Honoring the API is an important part of software
development. In cs110 that means (among other things) that when you
write code that must interact with code you've been given, you may
only change the files that you are asked to change. If you turnin too
much you have not followed instructions. At best you will lose points
for just turning in unnecessary code. At worst, your code won't run
when we test it with our classes.
Testing is an important part of the software development
process. So everything you write must be tested and you must write
about your testing in your memo, even if the exercise does not
explicitly ask for it.
-
JOI Exercise 6-2 (Exploring Juno). You can do this exercise without
copying and compiling code. Just download file juno.jar and run Juno with the command
java -cp juno.jar Juno
From: Ethan Bolker
Subject: Java 1.4 / Java 1.5 incompatibility
Date: Fri, 2 Apr 2004 19:57:16 -0500 (EST)
If you try
java -cp juno.jar Juno
with Java 1.5 and the original jar file the link above
you get an error.
I have replaced that jar file with one that works both with
Java 1.4 and Java 1.5.
-
JOI Exercise 6-4. You will have to create the new class UserTable,
modify Juno.java, and modify the source code in one other class.
From: Ethan Bolker
Subject: what needs to be modified
Date: Tue, 6 Apr 2004 13:34:59 -0400 (EDT)
You don't in fact have to modify anything other than Juno.java to
use the new UserTable class. But you may modify some other file if you
decide to. Just be sure to turn it in.
If you have rewritten User.java in order to add a toString() (for
finger) then turnin that file.
We will test your Juno with all the classes you turnin, using ours
when you haven't given us one. But you will lose points if you turnin
files you have not changed, or if your design calls for changes in
many places when just a few would suffice.
> From: a classmate
> To: eb@cs.umb.edu
> Subject: Homework8:6-4
> Date: Tue, 6 Apr 2004 09:07:31 -0700 (PDT)
>
> Dear Professor,
>
> As specified in No.2 question, we are supposed to modify
> UserTable.java, Juno.java and one more source file. But I have a
> question:
>
> I have done with UserTable and Juno, and I put them in test with
> other classes. My modification works without changing one more
> source file.
>
> I don't know if I have to change the unknown source file?
-
Explain how the stripComments method in class Shell does its
job by walking through the code as it processes the newfile command in
the example that follows. You'll have to look up some things in the
String API to answer this question.
Welcome to mars running Juno version 6
help, register, <username>, exit
Juno login: register eb Ethan Bolker
Juno login: eb
mars> newfile memo.txt my memo for hw8 # always start this first
mars> type memo.txt
my memo for hw8
mars> logout
goodbye
Juno login: exit
Your solution (in memo.txt) should show the state of the various
Strings and StringTokenizers at each step.
- Explain why "logout" does not appear in the list when you ask for
help at the Juno shell prompt. (You will have to find the right place
in the code to answer this question.)
- JOI Exercise 6-9 (alias). Your answer should be in file
AliasCommand.java.
From: Ethan Bolker
Subject: hw8
Date: Sat, 3 Apr 2004 07:45:02 -0500 (EST)
Excellent questions!
> From: a classmate
> To: eb@cs.umb.edu
> Subject: hw8
> Date: Sat, 3 Apr 2004 01:32:22 -0800 (PST)
>
> hello Prof. Bolker,
> I have got a question about the Ex. 6-9 (alias), can we modify the
> declaration of any method in ShellCommandTable from private to
> public, for ex. if I want to change the access modifier of install
> method to public, is it allowed.
In general, a solution that does not change an API is usually better
than one that does. But if you can't solve a problem without a change,
or if the solution without the change is really long and ugly, then
it's better to change the API - as long as you discuss the change with
the other programmers on your team. In thiscase that means writing
about your design decision in your memo.
> Moreover, I wanted to know whether the alias for the command
> created will be valid through out the Juno session in which it is
> created, or only for the user who creates it.
Throughout the session.
From: Ethan Bolker
Subject: alias in Juno
Date: Sun, 4 Apr 2004 08:43:07 -0400 (EDT)
Yes
> From: a classmate
> To: eb@cs.umb.edu
> Subject: hw8
> Date: Sun, 04 Apr 2004 03:20:05 -0500
>
> Hi, Prof. Bolker
>
> I have a question about AliasCommand.java.
> After users create a newname for an existing command, will the old name
> still work as before?
- JOI Exercise 6-19 (finger). Use the version of Juno you wrote for
problem 2.
-
Optional.
Modify Shell.java so that when the comment character is escaped
with a backslash it does not start a comment, as in this example:
Welcome to mars running Juno version 6
help, register, <username>, exit
Juno login: register eb Ethan Bolker
Juno login: eb
mars> newfile comment.txt '\#' is Juno's comment character. # OK?
mars> type comment.txt
'#' is Juno's comment character.
Anywhere but before a '#' the '\' is an ordinary character.
-
Optional.
Rewrite Juno version 6 so that it uses Java 1.5 collections. Every
unchanged line of code should have the same line number in its file
after you have made the necessary changes. You should probably be able
to do this using extra blank lines judiciously, since the iteration
idiom in Java 1.5 uses fewer lines than its 1.4 counterpart.
A good way to start is to compile the existing code with the Java 1.5
compiler and the -source option to see where warnings occur.
Prof. Campbell and I will consider using the best of the submissions
to start the process of converting all later releases (in chapters 7,
9 and 10).