CMSC 131 - Object-Oriented Programming I

Spring 2005

Archive of Old Announcements

Important announcements related to the course will be posted in the class CMSC 131 home page. Old announcements will be moved here.

Sun, May 15 (12:18 pm) Final Exam Review Session.   The review session will be on Monday May 16, from 8pm to 9pm in room CSI 1115. 

Sun, May 15 (9:21 am) HW8 scores and Quiz 8 scores are now available.  You have until Monday May 16 at 6pm, in order to submit a regrade request for hw8. We will not accept with any regrades requests or grade corrections after Monday.   

Wed, May 11 (9:58 am) Make sure that the grades recorded in are correct.  If you see any errors you must contact us ( by Friday May 13.  The only score we have not posted is the hw8 score.  We will not process any grade correction dealing with quizzes, exam1, exam2 or homeworks (one through seven), after this Friday.  The  only regrade requests we will process are those associated with hw8 which we hope to have ready by Saturday evening. Make sure you check your grades by Sunday morning as we expect to have all hw8 scores posted by then.   You will have until Monday May 16, at 6pm in order to submit a regrade request for hw8.  We will not deal with hw8 regrade requests after Monday. 

Wed, May 11 (9:58 am) Bonnie's office hours for this Friday May 13 are cancelled.

Wed, May 11 (9:58 am) Final Exam Review Session.   The review session will be on Monday May 16, from 8pm to 9pm in room CSI 1115. 

Wed, May 11 (9:10 am) Bonnie's office hours.   Her last office hours will be on Monday May 16 from 4pm to 5pm.

Wed, May 11 (9:10 am) Nelson's office hours.   Nelson will not have office hours this Friday May 13.  His last office hours will be on Monday May 16 from 10am to 11am.

Mon, May 9 (11:17 am) Quiz #7 has been graded.  You have until this Thursday May 12, to submit any regrade request.

Mon, May 9 (7:08 am) Homework #7 has been graded.  You have until this Thursday May 12, to submit any regrade request.

Sat, Apr 30 (7:08 am) We will give you points for course evaluations: There are two evaluations we would like you to complete:

1. Online evaluation: Visit the web page

and complete this course evaluation. Complete this evaluation by Friday May 6. Remember that we cannot look at these evaluations until after the course grades have been submitted, therefore be honest and tell us what you really think about the course (what is good, what is bad, what is terrible). This will help us make this course a better one.

2. In lab review: This will take place in lab on Wed May 11. You will complete a review we will provide. Notice it is an anonymous review were you don't need to write your name.

To encourage you to complete these reviews we will give you 20 pts if you complete both the online and in lab review. Notice that although we can not see the online reviews you complete we can receive a list of those that filled it out. Using this list we will give 10 pts to each of you. The other 10 pts will be for the in lab review. The TA will keep a list of those attending this lab review session and points will be granted accordingly.  This 20 pts represent Quiz #8.

Fri, May 6 (9:18 am) Extra office hours for Today Friday May 7

                    Dov -->11:00 am -12:30 pm, Nick --> 12:30 pm-2:00 pm

Wed, May 4 (7:09 pm) Message from Nelson to all cmsc131 lectures.  Over the summer I will be teaching cmsc131.  At the moment the enrollment for this class is low.  If you know of someone that wants to take cmsc131 please let them know this course is being offered over the summer.  Also, ask them to register as soon as possible.  Thank you for your help.

Wed, May 4 (7:00 pm)THERE IS NO LATE SUBMISSION DATE FOR QUIZ #7!! So you MUST submit this by Friday, May 6, 6:00pm.

Wed, May 4 (6:58 pm) There will be extra TA office hours this Friday between 11am and 2pm (for assistance with HW 8). Stay tuned for an announcement about who will provide these (and where).

Sat, Apr 30 (7:08 am) Quiz #7 The quiz should take a couple of hours to complete. Don't wait to start working on it. There are only a limited number of school labs where you can complete this exercise.

Sat, Apr 30 (7:08 am)  HW8 is a long homework. Please don't wait until the last minute to start working on it. Keep in mind that we don't have office hours over the weekend, and help through the wiki is limited.

Fri, Apr 29 (8:12 am) Public, Release and Secret tests are now available in HW6 Tests.

Thu, Apr 28 (8:12 am) Homework #6 grades have been posted.  You have until next Thursday to submit any regrade requests.  We will post the release and secret tests tomorrow.

Wed, Apr 27 (6:44 pm) Takehome Quiz #7 has been posted under "Quizzes".

Wed, Apr 27 (3:07 pm)  Homework #8 has been posted.

Wed, Apr 27 (3:07 pm)  Soccer class: Friday April, 29 final soccer class. We'll meet at 4 pm in front of the CSIC building and have some fun together! For more info email Massimo:"

Thu, Apr 22 (5:00 am)  There will not be a worksheet for Quiz#7.  The quiz will be a take-home exercise.  We will provide more information next Wednesday.

Thu, Apr 21 (1:10 am)  Bonnie Dorr's office hours are cancelled on Friday, April 22.

Wed, Apr 20 (8:30 am)  Thursday April 28th @ 7PM -- Join UMLUG as we discuss shell scripting in Linux. We'll have experts on hand that will talk about everything from bash to zsh. Free pizza and soda. Meeting will be in CSIC 1121.

Mon, Apr 18 (8:45 am) A special phone number: 202-452-7468. This is really funny.  I hope you enjoy it.  Nelson

Fri, Apr 15 (12:36 am) Bonnie Dorr's office hours are cancelled on Fri this week. If you need to meet with her, please send an email to set up an appointment for next week (or go to Monday's office hours). If a meeting is not necessary, but you have a question about the homework, please continue to use the usual mechanism (wiki, TA's, etc.)

Mon, Apr 11 (10:00 pm) HW#7 has been posted.

Mon, Apr 11 (2:00pm)Office hours for Bonnie on Wed will be held by Ryan in room AVW 1112. Important: Bonnie's office hours are again cancelled on Friday, April 15th. However, if you want an appointment, please contact her by email to set up a time to meet. (This worked well last week for those who sought this option.) If a meeting is not necessary, but you have a question about the homework, please continue to use the usual mechanism (wiki, TA's, etc.)

Mon, Apr 11 (8:48 am) Regarding HW#6.  You can add only a default constructor to the CompanyDatabase class.

Mon, Apr 7 (11:48 am) HW#5 grades are now available through  You have until next Thursday (April 14) to submit any regrade request.

Tue, Apr 5 (10:00 am) As mentioned in class yesterday, Bonnie Dorr's office hours are cancelled on Wed & Fri this week. If you need to speak with her, please send an email to set up an appointment. (Late Thursday afternoon may be an option for replacement of office hours, by appointment only.)

Mon, Apr 4 (8:30 am) HW#4 grades are now available through  You have until next Monday (April 11) to submit any regrade request.

Thu, Mar 31 (5:45pm)Friday's lecture will cover additional notes on JUnit Tests that have now been posted under the Lectures link.

Thu, Mar 31 (2:15pm)Quiz #6 will be on Wed, April 6th. The worksheet for this quiz is now posted at the Quizzes link.

Thu, Mar 31 (1:15pm)The grading of HW #4 and HW #5 will be complete by next week.

Wed, Mar 30 (7:50 pm): HW#6 requires javadoc documentation.  This is a topic we will discuss in lecture soon. This kind of documentation is simple and something you can add once you have finished the implementation of the homework code. 

Wed, Mar 30 (7:50 pm): If you decide to implement the Challenge Problem for HW#6, make sure the class defines a default constructor.

Wed, Mar 30 (6:50 pm): HW#6 has been posted.

Wed, Mar 30 (7:27 am): HW#6 will be posted later in the day (in the afternoon/evening).

Wed, Mar 30 (7:28 am): The UMD Paintball club is having an outing this coming Saturday, April 2nd and later in the month, April 30th. It will be $20 per person and an additional $30 if you need to rent equipment. Please contact Seth Clute at if interested. You can also check out

Tues, Mar 15 (12:33 pm): The University Senate elections are ending tommorow(03/16) at 5pm. If someone wants to vote, all they have to do is visit Testudo and use their directory ID and password (

Tues, Mar 15 (12:33 pm): A correction was made to the list of topics for Exam 2.  Make sure you have the new list.

Tues, Mar 15 (10:55am): Exam 2 information is now posted under the Exams link.

Mon, Mar 14 (8:29 am): We are updating the submit server software therefore the test reports are not accurate yet. If you are experiencing some problems with the server it may be due to this update.  We hope to have this situation resolved soon.  Notice that you can submit your project as usual (that component of the system is working as expected)

Sun, Mar 13 (8:00pm): Bonnie Dorr's office hours are cancelled on Friday, Mar 18. If you need to contact her, you must do so by Wednesday, Mar 16. She will not be available from that day on, until after spring break.

Sat, Mar 12 (11:47am): Power Outage NEXT WEEKEND. Computers used for this course (submit server and CVS repository) will be unavailable from 10:00 pm on Friday, March 18 through 7:00 am on Saturday, March 19. This outage will only affect those students that need to submit a late HW#5. Keep this outage in mind and don't submit your projects during the time period specified above. After 8:00 am on Saturday March 19, you should be able to submit as usual. We want to clarify that no extensions will be granted as a result of this outage.

Sat, Mar 12 (10:44 am):  The last set of office hours before Spring Break will be on Friday March 18.  The last time we will check the wiki will be on Friday.  There will be no office hours or wiki monitoring during Spring Break.

Sat, Mar 12 (10:44 am): Grades.  There was some HW#3 grades that were missing or incorrect.   We have fixed this situation.  Check your grades again and  if you see any problems talk to your teaching TA in lab on Monday (March 14).

Fri, Mar 11 (6:14 pm): Homework #5 has been posted. You can check out the homework files and submit as usual.  You may not see submit server tests results yet, but we will have the server running by Monday.  Remember that the public tests in the submit server have been included in the code distribution JUnit module. 

Fri, Mar 11 (10:23 pm): Homework #3 has been graded.  The grades are available through  Before you e-mail us regarding any grading questions make sure you read the instructions we have posted in the link Grades. You have until Wed Mar 16 to deal with any problems (e.g., regrades, clarifications, errors in grade recorded, etc.) related to the grading of HW#3.  No requests will be accepted afterwards.

Thur, March 10 (midnight) Additional lecture notes and snippets for Friday have now been posted under the "Lectures" link.

Thur March 10 (2:10 pm) On Monday or Wednesday of next week we will provide a lab worksheet with exercises that could help you prepare for midterm#2. Make an effort to attend these labs as these worksheets will not be available online. This is something new we are trying in labs.

Thur March 10 (1:00 pm) The HW#4 Challenge problem must be able to handle names that have as extensions Jr.,Sr.,I, II, III. Your program should be able to compare two names that have both middle initials and extensions. Remember that your Challenge program should be implemented in the class Challenge (basically copy the Name class to Challenge and modify the class to satisfy the challenge problem(s) you have chosen to implement).

Wed March 9 (midnight) Glue Account: Make sure you get a glue account this week. You will need this for a future quiz. Make sure your account works by logging into Remember, if you have a wam account that does not imply you have a glue account. More information about how to get glue accounts can be found in the Eclipse tutorial (see link to left of this page).

Wed March 9 (midnight) Early Warning Grades: We have submitted early warning grades and you should be able to see your grade through If you have any concerns about your grade, please see us during office hours (no e-mails, please).

Wed March 9 (midnight) Correction on grades: Please make sure that your grades in are correct. If there is any mistake (or any grade is missing) see your Teaching TA in lab next week and he/she will fix the problem for you. You have until next Monday (March 14) to report any grade mistakes. We will not accept any claims after that day.

Tue Mar 9 (9:57 pm) is back online.

Mon Mar 8 (9:37 pm) Modification to HW#4. If you are implementing the Challenge problem, then implement it in a class named Challenge. Please provide a main in the Challenge class that shows the Challenge problem version (1,2 or 3 gold stars) your class handles.

Mon Mar 7 (11:20 pm)In HW #4, you should be able to perform the relevant string processing by using the String.charAt method and looping (as shown in the chapt08 supplements). If you are feeling adventurous, you may use the String.trim and/or String.substring methods. (If you decide to do this, you are responsible for looking these up in the online Java API and/or reading about them in Appendix M of the book.)

Mon Mar 7 (12:12 am) The lecture notes and snippets for Week 7 are now posted under the "Lectures" link.

Sat Mar 5 (7:15 pm) Arrays should not be used in HW4. The online schedule has been updated to make this clearer.

Sat Mar 5 (11:21 am) Soccer group Massimo Renke (131 student) is organizing a group to play soccer. Those interested please get in touch with him. His e-mail is: If you want to play a particular sport or have a hobby you would like others to take part of, less us know and we will make an announcement.  You know, we do other things besides Java Programming :)

Tue Mar 1 (9:39pm): Homework #4 posted.

Mon, Feb 28 (11:50pm): A worksheet for Quiz #5 (next Wednesday) has now been posted.

Mon, Feb 28 (8:15am): Because of snow, there is no school today, which means the Review Session below is CANCELLED. See you at Wednesday's exam.

Sun, Feb 27 (10:40pm): UNLESS THERE IS SNOW, there is a Review Session for the exam on Monday, Feb 28, 8-9:30pm, in room 2117 CSI (the regular lecture room).

Fri, Feb 25 (2:31 pm) If you submit your homework #3 after 6pm on Fri, Feb 25 (today), you may get a message that indicates your project is late.  Ignore that message if you know the time at which you are submitting is considered an ontime submission.  The submit server still thinks the deadline is Friday Feb 25 at 6pm.  The person in charge of the server is not available to update this time, however, you will be able to submit with no problems and you will not be penalized if you submit your project before Saturday Feb 26 at 6pm.  Of course, if you submit after 6pm on Feb 26 you will receive a late penalty.

Fri, Feb 25 (8:13 am) Homework #3 is now due tomorrow Saturday Feb  26 at 6pm.  The one-day late submission is due on Sunday.  There will be no office hours on Saturday or Sunday.   The midterm will be on Wednesday as originally scheduled.

Thu, Feb 24 (6:13 pm) The Intro to Linux meeting (see Feb 21 below) has been moved to next Tuesday 3/1 at 5pm in 1121 CSIC.

Thu, Feb 24 (11:40 am): As announced below (see Wed Feb 23), the midterm exam will be in room CSI 1115 from 12-12:50 and 1-1:50. Morning lab sections (8am-12pm) are cancelled and Bonnie's 3-4pm lecture is cancelled. The students in sections 0101, 0201, 0202 should attend the 12pm exam; those in sections 0102, 0301, 0302 should attend the 1pm exam.

Thu, Feb 24 (8:27 am):  The web site is being updated and you will not be able to access your grades scores for a while.  We will post a note once the system is back online.

Wed, Feb 23 (11:30 am): The midterm exam will be in room CSI 1115 from 12-12:50 and 1-1:50. If you are in Nelson's class, you should attend the exam that corresponds to your own class time. If you are in Bonnie's class, you should attend the exam that corresponds to your lab section time.

Tues, Feb 22 (11:00 pm): I posted revised lecture supplements for tomorrow's lecture under the "Lectures" link. Also, you may have noticed that I have been storing the snippets there as "jar" files. You need to unpack these in the way described in the Eclipse tutorial here. Go down to "Importing Files" and look for (jar) File Import. You need to download the file as a .jar file first, and then import it inside of Eclipse.

Mon, Feb 21 (6:16 pm): The UM Linux Users Group will be holding an "Introduction to Linux" talk this Thursday Feb 24 at 8pm.   This is a great opportunity and we hope you can attend. More information about the talk is at the end of this page.  By the way, there will be FREE PIZZA!!!!!

Mon, Feb 21(11:25 am): Problems with the submission system have been fixed. 

Mon, Feb 21(11:23 am): The first midterm will be on Wednesday March 2, 2005.  We will let you know soon the location and time for your exam.  For information regarding the exam check the Exams link.

Mon, Feb 21(9:51 am): There are some problems with using the submit project option.  We are working on fixing this problem.

Linux Talk Information

Come learn about the FREE alternative to Windows called Linux which is sweeping the world.  We'll cover the basics of Linux and Open Source Software and go over what you need to consider when switching to Linux.

When: Thursday, February 24th, 8:00pm
Where: Computer Science Instructional Center (CSIC), Room 1121

Brought to you by the UM Linux Users Group

Fri, Feb 18 (8:40 pm): Midterm exam information has now been posted on the "Exams" link.

Fri, Feb 18 (6:50 pm): There was a 10 point error in grading a large number homework #1 submissions. We have now fixed this error and uploaded the changes. Please re-check your grade. If you have already submitted a regrade request and would like to withdraw it, please submit a regrade request that says: "Please disregard my previous regrade request."

Fri, Feb 18 (8:45 am): Homework #3 posted.

Fri, Feb 18 (8:46 am): Worksheet #4 posted.  Quiz #4 will be next Wednesday, Feb 23.

Thu, Feb 17 (5:00 pm): Please download the supplement for Chapt07 again. It has been modified significantly starting from where we left off on Wednesday ("Visibility and Encapsulation"). Also, the Chapt07.jar file has changed, so please download the new version. Regarding Chapt08, I will post the new version of the notes on Monday, so you should delete the previous version.

Thu, Feb 17 (2:00 pm): You have until Thursday Feb 24 to deal with any problems (e.g., regrades, clarifications, errors in grade recorded, etc.) related to the grading of HW#1.  No requests will be accepted afterwards.

Thu, Feb 17 (2:00 pm): Homework #1 has been graded.  The grades are available through  Before you e-mail us regarding any grading questions make sure you read the instructions we have posted in the link Grades

Wed, Feb 16 (4:45 pm): [Ignore this if you are not familiar with the concept of private vs. public visibility!] Some people in my (Bonnie's) class conjectured that the following line of code (in the Snippet that I posted) would result in a compile-time error:

if (( year == d.year) && (month == d.month) ...

The hypothesis was that, for example, d.year would not work because this is a reference to a private instance variable. As it turns out, this code does work (try it in Eclipse!) because this form of "association" is allowed for two objects of the same class. In fact, most "equals" methods would be defined in such a way that private instance variables are accessed.

Bottom line: Even though "year" and "month" and "day" are private, we are allowed to access them because we are inside the "blueprint" (the class definition itself). We cannot, however, access these variables outside of that blueprint.

Wed, Feb 16 (9:52 am): For Nelson's sections only.  This Friday Feb 18, our lectures will be in CSI 1115 (the original room we had).  This is only for this Friday.  We will be back to our regular room next Monday.

Tue, Feb 15 (8:41 am): GLUE ACCOUNT.  A glue account is required to access Eclipse in AVW 1442.  A glue account is different from a wam account and as a UMD student you are entitled to such account (it is free).  Please get one at the same office where you got your wam account.  Here is a link that may help:

Every student in the class should get one.  At some point or another you may need to access Eclipse at school and having this account will make this possible.

Tue, Feb 15 (8:41 am): SUBMISSION OF HW#2 Everyone should try to submit their HW#2 before the deadline even if you have not started working on the homework.  We want to make sure the submission process is working.  We have checked the number of people that have submitted and more than half of the class has not submitted yet.

Mon, Feb 14 (1:20 pm): Please note that the chapters posted in the lecture supplements do not correspond to the chapters in the book. I promise I will call them "topics", not "chapters", next time. :-) [BJD]

Mon, Feb 14 (9:30 am): Correction to HW#2.  In the sample run, when selecting color components,  the descriptions provides an incorrect color selection.  The color selection is "Yes" for red, "No" for green, "Yes" for blue (originally we had "Yes", "Yes" and "No".  The error has been corrected.  Notice that none of the images in the Sample Run changed.

Fri, Feb 11 (8:22 am): Quiz #3 will be on Wednesday Feb 16. The worksheet for this quiz (worksheet #3) is already posted.

Fri, Feb 11 (8:21 am): Homework #2 posted.

Thu, Feb 10 (10:05 pm): Message from Bonnie to all cmsc131 sections.  Tomorrow (Friday), my 4-5pm office hours will be run by Nikolaos Frangiadakis in room AVW 1112.

Tue, Feb 8 (6:27 pm): Message from Nelson to all cmsc131 sections.  Over the summer I will be teaching a program for high school students, to encourage them to the field of computer science.  The web page for the program is

It you can spread the word about this program I will appreciate it a lot.  In particular, if you can send this information to your high schools that will help me a lot.  Thanks,  Nelson

Fri, Feb 4 (8:46 am): Link to firefox has been corrected.

Fri, Feb 4 (8:46 am): A wiki link is now available for Homework #1.

Fri, Feb 4 (8:33 am): Homework #1 has been posted.

Thu, Feb 3 (6:05 pm): Tomorrow (Friday) we will start "Chapt 5" (Program Design and Development). The lecture supplements are now available under Week 3.

Thu, Feb 3 (5:05 pm): If you have not installed Eclipse/Java yet try the mirror site available through the Labs link.  It could save you a lot of time.

Thu, Feb 3 (3:05 pm): The submit server is a software we will use for your projects.  The server is incompatible with  Internet Explorer due to a bug in Explorer.  To use the server you must have another browser called firefox.  It is free and it is easy to install.  The firefox browser can be dowloaded from:


Please install this browser as soon as possible.  Notice that you don't have to uninstall Explorer.  You can have both browsers in your computer. 

If you have a Mac you should be fine with Safari.  Thank you for your cooperatbion in this matter.

Thu, Feb 3 (11:45 am):  The Labs link in the web page is now active. 

Thu, Feb 3 (8:34 am): The solution for Problem #7 in worksheet #2 had an error.  We have updated the worksheet with the correct solution.

Wed, Feb 2: Lecture room change for Nelson's section only.  Nelson's lectures (NOT THE LABS) will take place in CSI 2117 starting on Friday Feb 4.  This will be our new room.

Wed, Feb 2: Quiz #2.  Your second quiz will be on Wednesday, Feb 9. The worksheet (Worksheet #2) for this quiz can be found in the Quizzes link of the class web page.  Information about the quiz duration, coverage, etc., can be found on the worksheet.

Wed, Feb 2:  It is important that you can log onto to get your class account. Also you must have your Eclipse installation ready by Friday otherwise you will not be able to work on the project. If you are experiencing problems with any of the above items please see us immediately during office hours. We will not provide any project deadline extensions due to Eclipse installation problems.

Wed, Feb 2:  If you are a DSS student please contact us as soon as possible.  If you don't know what a DSS student is then ignore this message.

Sun, Jan 30: Changing your password.  To change your password on your "special account", you can log onto and run kpasswd.

Thu, Jan 27: Quiz #1.  Your first quiz will be on Wednesday, Feb 2. The worksheet (Worksheet #1) for this quiz can be found in the Quizzes link of the class web page.  Information about the quiz duration, coverage, etc., can be found on the worksheet.

Wed, Jan 26: IMPORTANT: Problems downloading Java  Many of you may have realized the java web site is experiencing problems.  We have notified the java distribution center.  Please try to install the software later in the evening or tomorrow.  We are waiting for them to take care of this problem.  Sorry if this causes any inconvenience.

Wed, Jan 19: Discussion sections cancelled this week  Discussion sessions will be cancelled on Wed, Jan 26. The lectures will still take place. The first discussion session will be meeting Mon, Jan 31.