COMP 110

First Java Program

due date: Wed, Nov. 1 by 4:00 pm


Write a Java program that will read in from the keyboard a collection
of grades for students and then find the class average on each exam.
The averages will be computed and stored along with the data that is input.
It will also compute the overall average of all grades across all students.

This program will be simple in form.  We will use one dimensional arrays 
to store the data.  The program text will be a single Java class (let's 
say class name GradeAverage) in one file (let's say GradeAverage.java).  
This class will contain inside this class at least the required main 
method -- public static void main (String[] args) -- and can have any 
other methods you want to write to help well organize your code.


INPUT FORM

For simplicity we will assume that we have 3 exam grades per student,
and that there are no missing grades. Let's assume we have some
data like this: 

   Smith Bob 45.6  87.9  71.4
   Anderson Cathy 78.7 91.3 89.2
   Jones William  71.5 53.6 98.2
   

For now we will keep data input simple... in general, input processing
can get rather complex.  Let's have the program do this: prompt the user 
for each item, one per line.  So for example, here is how the run would 
go for the above data:

   You will be entering student names and grades.
   Please enter the requested information one item per line.  
   Hit "return" after each line you type.  
   When you have run out of students to enter, give the single 
   character "." as the Last name.

   Last name? Smith
   First name? Bob
   grade? 45.6
   grade? 87.9
   grade? 71.4
   Last name? Anderson
   First name? Cathy
   grade? 78.7
   grade? 91.3
   grade? 89.2
   Last name? Jones
   First name? William
   grade? 71.5
   grade? 53.6
   grade? 98.2
   Last name? .

   <etc... the program begins computing and printing results... >

The final line containing "." is the data flag that says all student data
has been entered.  The example program "FactQuoter.java" (see the class
web page) shows the way to do this input in Java.

There will be an unknown (in advance) number of students, but we do know
there will not be more than 100 students (meaning we can make out arrays
of max size 100).  We will need several arrays to store the data -- 
first names, last names, exam1 grades, exam2 grades, and exam3 grades.
We will also need to create an array in which to store the average of
the grades for each student.  We will use common subscripts to tie it 
all together; for example, to get the information for one student 
(let's say student #8) we would examine

   firstName[8]
   lastName[8]
   exam1[8]
   exam2[8]
   exam3[8]
   average[8]

OUTPUT FORM

When you have received all the input and computed all the averages,
print out all the information in tabular form.  You will be using
"System.out.print" and "System.out.println" to do this, which work
very similar to the "Document.write" from JavaScript.  However, 
remember that HTML is a thing of the past now... you will not be 
writing out any HTML in your output. 

First print a useful header line that shows what information
appears in the columns under it.  Then, for each student, print out 
the student number in parentheses (the array index), the last name, 
a comma, a space, and the first name.  On the same line print two tabs, 
then the 3 exam grades (a tab after each one); at the end of the line 
print the average grade.  The next student will go on the next line.  
The last thing I want to see, after all students are shown, is a single
line that gives the overall average for the class on all exams.
To do this, you add up the averages stored in the average array,
and divide by the number of students.

It will look something like this:

#   Student name	ex1	ex2	ex3	avg
(1) Smith, Bob		45.6	87.9	71.4	68.3
(2) Anderson, Cathy	78.7	91.3	89.2	86.4
(3) Jones, William	71.5	53.6	98.2	74.4333

This class has 3 students.
Overall exam average is 76.377


STRATEGY

Your program will have several sections to it:

(1) a section that reads in data from the user
(2) a section that computes the needed averages and stores them
(3) a section that generates the output

Keep in mind that you will be using concepts that you already know
from JavaScript, but expressed in the somewhat new language syntax 
of Java.  So you will be processing these arrays by going through them
with for loops.  When you are in a for loop (with loop index "k" let's
say), you will think of the loop index as defining for you the student
number you are working on.  Then all the data for that student will
be found at

   firstName[k], lastName[8] 
   exam1[8], exam2[8], exam3[8] 
   average[8]

You know how to take an average for any one student... add the 3 grades 
and divide by 3.  For the overall class average, as mentioned above,
you can add up the averages stored in the average array and divide by the 
number of students. 


FINAL THOUGHTS

Remember to use good programming style... use named constants where 
appropriate, choose meaningful variable names, have a beginning block
comment as well as smaller comments throughout, design a clear algorithm,
make it all indented and readable.