SC/CSE 1030 - Announcements

The Lab Test #2 Grade Reports have been e-mailed to your CSE accounts. The Computer Science Department Office has your Final Exams (I think that the office staff will let you see your exams if you ask nicely).

I know that you are probably interested in knowing how the marks went for the whole class. Here are some interesting facts:

The class average of the final grades was a C+, and the highest mark was 94%.

At the end of term, there were 104 registered students, 57 of whom achieved grades above the 65% cutoff and so will be able to enter the Computer Science or Digital Media streams next term. This is an unusually high number of students - Well Done!

You can see your grades by typing the following command into the lab (Prism) computers:

   courseInfo 1030 2012-13 F

Have a great Holiday. Good luck with your future studies!

Don't forget to bring ID.

Please come on time.

The Final Exam will primarily focus on the materials from the later half of the course, although there will be a few questions on material from the first half.

Tomorrow's lecture is our last lecture, and we will be doing a review for the final exam. Please bring your questions - let me know what areas of the course you would like reviewed.

I have had several requests from students to wish to rewrite the Lab Test, but it would not be fair to the rest of the class to let students rewrite the test.

Don't forget to bring ID.
Please come on time.
If you are registered in the Tuesday lab section (01) you must do the lab test on Tuesday.

Here are some practice questions to help you prepare for Lab Test #2, which will be held in the regularly scheduled lab times next week. Remember, please attend the lab section that you are officially enrolled in for the lab test next week.

Create a Java class that will allow you to count how many unique integers there are in a set. You can use either an Array or a Queue data structure to solve this problem. (You may not use the Java API Array or Queue classes.) Your implementation should include the following functions:

void uniqueCounter.add(int x)

This function adds an integer to the uniqueCounter class, so long as that integer is not already in this uniqueCounter class.

void uniqueCounter.remove(int x)

This function removes an integer from the uniqueCounter class if the integer was previously added to the class.

int uniqueCounter.getCount()

This function returns the number of unique integers in the uniqueCounter class.

Example usage:

uniqueCounter uc = new uniqueCounter();
uc.add(10);
uc.add(5);
uc.add(20);
uc.add(5);    // note that this duplicate is not counted
uc.add(15);
uc.add(10);   // neither is this one

At this point the uc.getCount() function would return 4. because 4 unique integers have been added to the uniqueCounter object - the duplicates are not counted.

Use a linked-list to create a priorityQueue class. As we have seen in class, linear searching through a set of objects takes O(n) time. A binary search is faster, it is O(log n) time, but you can't do a binary search on a linked-list. One way to speed-up the average access time of a linked list, is to keep the more frequently accessed objects near to the front of the list. A priority queue does exactly this. Whenever an object is retrieved from a priority queue it is moved from wherever it was, to the head of the list, so that it will be quicker to find next time.

So, for example, this code:

priorityQueue pq = new priorityQueue();
pq.add(10);
pq.add(5);
pq.add(20);
pq.add(15);

will produce a priority queue that internally looks like this:

head --> 15 --> 20 --> 5 --> 10

note that the nodes have been added to the head of the list, so they are in the reverse order from how they were added (we say that the nodes are in "most recently used order").

Next, after we run the code: pq.find(5), the priority queue will look like this:

head --> 5 --> 15 --> 20 --> 10

See how "5" was moved to the front of the list?

If we code pq.find(5) again, then the list will not be rearranged, but we will find "5" very quickly because it is at the head of the list.

Issuing: pq.find(10) will again rearrange the list:

head --> 10 --> 5 --> 15 --> 20

leaving the nodes generally in the same order that they were, but translocating node "10" to the head of the list.

Implement the priorityQueue class, having these two functions:

void priorityQueue.add(int x)

Adds a new node to the head of the priority queue.

boolean priorityQueue.find(int x)

Searches the priority queue for the node "x". If the node is found then the function returns true, but also the node "x" is moved to the front of the list Fr faster access next time.

Use recursion when you implement the priorityQueue.find() function. Do not use any of the Java API Collections classes.

Duplicate values are not allowed in a priority queue.

Use an array to implement a Stack data structure. We saw an example of a stack when we discussed the execution stack in the course module on recursion. A stack has three operations:

void stack.push(String x)

Adds the specified data to the top of the stack.

String stack.pop()

Removes the datum from the top of the stack and returns it.

boolean stack.isEmpty()

Returns a boolean value indicating whether or not the stack is empty.

so, after the following code has run:

stack s = new stack ();
s.push (10);

the stack looks like this:

s = 10

and after:

s.push (5);

the stack looks like this:

s = 5, 10

and after:

s.push (20);

we see:

s = 20, 5, 10

At this point, s.pop() would return "20", and leave the stack looking like this:

s = 5, 10

Duplicate values are allowed in a stack.

Again, don't use any of the Java Collections.

Some of the programs we will be discussing in the lecture are available for download (available as .java files and .pdf files):

Also, don't forget that Lab Test #2 is scheduled for next week during the regular lab times.

Also, the course evaluation questionnaires will be administered at the end of tomorrow's class.

Some of the programs we will be discussing in the lecture are available for download (available as .java files and .pdf files):

Also, don't forget that Lab Test #2 is scheduled for next week, during the regular lab times.

The Assignment #6 Grade Reports and Solutions have been e-mailed to your Prism accounts. Please double-check your grades by typing: courseInfo 1030.

Additionally, Steven tells me that there is still some confusion regarding static versus instance data. He has written the following demo program to illustrate the difference. I will discuss his program in class, but you should definitely download it, look at it, compile and run it, and see what happens if you take the 'static' keyword out of line 7. Counter.java

Also, please note that we will be missing 1 TA during the Tuesday lab session this week, because our TA Steven is being awarded the FSE Excellence in Teaching Award - Congratulations Steven! So for the Tuesday lab session this week there will be a TA in LAS1006, but LAS1002 will be unstaffed.

I have information regarding some important dates:

The registrar's office has released the final exam schedule. The CSE1030 Final (Written) Exam is scheduled for Thursday, December 6, 2012, at 14:00 in LAS C.

The last date to drop this course without receiving a grade is Friday of this week (November 9th).

• In class tomorrow we will finish the last module on the Graphical User Interface, so there are no new notes.

• Also, at the end of class tomorrow, the midterms will be returned and we will take-up the answers.

• Remember to check the York Weather Status Webpage for updates regarding Hurricane Sandy.

During the last lecture you said something about how the TA's will not use the tester program a5.java but a similar tester to mark our assignments. I dont know why but does this mean that the tester provided to us (a5.java) is not accurate in giving us the correct results to our tests? Should I trust the results i am given when using a5.java if it tells me i pass all the tests? Should i expect a 10/10 on the assignment?

The tester programs that I have been providing to you are intended to help you check your assignments, but the responsibility to test your code lies with you - you should be testing your own code. Also, I am under no obligation to provide any of the testing program to you - your Math profs don't provide the answer key for your homework to you do they?

I provide the tester programs to try to help you, but there are lots of things that the tester program simply cannot test, such as:

• Does your code have adequate comments?
• Does your code have "style"?
• Did you code your solution in a reasonable way? (Using appropriate data and code members, for example some students used Map<Integer,Musican> to store the list of Musicians - this is not how Maps are supposed to be used, the students should have used the much more efficient HashSet or LinkedList, although their code passed the tester program tests)
• Does your code do what the assignment asks, or are you just "faking-out" the tester by providing faked responses to it's queries?
• Did you plagiarise your friend's solution?
• etc.

So to answer this student's question: No. Just because you pass the tests in the tester program DOES NOT mean you are guarenteed a 10/10 on the assignment. The TAs and I have worked (and are working) very hard to try to make the marking fair and reasonable, and providing the tester program to you is a part of that. But we do have our own code that helps us with the marking. If you have an issue with the marking (a real, legitimate issue, not a whine about a 1/2 mark that you know you should have lost anyway) then please come and see me. My objective, at the end of the day, is to make you able to write "good code", not merely the bare minimum of code needed to get passed the tester program.

The programs to be demonstrated as part of the third GUI module are available for download:
DemoAbsolute.java
DemoBorderLayout.java
DemoBoxLayout.java
DemoFlowLayout.java
DemoGridLayout.java
DemoLayoutExample.java

Additionally, tomorrow we will be looking at the "Alien Attack" program in some detail, so I'm providing .PDF files of the source code (AlienAttack.pdf, GamePanel.pdf, and, Sprite.pdf), and the complete package (with code and graphics files) for your reference (AlienAttack.zip). Most operating systems will open a .zip file if you double-click on it. You can extract the files from the .zip file on the Prism computers by (1) saving the AlienAttack.zip file somewhere, and (2) typing: unzip AlienAttack.zip.

Don't forget to bring ID.
Please come on time.
If you are registered in the Tuesday lab section (01) you must do the lab test today.

A solution to practice lab test #2 also turned up, here is it: GraduateStudent.java.

Also, don't forget that this week we have the Midterm during Tuesday's class time, and Lab Test #1 during the labs - attend the lab section that you are registered in! To maximise the time you get to complete your tests, please come to class and the labs on time. And lastly, don't forget to bring your ID to the tests!

Also, don't forget that the Midterm and Lab Test #1 are both next week.

To check your grades for this course you should login to your Prism account and type the command courseInfo 1030. Please double-check your marks with the courseInfo command - although these marks are not final or official until the Department approves of them at the of term, courseInfo shows you what has been recorded in the marks database.

The TA told me that he found more plagiarism than on past assignments - please remember that you should only submit your own work for assignments, in accordance with the academic policy we discussed in class, and that appears on the course website.

The TA also told me that several of the submissions would not compile, which means that the TA could not even run the tests (test1 ... test9) from the a4.java program against those solutions. Please make sure to double-check that your solutions compile and run as intended on the Prism lab computers. Also please double-check that you have submitted the best version of your code by the deadline - there's nothing more frustrating than having a perfect solution, but losing marks because a buggy older version was submitted by accident.

Also, don't forget that there is no assignment this week - you should use that time to prepare for the midterm next week. You should prepare by (1) making sure you've read the assigned readings for weeks #1 to #6, (2) comparing your solutions to the assignments with the posted solutions and make sure you understand the differences, and why you lost marks (if you did), and, (3) re-reading the lecture notes I provided and your own margin notes that you took during class. Make sure you understand everything. If you don't understand something, then either see the TA in the lab this week (he'll be hanging around at the beginning of the lab time to answer your questions), or see the prof (office hours) or ask on the forum.

The midtern will be held next week in class on Tuesday October 16, and the lab tests will be held during the scheduled lab times on Tuesday October 16, and Thursday October 18. Remember that you must attend the lab section that you are registered in for the lab tests. Also you may not miss the midterm or lab tests. And lastly, you will need to bring ID to the midterm and lab tests - don't forget.

Also, I've had several requests for additional study materials. I have dug up two old practice midterms, and two old practice lab exams, that you can use to prepare yourselves for the midterm and lab exam. Note that these practice lab tests are from previous terms, and so the terminology and format of the practice tests may differ from those used this term. But nevertheless, these practice tests should be helpful for you to test yourself on whether you understand the material.

Check-out:
Practice Midterm Test #1
Practice Midterm Test #2
Practice Lab Test #1
Practice Lab Test #2

Also, don't forget that Assignment #4 is due Friday at noon.

Lastly, I've had several requests for additional materials on both, general Java concepts, and on the advanced Java topics that we've been studying this term. Our fanastic TA Steven has put some helpful links to additional materials up on the Course Forum. Look for the article titled "Links to Java tutorials for review".

To check your grades for this course you should login to your Prism account and type the command courseInfo 1030.

To check your grades for this course you should login to your Prism account and type the command courseInfo 1030.

The notes for today's lecture are also available for download: 1030-06.pdf

To check your grades for this course you should login to your Prism account and type the command courseInfo 1030. If you enrolled late in CSE1030 and have missed Assignment #1, then the courseinfo command will indicate that your A1 mark has been Deferred.

Our illustrious TA Steven has created a very helpful guide on working from home: Remote Access.pdf.
This guide was originally written for CSE1020 students, but it applies to us as well.

Also, I've heard back from the Stacie Library, and the textbook is now on reserve under call number: QA 76.73 J38 S265 2008 BOOK.
(I am still awaiting confirmation that this is the 5th Edition of the textbook, I suspect that it is a previous edition.)

Is there any information available on how to use the Linux environment in the Prism lab (where the labs are going to be held)?

Steven Castellucci, who is one of our TAs this term, has created a tutorial on the Prism Linux environment. I think the Linux environment has been upgraded since this tutorial was first created, but most of the information in the tutorial should still be accurate.

Professor Roumani also has a tutorial that provides more of an introduction to the command-line features of Linux.

What text editor should I use?

Just to make sure that everybody knows what we're talking about, when you write a Java program, you are creating a Text File called ProgramName.java. The program you use to create this text file is called a Text Editor. Lots of text editors area available on the Prism Linux computers, and you are free to use any one that you want. (Although remember the warning I gave you regarding the text editor called Eclipse - Eclipse doesn't work well during lab tests, so you might want to use a different editor so that everything works as you're used to during the lab tests.) One that I recommend because it is easy to use, is called pico. To start pico, you would type the following at the Liniux command line: pico ProgramName.java.

Once you have created the ProgramName.java text file, before you can execute (run) the program you have to compile it. To do that you would type: javac ProgramName.java

When the compiler finishes (assuming that you didn't get any error messages from the Java compiler) you can execute (run) your program by typing: java ProgramName

What can I do to refresh my programming skills if my Java programming is a little rusty?

The first thing you should do is the assigned reading for Week #1 - you should skim through chapters 1, 2, and 3 of the textbook and review anything there that is unfamiliar to you.

The tutorial described above provides a Java program that you can type in, compile, and run. Alternatively you could also try the "Hello World" program:

/**
 * The HelloWorldApp class implements an application that
 * simply prints "Hello World!" to standard output.
 */
class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!"); // Display the string.
    }
}

Save this program with the filename HelloWorldApp.java and then compile it by typing: javac HelloWorldApp.java and run the proram by typing: Java HellWorldApp

More information about running the Hello World program on Microsoft Windows or on Linux is available from the Java website.

Next, I would try writing a couple of programs to:

1. Declare a couple of variables, A, and B. Give these variables values (A = 10, B = 20). Declare a new variable, C = A + B;. Output the value of C using the println statement. You can find more information regarding the println statement from the Java website.

My solution is available here.

2. Write a program that uses a for loop to print the numbers from 1 to 10. My solution is available here.

3. You should also refresh your knowledge of Java strings. Read the Java tutorial on Strings. Now write a program to (1) ask the user to type something, (2) read in whatever the user types, and (3) print out again. You can download my solution here.

4. Bonus: Can you change the string program so that instead of just printing in whatever the user types, it prints what the user has typed backwards? A solution is here.

What do I need to do to setup a Java programming environment on my home computer?

To do the assignments at home, you need two things: a text editor, and the Java Software Development Kit.

You can download Java for free from the Java Download Page. Follow the instructions to download and install the appropriate version of Java for your home computer.

Most operating systems come with a rudimentary text editor. For example, on windows you can use Notepad. I use vi (or the newer versions vim or gvim) but vi is not easy to learn, so I don't recommend it to others. If you Google "Free Text Editor" you'll see that there are lots of good free text editors available.

Next, why not use your text editor to type in the HelloProgram listed above, and then try to compile and run it?

Can I connect to the Prism lab computers from home, so I can test my programs, and submit them from home?

Yes. If you are using Mac OSX or Linux, then you probably already have a command line program installed called ssh. Just type: ssh USERID@red.cse.yorku.ca (where you replace USERID with your Prism user ID) type your password when prompted, and away you go.

Windows doesn't come with ssh software, but there is a great free version of ssh for Windows called PuTTY. You can download PuTTY here. Once you have PuTTY installed, connect to red.cse.yorku.ca and type your login ID and password then asked.

A perhaps better (because it supports graphics, not just text) alternative for Windows, called Xming is also available. The following instructions were given to me by our TA Steven:

Download and install Xming. Use Xming to connect to the SSH server red.cse.yorku.ca. By doing so, you will be able to use the resources of the Department server without further configuration. More information on Xming is available here.

To create an Xming connection to the CSE server, start XLaunch from the Xming program directory. Select "Multiple windows", then click "Next". Select "Start a program", then click "Next". Select "Using PuTTY", enter the SSH server red.cse.yorku.ca and your username, then click "Next". Click "Next" again. Click "Save configuration" and save the file "CSE.xlaunch" to your desktop. Double-click the file to connect to the CSE server.

Preliminary versions of my slides will be available for download from this website the morning of each lecture. Additionally, the source code for programs demonstrated in class will be made available here too.