ArrayIndexOutOfBoundsException:4

[Alzecha Maris]

Hey there, I'm having a bit of trouble with this project:

We're given a text file of 5 students, with 4 number grades following each name in a separate line. We have to use our main method to read the file, then perform calculations in the gradebook class. However, from what others in class have been saying the method we're using is archaic at best, involving Parallel arrays. We don't really seem to have any other option though, so I'm making due with what I can. But near what I'm hoping is the end of this code, I've encountered a problem, where it says the index that contains the grades for students is out of bounds.

I've rewritten the readFile method in my main in quite a few different ways, but no matter what I still get these errors. Could anyone help me understand what's going on? I'll post everything I can.
I also apologize if I'm a bit slow/incapable with this, this is my first time coding java in months unfortunately.

import java.util.Scanner; import java.io.*; public class GradeBookDemo { public static void main(String[] args) throws IOException { // Create a new gradebook object Gradebook gradeBook = new Gradebook(); //Read StudentInfo file for names and test scores using readFile method readFile(gradeBook); //Output Student data for (int index = 1; index <= 5; index++) { System.out.println("Name: " + gradeBook.getName(index) + "\tAverage Score: " + gradeBook.getAverage(index) + "\tGrade: " + gradeBook.getLetterGrade(index)); } } // This method reads from the StudentInfo file public static void readFile(Gradebook gradeBook) throws IOException { int nI = 0; // Name index int gI = 4; // Grade index // Create a string array to hold student names and another for grades double[] grades = new double[gI]; // Access the StudentInfo text file File sFile = new File("StudentInfo.txt"); // Create a scanner object to read the file Scanner inputFile = new Scanner(sFile); // Read StudentInfo for(int student = 1; student <= 5; student++) { String name = inputFile.nextLine(); gradeBook.setName(student, name); for (int test = 0; test < 4; test++) { grades[test] = inputFile.nextDouble(); } } // Close the file inputFile.close(); } }

public class Gradebook {
    
    // Declare fields
    private final int NUM_STUDENTS = 5;
    private final int NUM_TESTS = 4;
    // ArrayList for names of students - 5 in total
    private String[] names = new String[NUM_STUDENTS];
    // Array to store letter grades
    private char[] grades;
    // array to store each student's scores
    private double[] scores1 = new double[NUM_TESTS];
    private double[] scores2 = new double[NUM_TESTS];
    private double[] scores3 = new double[NUM_TESTS];
    private double[] scores4 = new double[NUM_TESTS];
    private double[] scores5 = new double[NUM_TESTS];

            
    // Method to set student's name
    public void setName(int studentNumber, String name)
    {
        names[studentNumber-1] = name;
    }
	 
    // Method sets student scores
	 
    public void setScores(int studentNumber, double[] scores)
    {
	switch(studentNumber)
	    {
	        case 1:copyArray(scores1,scores); break;
	        case 2:copyArray(scores2,scores); break;
	        case 3:copyArray(scores3,scores); break;
	        case 4:copyArray(scores4,scores); break;
	        case 5:copyArray(scores5,scores); break;
	        default:break;
	    }
    }
	 
    // Returns the student's name
	 
    public String getName(int studentNumber)
    {
	return names[studentNumber-1];
    }

    // Returns student's average score
	 
    public double getAverage(int studentNumber)
    {
	double avg=0.0;
	switch(studentNumber)
	{
	    case 1:avg = calcAverage(scores1); break;
	    case 2:avg = calcAverage(scores2); break;
	    case 3:avg = calcAverage(scores3); break;
	    case 4:avg = calcAverage(scores4); break;
	    case 5:avg = calcAverage(scores5); break;
	    default:break;
	}
	return avg;
    }
	 
    // Returns the student's letter grade
	 
    public char getLetterGrade(int studentNumber)
    {
	char lettergrade;
	if(getAverage(studentNumber)>=90 && getAverage(studentNumber)<=100)
            lettergrade = 'A';
	else if(getAverage(studentNumber)>=80 && getAverage(studentNumber)<=89)
	    lettergrade = 'B';
	else if(getAverage(studentNumber)>=70 && getAverage(studentNumber)<=79)
	    lettergrade = 'C';
	else if(getAverage(studentNumber)>=60 && getAverage(studentNumber)<=69)
	    lettergrade = 'D';
	else
            lettergrade = 'F';
	return lettergrade;
	  
    }
	  
    // Calculates the student's average
	 
    private double calcAverage(double[] scores)
    {
	double sum=0;
	for(int i=0; i<scores.length; i++)
            sum+=scores[i];
	return sum/scores.length;
	 
    }
	 
    // Determines student's letter grade based on average score
	 
    public char LetterGrade(double average)
    {
	char lettergrade;
	if(average>=90 && average<=100)
	    lettergrade = 'A';
	else if(average>=80 && average<=89)
	    lettergrade = 'B';
	else if(average>=70 && average<=79)
	    lettergrade = 'C';
	else if(average>=60 && average<=69)
	    lettergrade = 'D';
	else
	lettergrade = 'F';
	return lettergrade;
    }

    // Array copy method
    private void copyArray(double[] to, double[] from)
    {
	System.arraycopy(from, 0, to, 0, from.length);
    }
	
    
}

This here is the error I got:

run:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
	at Package1.GradeBookDemo.readFile(GradeBookDemo.java:64)
	at Package1.GradeBookDemo.main(GradeBookDemo.java:29)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

[Darryl Burke]

Alzecha Maris wrote:This here is the error I got:

run:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
	at Package1.GradeBookDemo.readFile(GradeBookDemo.java:64)
	at Package1.GradeBookDemo.main(GradeBookDemo.java:29)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

That error originates from line 64 of GradeBookDemo.java in the readFile(...) method.

Your GradeBookDemo.java posted here has 56 lines.

For someone to be able to help you, you need to post real code.

edit: corrected typo

[Alzecha Maris]

I apologize for that, I omitted the upper parts of the code because it contains my personal information. I forgot that would mess up the line numbering. Line 64 translates to 47 in the code I posted. I'll edit that into the OP.

[Campbell Ritchie]

I have altered the line numbers. You can find out how to do it here.

If you are getting that exception, it means you are trying to put a 5th value into a 4‑element array.
Remember a 4‑element array has index numbers 0…3.