HW3: People Sorter

To build a non-trivial program with Java, and to work with the List ADT.

The code that you write for this assignment will build on top of the List ADT and implementation that we saw in class on Friday. The three files you will need are:

• List.java
• MysteryListImplementation.class
• MysteryListImplementation$MysteryListIterator.class

Every source-code file you turn in must have your name in a comment at the top.

This is optionally a partner assignment. If you'd like to work in a pair, please figure out who you'd like to work with via Piazza or email, and then email me once your pair is decided. Make sure to put both people's names at the top of each file. Write your code by pair-programming: code together, at the same computer, and switch off who's at the keyboard. Only one of you should ultimately submit your team's code via Moodle.

It may be useful to refer to the code from Friday's class, particularly for the initialization of a List. The appendices of our book may also be useful. There is also a custom search box on the front page of our syllabus for searching the official Java API documentation (which, obnoxiously, doesn't have a search feature built in).

For this assignment, you will write a program that reads from a text file representing a sequence of people. Your program will need to represent each person as an instance of a class Person. It will need to convert the text file data into a List<Person>, sort the list, and print the list out in alphabetical order. This will give you practice working with the List ADT, String, File, Scanner, loops, and simple classes.

Note that it is a requirement of this assignment that you use the List ADT and implementation that I provided above.

The input file format

family-name,given-name,year-of-birth,month-of-birth,day-of-birth

Rowling,J.K.,1965,7,31
Bunny,Bugs,1940,7,27
Obama,Barack,1961,8,4
Gaga,Lady,1986,3,28
X,Malcolm,1925,5,19
Bush,George,1946,7,6
Merkel,Angela,1954,7,17
Bush,Vannevar,1890,3,11
Bush,George,1924,6,12
Madonna,,1958,8,16

The command-line syntax

java PeopleSorter people.txt

java PeopleSorter data/morepeople.txt

The expected output

given-name family-name age

Bugs Bunny 73
George Bush 89
George Bush 67
Vannevar Bush 123
Lady Gaga 27
Madonna 55
Barack Obama 52
J.K. Rowling 48
Malcolm X 88

Keep modularity in mind as you design your code, providing methods to encapsulate the main services you want from your Person objects. For example, you might organize your Person class like so:

public class Person {
    private String givenName;
    private String familyName;
    private int yearOfBirth;
    ...

    public Person(String gName, String fName, int year, int month, int day) {
       // Initialize the instance variables here.
       ...
    }

    public int age() {
       ...
    }

    public String getFullName() {
       ...
    }

    ...
}

A static-method-only approach to PeopleSorter might look like the following. The point here is to put major self-contained operations into separate methods. This way, the main method reads like a high-level outline of the process you're implementing.

public class PeopleSorter {
    public static void main(String[] args) {
        // If there's no command-line argument, print a usage statement 
        // and exit. Otherwise, use args[0] as the input file path.
        if (args.length == 0) {
           // ...
        }

        // Call loadPersonList to build a List of Person objects 
        // from the input file.
        String filePath = args[0];
        List<Person> personList = loadPersonList(filePath);

        // Call sortPersonList

        // Call printPersonList
    }

    public static List<Person> loadPersonList(String personFilePath) {
        // Use File and Scanner to set up a Scanner for the input file

        // Iterate through the file, instantiating new Person objects and adding
        // them to personList.
    }

    public static void sortPersonList(??) {
        // ...
    }

    public static void printPersonList(??) {
        // ...
    }
}

There's also a more object-oriented approach to the sorting half of things: you could make PeopleSorter into a real class that carries its own state (as opposed to an otherwise empty class with a bunch of static methods in it). This has some advantages that we might discuss in class.

Your program will probably consist of at least the files Person.java, PeopleSorter.java, List.java, MysteryListImplementation.class, and MysteryListImplementation$MysteryListIterator.class, but you may write others. You have a lot of freedom to design your solution here. Please make sure that every file you submit has your name (and your partner's name, if you're working in a pair) at the top.

Submit all of the Java source files that you wrote that are necessary to make your program work. Do not submit any .class files for the classes that you write, and also do not submit List.java or either of the .class files that I provided.

To prepare to submit all your files, zip them up into hw3.zip. Double-check your zip file: copy it to somewhere else, unzip it, copy over the three files that I provided to you, and try to compile and run your code. Also, make sure there are no directories and no extraneous stuff please. When you're satisfied that your submission is ready, upload the zip file to Moodle.

Start early, ask lots of questions, and have fun!

Assignment requirements

This is a partial list of the things that we'll be looking for when evaluating your work.

• Correct command-line syntax and behavior
• File parsing
• Sorting
• Output computations and formatting
• A full-featured Person class to represent individual people
• Program compiles
• Program runs correctly on test input
• Code uses the provided List interface and accompanying “mystery” implementation
• Code uses the ADT implementation correctly: MysteryListImplementation appears only in the initialization of List variables, and then only on the right-hand side (just as in the example code from class on Friday).

Grading

• Assignment Requirements — 20 points
• Comments, Style, and Design — 5 points