Description
1. Write a program Welcome.java that expects two string command line
arguments, a first name and a second name. The program prints out
on one line “Hello first second.”, and on the next line, “Is that first
SECOND or FIRST second?” where first and second are the first and
second command line arguments, and FIRST and SECOND are the first
and second arguments printed in all upper case letters. Do not print any
extra spaces, even at the beginning or ends of the lines. Do not worry
about too many or too few command line arguments. For example, if the
command line arguments are “Joe” and “Blow”, the program should print
out:
Hello Joe Blow.
Is that Joe BLOW or JOE Blow?
2. Write a program Circle.java that prints out the area of a circle whose
diameter is specified as the only command line argument. The result
should be formatted with four digits after the decimal point, and no extra
characters or spaces before the decimal point. Don’t include any extra
characters in the output. The command line argument may be written as
an integer or as a floating point number. Do not worry about too many
or too few command line arguments, or the command line argument not
being a number. For example, if the command line argument is specified
as 2, the output should look like:
3.1416
Hint: The area of a circle of radius r is πr2
.
Hint: You can use Double.parseDouble(s), where s is a string, to turn
a string representing a floating point number into the double it represents.
Using Command Line Arguments
The command line of a Java program is whatever is placed on the command line
after java programname. Each word or number placed there is made a separate
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command line argument when the program is run. If you want multiple words,
or text with whitespace or special characters, to be treated as a single argument,
you can surround it with single quote characters (’). So for example, if your
command line is:
java Program 42 hello there ’this is a test’
when the program is run, it will receive 4 command line arguments: “42”,
“hello”, “there”, and “this is a test”.
Inside a Java main method
public static void main(String[] args)
the variable args holds all the arguments passed to the Java program on the
command line as strings. You can access the first command line argument as
args[0], the second as args[1], and so on. We will learn why this works in a
few weeks, but for now, just use that syntax to access command line arguments.
Submission and Verification
You must submit your project from any one of the student unix servers. Make
sure the version of your program source files you wish to submit is on these
machines (your files are shared between all of them, so any one will do), then
cd to the directory holding your source code and issue the command:
submit COMP90041 lab1 Welcome.java Circle.java
Important: you must wait a minute or two (or more if the servers are busy)
after submitting, and then issue the command
verify COMP90041 lab1 | less
This will show you the test results and the marks from your submission, as well
as the file(s) you submitted.
If your output is different from the expected (correct) output, when you
verify your submission you will see the differences between your output and
what was expected. This will be shown as some number of lines beginning
with a minus sign (-) indicating the expected output and some number of lines
beginning with a plus sign (+) presenting your actual output. There may also be
some lines beginning with a single space showing lines you produced that were
as expected. Carefully compare the expected and actual lines, and you should
be able to find the error in your output. The actual and expected outputs will
be aligned, making it easier to find the differences. Some differences are hard to
spot visually, however, such as the difference between a capital O and a zero (0)
or the difference between a small l and a capital I and a one (1). This depends
on the font you are using. If the only difference between actual and expected
output are in whitespace or capitalisation, you will receive partial credit; this is
shown in your verification feedback.
Also note that the differences shown only reflect program output, not input.
Therefore, if your program outputs a prompt, waits for input, and then outputs
something else, the differences shown will not include the input, or even the
newline the user types to end the input. In that case, the prompt would be
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shown immediately followed by your program’s next output (which may be
another prompt), on the same line. This is as expected.
If your program compiles on your computer but the verification output reports that your program does not compile on the server, you may have failed to
submit all your files, or you may have named them incorrectly. It is also possible
that your program contains a package declaration. This would appear near the
top of your .java file. If you have such a declaration, your program will probably
not compile, so you should delete any such declaration before submitting.
If the verification results show any problems, you may correct them and
submit again, as often as you like; only your final submission will be assessed.
If your submission involves multiple files, you must submit all the files every
time you submit.
If you wish to (re-)submit after the project deadline, you may do so by adding
“.late” to the end of the project name (i.e., lab1.late) in the submit and
verify commands. But note that a penalty, described below, will apply to late
submissions, so you should weigh the points you will lose for a late submission
against the points you expect to gain by revising your program and submitting
again. It is your responsibility to verify your submission.
Late Penalties
Late submissions will incur a penalty of 1% of the possible value of that submission per hour late, including evening and weekend hours. This means that
a perfect project that is a little more than 2 days late will lose half the marks.
These lab exercises are frequent and of low point value, and your lowest lab mark
will be dropped. Except in unusual circumstances, I will not grant extensions
for lab submissions.
Academic Honesty
This lab submission is part of your final assessment, so cheating is not acceptable. Any form of material exchange between students, whether written,
electronic or any other medium, is considered cheating, and so is the soliciting
of help from electronic newsgroups. Providing undue assistance is considered as
serious as receiving it, and in the case of similarities that indicate exchange of
more than basic ideas, formal disciplinary action will be taken for all involved
parties.
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