and then replace the testX method with many methods that test your Rhino functionality.

Submitting the assignment

• Did you use an if statement? Get rid of it.
• Did you make sure that each method is tested enough? For example, if an argument can be null, is there at least one test case that has a call on the method with that argument being null?
• Did you check your javadoc? Click the javadoc button in the DrJava navigation bar. This will cause the specification of the classes and methods of the classes to be extracted from your program and html pages to be created that contain the specs. You should look at those specs carefully and make sure that the specs are suitable. Can you understand precisely what a method does based on the extracted spec? If not, fix the spec, generate the javadoc, and look at it again.

Submit only files that end with the .java. Be careful about this, because in the same place as your .java files you may also have files that end with .class or .java~. but otherwise have the same name.