Final MCIT pizza party Tuesday April. 27, Levine 307, 5:00 PM

Students are encouraged to attend. Class today may begin slightly later than usual (but probably won't).

I have posted a NewParserTest.java, which is to be used for grading purposes. If you see any serious flaws in this test, please respond before we do all the grading.

The second part of Assignment 5 is now posted.

Minor corrections to first part:

• The class name is LogoInterpreter, not Interpreter.
• DrawingCommand is an abstract class, not an interface.
• DrawingCommand has an apply() method, not an execute() method.

I have posted the first part of Assignment 5: Interpreter, along with some starter code.

All public methods in DrawingCanvas must be public synchronized void, not just synchronized void. I have made this correction in the posted code; if you have already downloaded it, just make the correction yourself.

My apologies for being slow to get this posted; I had some annoying Exceptions that I had a lot of trouble tracking down. Macintosh users: You may have problems with this starter file, particularly in initial window size.

Next MCIT pizza bash tomorrow, Wed. Feb. 18, Levine 315, 6:15-8:15pm

(For students in the MCIT degree program. We'll try to make the next pizza party more inclusive.)

I have a page of Final Parser Corrections. While these are not as serious as I initially feared, for this and a couple of other reasons I have decided to delay the due date one more day--before midnight, Tuesday, Feb. 17.

I still intend to hand out the next assignment tomorrow.

"Today a usual technique is to make a program and then to test it. But: program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence."
   -- Edsger Dijkstra, in The Humble Programmer

My test class contains the lines

  public void testBlock() {
        use("[ \n penup \n pendown \n ] \n");
        assertTrue(parser.command());

That should be assertTrue(parser.block());

Since my parser passes all the tests, you might conclude that there is a bug in my parser--that it accepts a <block> as a <command>. You would be right.

I've corrected (and re-tested) DrDavesTests.java on the website.

Now available:

• New version of Parser Assignment (main changes: Adding pictures for <expression>, <term> and <factor>, and a later due date)
• New version of Parser Grammar (rule for <program> added)
• Completely new Parser Addendum, containing much valuable information about how to do this assignment.
• Starter code Parser.java and ParserTest.java

In response to several people's questions:

• Yes, Set is an interface, not a class.
• No, you don't write your own! You use one of the existing implementations. See the Java API and just pick one. (Example: Set mySet = new TreeSet();).

(4:17 p.m.) I've just posted a corrected version (sigh) of BinaryTree.zip. Thanks, Dave!

(4:49 p.m.) I've posted corrected versions of Assignment 4 and the revised grammar. Thanks, Charlie!

I've posted my code for the BinaryTree ADT, as BinaryTree.zip.

At the request of my TA, I have extended the due date for the third assignment by one day (before midnight, Feb. 6), to give you an opportunity to look at my binary tree class, especially the test classes. Your code should pass all tests.

I defined <procedure> ::= "to" <name> { <variable> } <eol> [ { <command> } ] "end" <eol>
The brackets are unnecessary; a simpler, equivalent form is:
<procedure> ::= "to" <name> { <variable> } <eol> { <command> } "end" <eol>

I've posted a new version of RecognizerTest.java. There are two changes:

• I've made the changes to the remainder method as indicated in Notes on Recognizer Assignment, and
• I've filled in the code for the testFactor() method, which I had overlooked before.

When you submit assignments, please follow these conventions:

• Name your submission file as userid-n, where userid is your user id and n is the assignment number (for example, matuszek-2).
• Put your files in a single directory
• Do not generate javadoc

Turn in the zipped directory via Blackboard.

If you have already submitted your second assignment, you do not need to resubmit--but please follow these conventions for future assignments.

Story at: ComputerWorld

Serious information at: Symantec

First corrections to Assignment 2 (sigh):

• One of the leftChild fields in the BinaryTree class should be named rightChild.
• The setLeftChild and setRightChild methods should return void.
• The public int evaluate() method in the ArithmeticExpression class should not take an argument.

I have made these corrections in the assignment itself.

Eclipse fix: If Eclipse won't open for you or isn't behaving correctly, the problem may be that it's workspace has become corrupted.

When the application says"Completing Installation" when you activate it, it's actually creating some files in your home directory under ~/workspace. If you already have the files in a good ~/workspace directory, it checks to make sure that it can use them, then it opens. You can either remove or change the name of the ~/workspace directory, then restart Eclipse. It will create a new ~/workspace and continue to function.

Caution: The workspace is where Eclipse saves your files. If you have project files in your workspace, you may wish to recover them before deleting the workspace.

(Thanks to Karl E. Morris for finding this solution.)

Several people had suggestions on how to get "soft tabs" in Eclipse. Here are the suggestions that seem to work for me:

• To turn existing tabs into spaces,
  1. choose Preferences -> Java -> Code Formatter -> Style and uncheck Insert tabs for indentation, not spaces
  2. Select the code, right-click in it and choose Source -> Format (or hit Command-Shift-F)
     
     
• To turn tabs into spaces as you type, choose Preferences -> Editor -> Typing -> Insert space for tabs