How can I retrieve or access the 'courses' data from this Java method?

Courses
1

I’m a beginner in Java and I’m stuck on my first coding task. I’ve got a Student array that holds a Course array, but I’m running into a NullPointerException and can’t figure out why. Here’s my code:

public Student[] processStudentData() {
    Scanner fileReader = null;
    try {
        fileReader = new Scanner(new File("student_data.txt"));
    } catch (FileNotFoundException e) {
        System.out.println("Can't find or open student_data.txt file.");
        System.exit(0);
    }

    int studentCount = fileReader.nextInt();
    int hourlyTuition = fileReader.nextInt();

    Student[] studentList = new Student[studentCount];
    for (int i = 0; i < studentCount; i++) {
        String name1 = fileReader.next();
        String name2 = fileReader.next();
        int idNumber = fileReader.nextInt();
        String tuitionStatus = fileReader.next();
        int courseCount = fileReader.nextInt();

        Course[] courseList = new Course[courseCount];
        for (int j = 0; j < courseCount; j++) {
            String subject = fileReader.next();
            String courseCode = fileReader.next();
            int credits = fileReader.nextInt();
            String letterGrade = fileReader.next();
            Course newCourse = new Course(subject, courseCode, credits, letterGrade);
            courseList[j] = newCourse;
        }
        Student newStudent = new Student(name1, name2, idNumber, tuitionStatus, courseCount, courseList);
        studentList[i] = newStudent;
    }
    return studentList;
}

The input file looks like this:

3 345
John Doe 123456 Y 2 
English ENG101 3 B
Math MTH202 4 A

Jane Smith 789012 N 1
History HIS303 3 A

I’m trying to get the course info for each student. Any ideas what’s causing the error?

2

yo ethan, ur code looks solid but that nullpointerexception is sneaky. maybe check if ur actually calling processStudentData() and saving the result? also double check ur file path for student_data.txt. if ur still stuck, try adding some System.out.println() to see where it crashes. good luck dude!

3

Based on your code, it looks like you’re already correctly parsing and storing the course data for each student. The NullPointerException you’re encountering is likely occurring elsewhere in your program when you’re trying to access this data.

A few things to check:

  1. Ensure you’re calling the processStudentData() method and storing its return value.
  2. Verify that you’re accessing the courses through the Student object, not directly from the array.
  3. Double-check that your Student class has a getter method for courses, like getCourses().

If you’re still having issues, it would be helpful to see the part of your code where you’re trying to access the course data. That’s likely where the NullPointerException is occurring.

Also, make sure your file path for ‘student_data.txt’ is correct. If the file isn’t found, your program will exit before creating any Student or Course objects.

4

Hey there, Ethan85! :wave:

Your code looks pretty solid for a beginner. I’m curious though - where exactly are you getting that NullPointerException? :thinking:

From what I can see, you’re doing a good job of reading the file and creating the Student and Course objects. But sometimes these pesky exceptions can pop up in unexpected places.

Have you tried adding some print statements throughout your code to see where it might be failing? That could give you a better idea of what’s going on.

Also, I’m wondering - how are you using this processStudentData() method in the rest of your program? Are you calling it and storing the result somewhere?

Oh, and one more thing - make sure your student_data.txt file is in the right directory. I’ve been caught out by that before!

Let us know if you figure it out or if you need more help. We’re all learning here, right? :blush: