CODEWITHSUNDEEP
c#arrays
dwwilson66
dwwilson66

Reputation: 7066

How to populate array lists in c#?

I have an assignment to read a file of student records, then calculate and display the final grade for each course. As an old procedural programmer, I'm having a hard time with figuring out the "proper" (e.g., most OO) program flow, given the UML from which we're supposed to start. A big problem is that this is my first time implementing Array Lists, and I'm still a little fuzzy on practical examples, even after perusing the Java Tutorials and a bunch of online samples. I think the end-of-semester brain fuzz is preventing me from applying those examples to this assignment.

Here's where I am so far:

My main method consists of

FinalStudentGrade finalGradeReport = new FinalStudentGrade();
finalGradeReport.MainMethod();

which calls Students.PopulateStudents(@"grades.txt") to display the grade report. PopulateStudents() reads the data file, creating a student object through the constructor, and based on the following data member:

string nameFirst;
string nameLast;
string studentID;
ArrayList Earned; 
ArrayList Possible; 
float average;
string letterGrade;

The PopulateStudents method reads the file, creates a Student object for each line in the file, including a calculated average and letter grade. Each of these students then need to be added to List<Student> theStudentList; 

class Students
{
    List<Student> theStudentList;
    public bool PopulateStudents(string @sourceData)   
    {
        String sourcePath = sourceData;
        theStudentList = new List<Student>();
        bool success = true;
        try
        {
            StreamReader inputReader = new StreamReader(sourcePath);
            while (inputReader != null)
            {
                String inputLine = inputReader.ReadLine();
                char delim = ',';   
                String[] inputValues = inputLine.Split(delim);

.... and I'm Stuck ....

I was about to define nameFirst = inputValues[1];, nameLast = inputValues[2];, studentID = inputValues[0]; etc., but then I realized that I'm not using the constructor to create the Student object.

Do need to create Student.nameFirst=..., then populate theStudentList with those objects? Or can I just define theStudentList[recordCounter].nameFirst (defining a recordCounter first, of course) because theStudentList is being instatiated as List<Student>();? What's the best way to proceed with that, and am I visualizing the program flow between classes in a good way?

Upvotes: 0

Views: 173

Answers (2)

krillgar
krillgar

Reputation: 12805

Just a little addendum to make it even simpler to read than D Stanley's answer:

theStudentList.Add(new Student {
    nameFirst = inputValues[1],
    nameLast = inputValues[2],
    studentID = inputValues[0]
});

Upvotes: 1

D Stanley
D Stanley

Reputation: 152501

Well, I don't see a constructor defined, so I'm assuming you didn't define one that takes paramters. If that's the case, you can either construct the object first, then set the properties:

Student s = new Student();
s.nameFirst = inputValues[1];
s.nameLast = inputValues[2];
s.studentID = inputValues[0];

or use initialization syntax

Student s = new Student() {
    nameFirst = inputValues[1]
    nameLast = inputValues[2]
    studentID = inputValues[0]
    };

If you did define a constriuctor (say one that takes the three properties you mentioned), then just use the constructor:

Student s = new Student(inputValues[1], inputValues[2], inputValues[0]);

then just add the created student:

theStudentList.Add(s);

Upvotes: 5

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