Due: Thursday, February 12, when labs close.
Files to turnin:
memo.txt
DoubleArithmetic.java
PhoneBill.java
LinearEquation.java and
Temperatures.java
Some of these problems are quite straightforward. Some are subtle.
memo.txt .
Remember to pay attention to spelling and grammar in your memo. Since the spell checker in emacs isn't working yet, could consider pasting the contents into MSWord (available on the lab machines), checking the spelling there and then pasting back into emacs. Clumsy, but maybe worth the effort. Or get a friend to proofread.
Temperatures is discussed in Chapter 2 of
JOI. You can find the source code on the JOI web page or the CD.
Find all the places in Temperatures.java
in which a message is sent to an
object that's
not
a Terminal . (There are so many of those that
including them in this discussion would be tedious.) For each one,
identify
LinearEquation.java instead of lines from
BankAccount.java .
In class we'll discuss what this code does (the semantics) but you should be able to answer this question just from the structure on the page (the syntax).
Your output match the sample output in the text exactly (except for the question marks at the end - provide the right answers there) since we will use our computer to see whether the output from your program is exactly the same as the output from a correct program. So to get full credit, you need to make sure that the program prompts are just what we've specified. It's not enough to get the correct numerical answers.
Here is the sample output (copied from JOI). You can cut the prompts from this web page and paste them in as quoted strings in your Java program. That's a way to make sure they are right, with no chance for a typing error. The program's output is in bold face.
Basic rate (in dollars): 30 Cost per message unit (in cents): 5 Number of message units: 101 Phone bill is: $35.05 Amount willing to spend (in dollars): 40 Maximum number of message units: ???
Note: optional problems really are optional. We don't add the points you earn on them to your score for the homework (if we did, they wouldn't be optional). We'll keep track of the optional work you do, and if at the end of the semester you're just on the borderline, say, between an A and an A-, optional work can tip the balance. But they won't help if you're on the borderline between a C and a C+. If that's where you find yourself you should have spent more time on the regularly assigned work!
> From: a classmate > To: eb@cs.umb.edu > Subject: hw2 > Date: Thu, 5 Feb 2004 18:34:02 -0500 > > I have a question about homework 2 part 2 where you ask us > to identify all the places in Temperatures.java in which a > message is sent to an object that is not a Terminal. I was > wondering if this included messages sent to a terminal > object whose information is a message to an other object? > Such as the line of code that follows. > > terminal.println( c2f.compute( 0.0 ) ); > > Would you want the compute message sent to the > LinearEquation object called c2f identified even though it’s > the information being sent with the println message? > Thank you for you time, Sean. Good question. println is a message sent to the Terminal object terminal so you need not discuss it. But c2f.compute is a message sent to c2f. The corresponding method returns the information the println nessage needs to send along to the Terminal. Remember that Java is case-sensitive, so Terminal and terminal are different identifiers. You use the wrong one in your question where you speak of a "terminal object". You should say "Terminal object" or "the terminal".