A few words of advice

[LaevisX]

Having taken 148 last term, and wishing to procrastinate for a few minutes right now, I think I can offer some advice regarding assignments you guys might find useful (or not ;D)

I'll talk about our A1 first.  It was out of 50, with the following distribution:

10/50: Correctness (automarking)

Not much you can do here, except test and test and test your program.  Definitely test extreme cases (ex. empty list, lists with 1 element, 2, 3, and many).  This really depends on your assignment of course, but make sure to test extreme cases.

Another thing that got people burnt in this section, was the difference between empty strings and null strings.  These are 2 different beasts, so make sure that you know the difference, and more importantly, that your _code_ knows the difference!

20/50: Interface Design

It is imperatively that _only_ methods that are supposed to print, will print.  Many people got burnt to a crisp for this.

For example, say you have a class that holds and manipulates data (say, Queue.java), and a class (say A1Driver.java) that uses/tests Queue objects.  And in the instructions, they just say something like, if user types in "getthis", the program will print "fukyou", without specifying which class should do the getting and which should do the printing, I'll tell you now that they should _both_ be done by A1Driver.java.  Data structures (i.e. Queue.java) as a rule do not read user inputs nor do they do any kind of printing.  If you're ever in doubt, compare the class you're making with a similar type of class in Java, and see what that class does.  Look at the Vector class (a data structure like Queue.java).  It does not print anything, right?  If you want to print the elements from a Vector object, you use the elements() method which returns an Enumeration, then print that Enumeration in A1Driver.java.

10/50: Internal Design & Style

This is how "tight" your code looks.  Make sure it looks tidy.  Somethings to keep in mind:
1) Your program must be printable (i.e. when printed, no ugly word wraps happening.  If you have really long lines in your code, break them at logical points and indent appropriately in the next line.
2) Logical use of white space makes your programs more readable (and keeps the marker happy).
3) Absolutely no magic numbers or text.  Use constants.
4) Remember, just because your program works, doesn't mean it's good code.  If you want to see if your code is good, give it to a friend to look over and see if they can understand what you are trying to do.
5) Comments... very important, but the book explains better than I can hope to do here.

10/50: Testing

More or less what I said before, for testing your program.  Cover all extreme cases for all variables.

I guess I can offer my help to you guys if you need advice, but don't expect me to read your assignments and debug your code.  I can answer general questions about course material, tutorial stuff, and coding.  Since I don't expect I'll be around this forum often, feel free to email or message (don't check as often though) me.  Or if there already is a topic here you want my advice on you can just email me to let me know.

I'm offering to do this cuz I'm not taking any CSC courses this term and wouldn't mind having a little exercise to keep the rust away

And bookmark this if you haven't already:
java.sun.com/products/jdk/1.2/docs/api/index.html

Cheers & good luck

[Brutal_Chicken]

Ok then Mr. Laevis X, if that is you're real name. ;D

Which is more efficient?

Creating a primitive data type to hold the result of a method then use it in another method or simply put it all on one line:

String s = methodThatReturnsString();
anotherMethodThatUsesString(s);

OR

anotherMethodThatUsesString(methodThatReturnsString());

Generally, it's clearer in the first 'style' but a lot more straightforward in the second. The first uses extra space, no matter how small it may be, while the second takes more ram. Which is generally preferred?

Also, to cut down on useless comparisons, like taking user commands in A1Driver, I simply used one while loop that will continue running until the 'end' command is entered by the user. It works fine and all but I was wondering if using two while loops instead where one is inside another might be quicker since Java still checks the other if statements.

What I'm doing:

while {

if (something)

if (another thing)

if (something else)
.
.
.
etc
}

What I was thinking of:

boolean commandEnd = false;
while (commandEnd == false) {
   while (!(input.equals("end"))){
   
   if (something) {
      ...
      break;
   }
   if (something else) {
      ...
      break;
   }
   ...
   etc
  }
  commandEnd = true;
}

Will this shave off some unnecessary operations?

[LaevisX]

Of course that's my real name, my parents freaked out the minute they saw me

Dad: My God, what the hell was that?!
Mom: Eeewww, its all green and icky, like a frog...
Dad: A frog... like a X.laevis?
Mom: I like that name... let's call him LaevisX honey!
Me: Waaaaaaa!

Ok, enough about my childhood, back to the issue..

-----------------------------
Re: data type question
The answer is it depends.  There are 2 things to consider: Efficiency and readability.

If it is a simple statement, like:
computeLength(getDot(x1,y1), getDot(x2,y2));
Then one statement would be recommended (more efficient, easy to read)

If it is something like:
computeArea(computeLength(getDot(x1,y1), getDot(x2,y2)), computeLength(getDot(x3,y3), getDot(x4,y4)), computeLength(getDot(x5,y5), getDot(x6,y6)));
(Confusing to read)

Then you're better off doing:
int length1=computeLength(getDot(x1,y1), getDot(x2,y2));
int length2=computeLength(getDot(x3,y3), getDot(x4,y4));
int length3=computeLength(getDot(x5,y5), getDot(x6,y6));
computeArea(length1, length2, length3);
(Less efficient, easier to read)

In general, readability takes precedence over efficiency, considering we are in the age of the gigahertz computers

Not that efficiency counts for nothing! When going through your code, maximize efficiency first, _then_ maximize readability.

-----------------------------
Re: while/if question

Just comparing your two ideas, I'd say the second one is not a good one.  There is redundency in the function of the two while loops, and some -- not all, mind you -- people are averse to the idea of using break statements, since they can always be avoided.

I'd suggest a mix of the two ideas you suggested, like so:

boolean commandEnd=false;
while (commandEnd==false) {
  if (something) {
  } else if (something else) {
  } else if (something else) {
  ...
  etc
  } else if (user types "end" or whatever) {
      commandEnd=true;
  }
}

By using "else if"'s, I believe Java will skip over all the other "else if"'s past the one that's true.

[Sylph]

LaevisX,
is it better to have a really big A1Driver (the required class), or is it better to make a helper class to put all the methods? as well, what would be a good name for a helper class.. "Helper"?

[bladehunter]

NOTE TO ALL WORKING ON A1

From the mouth of my prof, Paul Gries.......

"If your main method in A1Driver is more than 40 lines long, marks from your style will be deducted."

Hope that answers some helper method questions....

[LaevisX]

Sylph said:

LaevisX,
is it better to have a really big A1Driver (the required class), or is it better to make a helper class to put all the methods? as well, what would be a good name for a helper class.. "Helper"?

It is generally _not_ a problem to have a big class.  What _is_ a big problem are big methods.  As bladehunter just pointed out, your main method (and any other methods for that matter) should not exceed some 40 odd lines (not including comments, of course).  If a helper method becomes too long, break it down and use another helper method to help the helper.

Helper classes are not usually necessary for the purpose you mentioned.  More likely they are needed when you have multiple classes that do similar functions.  For example, if you have multiple classes that output html files, instead of having all of them print the same header and footer information, you can have them reference methods from a helper class (ex. HtmlHelper.java) with methods like printHeader() and printFooter(), to save on redundency.

[Brutal_Chicken]

Ahh crap.