HTW Berlin Fachbereich 4 Internationaler Bachelor Studiengang Internationale Medieninformatik (Bachelor) Info 2: Informatik II Summer Term 2023

Finger Exercises

Please have these completed before coming to the lab.

1. How do Julian Dates work? We discussed this in class. See if you can find more information on the Internet and put your sources in your report. Write out the abstract data type that you discussed during class.
   
   
2. Think up some good test cases for testing a JulianDate collection of classes. But what is a test case? A pair (input, expected output). That means, that you have to figure out before running the code what the program should output. Include some arithmetic methods such as daysBetween, tomorrow and yesterday.   

Lab exercises

These are the required exercises for this week. Work in groups of two, doing pair programming, and turn in the same report for each member of the pair. Remember to put your names on the report. You can continue to use BlueJ, or move to Eclipse or IntelliJ, if you wish.

You will be implementing an abstract data type. This means that you will make a class that represents the type you are implementing. If you have different ADTs specified, you have to decide what you need before you start. The class will have public methods with signatures matching those that you specified—or you need to explain why they had to be changed from what you specified. You may have any number of private methods. Of course, you will have to implement some sort of test harness to see if the implementation works.

1. Implement the abstract data type Julian Date you specified in the prelab as a class. If you are missing any methods, explain in your report how you figured out that they were missing, and how you implemented them. Construct a test harness—another class that tests your ADT class and tries to find errors in your implementation.
   
2. Now make a little program that uses your Julian Date class. The program should ask for a birthday and figure out how many days old the person is and what weekday they were born on. If today is their birthday, then write out a special message. If the person has lived a number of days that is divisible by 100, print a special message! Check your program using both of your birthdays. Which of you is the oldest? Is there a Sunday's Child?
3. Since you can calculate Sundays, can you write a little program to calculate in which years Christmas Eve is on a Sunday? 2017 was the last one, when is the next one?
4. A metric system is proposed to reform the calendar. It will have 10 regular days are a week, 10 weeks a month, 10 months a year. Extend your JulianDate class to a class MetricDate that has a method for converting from JulianDate to metric and from metric to JulianDate. How old are both of you on this metric system in years??

For the bored:

7. Can you calculate the date for Easter next year?
8. Make an app that uses the Julian Date and requests the user to input their birthday. If today is their birthday, then play some "Happy Birthday" song you find on the web. Who has the rights to this music, if you were going to use it online? Or is this in the public domain? You can display a cake with a candles animation on it, too...
   
9. Extend the JulianDate class to use a locale to determine the language and date style and then supply a readValidDate() method which will conduct a dialogue in the appropriate language as determined by the locale, and not return until a valid date has been entered. Implement at least two different languages.
10. (If you have a lot of time on your hands) Extend the JulianDate class to support a third locale, called ISO, which outputs the date in the format yyyy-mm-dd. This format is the ISO standard and is useful since sorting dates on this format will place them into ascending date order.
11. (If you have no social life outside of this class) Extend the JulianDate class with toString() methods that respect the locale and give proper month and weekday names in the appropriate languages.

For the really bored:

11. Genios is a service that indexes articles in very many German newspapers in magazines. It costs money to read the articles, but you can query the database and scrape the number of articles per day. Now, wouldn't it be fun to plot how many articles there are on a particular topic over a certain time period? Here's the result I got using Python to search for "plagiat*" and "doktor*" for every day, over a period of 10 years. Now guess what the funny peaks are. Python already has a built-in + operator for dates, so if you are using Python, please use your own nextDay function. The query string I used was
    "http://www.genios.de/dosearch?explicitSearch=true&q=" + keywordstr + "&dbShortcut=%3A2%3AALLEQUELLENNEU-1_%3A2%3AALLEQUELLENNEU&TI%2CUT%2CDZ=&NN%2C"+"AU%2CMM%2CZ2=&CO%2CC2%2CTA%2CKA%2CVA%2CZ1=&Z4=&Z5=&Z3=&timeFilterType=on&DT_from=" + self.startdate.strftime("%d.%m.%y") + "&DT_to=" + self.startdate.strftime("%d.%m.%y") + "&timeFilter=0&x=76&y=8"

Your report is due by 10.00 pm the night before your next lab! As in Informatics 1, We are more interested in process than in product, although we are now getting more interested in products as well. Your report should include any collaborators, summarize what you learned, and note the time you invested in this exercise. How many lines of code did you write for each exercise? Record this in your report.