Method	Description
getName()	= the name of this rhino (a String)
getGender()	= the gender of this rhino (a char).
getMOB()	= the month in which this rhino was born, in the range 1..12 (an int).
getYOB()	= the year in which this rhino was born (an int).
getFather()	= (the name of the object representing) the father of this rhino (a Rhino).
getMother()	= (the name of the object representing) the mother of this rhino (a Rhino).
getTag()	= this rhino's tag (–1 if none) (an int)
getNumberChildren	= the number of children of this Rhino.
toString()	= a String representation of this Rhino. It has to be in a precise format discussed below.

Method	Description
setName(String s)	Set the name of this rhino to s.
setGender(char g)	Set the gender of the rhino to g.
setMOB(int i)	Set the month of birth of this rhino to i.
setYOB(int i)	Set the year of birth of this rhino to i.
setTag(int t)	Set this rhino's tag to t. Precondition: t ≥ 0 and the tag is currently –1.
setFather(Rhino r)	Set this rhino's father to r. Precondition: This rhino's father is null, r is not null, and r is male.
setMother(Rhino r)	Set this rhino's mother to r. Precondition: This rhino's mother is null, r is not null, and r is female.

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 names, 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,or "spec", 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 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. For example, it is a mistake to call method setFather with null for the father argument.

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.

In writing methods setFather (and setMother), be careful! If F is becoming the father of this Rhino, then F has one more child, and its field that contains its number of children has to be updated accordingly.

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

"M rhino Fatso. Tag 34. Born 6/2005. Has 2 children."

Here are some points about this output.

1. Exactly one blank separates each piece of information, and the periods are necessary.
2. The 'M' at the beginning means it is a male. Use 'F' for a female.
3. The mother and father are not described in the output of this function.
4. The word "children" should always appear. do not change it to "child" if there is 1 children.

Class RhinoTester

How do you know whether your class Rhino 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.

Here is an example of a test method, with a test case for one getter method. Put all test cases for getter methods in one such test method.

/**Test first Rhino constructor and getter methods*/
public void testGetters() {
     Rhino r1= new Rhino("R1Fatso", 5, 2005, 'M');
     assertEquals("R1Fatso", r1.getName());
}

How to do this assignment

• First, start a new folder on your hard drive that will contain the files for this project. Start 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 constructor and all the getter methods of class Rhino.
  • (2) Check that the constructor and the getter methods work properly. Do this by writing something like this in the interactions pane:

    r= new Rhino("John", 1, 2007, 'M');

  and then write calls on all the getter methods in folder r to be sure that they produce what is expected.

• Fourth, write function toString and write a method in RhinoTester to test it thoroughly.
• Fifth, 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 method.

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.
• Remember that a String literal is enclosed in double quotation marks and a char literal is enclosed in single quotation marks.
• Your class RhinoTester will probably have three test methods in it: one for the constructor and getter methods, one for method toString, and a third for the setter methods.

Grading guide

10 points for suitable definitions of variables on the fields of class Rhino
15 points for suitable Javadoc specifications on methods in class Rhino
25 points for the constructor and getter methods in class Rhino and 10 points for testcases for them in class RhinoTester.
10 points for method toString in class Rhino and 5 points for suitable testcases for it in class RhinoTester.
15 points for the setter methods in class Rhino and 10 points for testcases for them in class RhinoTester.

Submitting the assignment

Check these points before you submit your assignment

• 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.