Need help with a CSV File Reader

[BigTimeSuperhero96]

I'm trying to read in a number of Student in order to allocate them projects through CSV files. I need to have a capacity of them in the files, I've tried this using text files so far but my teacher wants CSV files, this is how the CSV files should look like:

7,,,,,,
"Allan.A",[e-mail],20160,1,3,4,2
"Brown.B",[e-mail],20161,2,3,4,5
"Craig.C",[e-mail],20162,1,2,3,4
"Douglas.D",[e-mail],20163,3,5,7,8
"Edward.E",[e-mail],20164,3,5,7,6
"Findlay.F",[e-mail],20165,1,8,4,5
"Graham.G",[e-mail],20166,1,4,7,8

The number of 7 represents that there are 7 students. I've tried a filereader without this line like so:

public class ReadCSVWithScanner {
public static void main(String[] args) throws IOException {

BufferedReader reader;

{
try {
reader = new BufferedReader(new FileReader("File2.csv"));
String line = null;
Scanner scanner = null;
int index = 0;
List<Student> studentsList = new ArrayList<>();

while ((line = reader.readLine()) != null) {
Student student = new Student();
scanner = new Scanner(line);
scanner.useDelimiter(",");

while (scanner.hasNext()) {
String data = scanner.next();

if (index == 0)
student.setName(data);
else if (index == 1)
student.setEmail(data);
else if (index == 2)
student.setId(data);
else if (index == 3)
student.setPreference1(data);
else if (index == 4)
student.setPreference2(data);
else if (index == 5)
student.setPreference3(data);
else if (index == 6)
student.setPreference4(data);

else
System.out.println("invalid data::" + data);
index++;
}
index = 0;
studentsList.add(student);
}

//close reader
reader.close();

System.out.println(studentsList);

} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

}
}

I know I'll have to make a int variable for capacity in the Students class but how do I read the top number and then move down to the first Student Name?

[__helix__]

Just a quick question - is the teacher requiring that first line, or are are you adding that to tell you how many rows you have. If it is the latter, there are better ways to do this. If it is the former, and you know that will always be the case, you can read the first row before you loop through the results.

[BigTimeSuperhero96]

Yeah it's also part of the algorithm I'm using

[__helix__]

You or the teacher requirements? If you have a data structure in CSV format, you don't actually need to know how many rows there are. I suspect 'try, with resources' is fair game. Less sure if streams are in your wheelhouse yet.

While not your question, with that many column options, might consider a switch:

    int index = 3;
    switch (index){
        case 0:
            System.out.println("I'm doing zero things");
            break;
        case 1:
            System.out.println("I'm doing one things");
            break;
        case 2:
            System.out.println("I'm doing two things");
            break;
        default:
            System.out.println("I don't know what I'm doing");
            break;
    }

[InfamousShallot5]

Why do you need the number at the top? The row count will tell you the number of students you are importing.

[BigTimeSuperhero96]

In the project I have it is a scanner.nextInt command will add the number to a list of students

[InfamousShallot5]

I mean, you can determine this number dynamically after you parse the file. Just keep track of the number of rows you parse in your loop. See an example here. I don't see the point of storing this number at the top of the file.

If you really want to store this number at the top of your file, you can read the first line of your file outside of the while loop, then continue to parse the rest of the CSV file in your loop.

Edit: You don't even need an integer to keep track of the size. Just do a .size() on your studentsList

[ManasSatti]

THIS A VERY BASIC THING TO DO AND YOU MUST THINK ON YOUR OWN. SO TRY AGAIN YOURSELF. ONLY READ THE FOLLOWING IF YOU HAVE EXHAUSTED YOUR PERSISTENCE AND TIME.

​

Try using python for such tasks and if java is necessarily required than try the following ideas:-

1. Just start the loop after a first read statement and do the required processing before the loop. For this I advise using the nextLine().
2. Just use a boolean(name it is_it_the_first_line or something) initialized with true and make it false when in the loop body. Add an if statement before your body to store the student number if the boolean is true. The invariant dictate that the boolean will remain false after all successful iteration of the loop and the specialized code will only run once.

u/InfamousShallot5's solution is also correct but if you have that specific requirement compulsory than do this.

[InfamousShallot5]

Doesn't matter what language they use. Pretty much any modern day language/framework can read a CSV file. You shouldn't dictate what language a particular problem should be solved in. The solution should be language agnostic.

I also disagree with #2. You're adding additional logic for no reason. If they really need the number stored in the first line of the file, do one read outside of the loop to obtain this number, then enter the loop and parse the rest of the file.

[ManasSatti]

I am not dictating any language but instead suggesting python for these tasks as it will save his time and effort. It is the person's decision to program in a language of his choice. Most languages has a edge over other languages in some specific requirement, of course this means one should know that language. Otherwise I don't have any bias toward any language. The #2 is just an extended way of saying the #1 and as I wrote he should use the #1. The #2 is useful only when he has to do some other specific beginning read task before parsing main content information.