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Trouble with an ArrayIndexOutOfBoundsException in Java

I'm having a little trouble with a java array and was hoping for some assistance. I am trying to make a program that will take information from 3 files - one that includes student last names, one that includes their gpa, and one that includes their student number. However, when I run the program I get the afore mentioned ArrayIndexOutOfBoundsException as:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3
at Final.loadArrays(Final.java:40)
at Final.main(Final.java:25)


I have made sure the files contain data and no additional spaces / etc. Please find my code below, and thanks for your assistance.

import java.util.Scanner;
import java.io.FileNotFoundException;
import java.io.FileReader;
import javax.swing.JOptionPane;

public class studentinfo


public static void main(String args) throws FileNotFoundException


final int MAX_SIZE = 3;
String names = new String[MAX_SIZE];
double gpa = new double[MAX_SIZE];
int studentNumber = new int[MAX_SIZE];

loadArrays(names, gpa, studentNumber);


public static void loadArrays(String names, double gpa, int studentNumber) throws FileNotFoundException


Scanner namesInFile = new Scanner(new FileReader ("names.txt"));
Scanner gpaInFile = new Scanner(new FileReader ("gpa.txt"));
Scanner studentNumberInFile = new Scanner(new FileReader ("studentNumber.txt"));

int i = 0;
//loop for loading names array
while(namesInFile.hasNext())


names[i] = namesInFile.next();
i++;



i = 0;
//loop for loading gpa array
while (gpaInFile.hasNext())

gpa[i] = gpaInFile.nextDouble();
i++;


i = 0;
//loop for loading student number array
while (studentNumberInFile.hasNext())

studentNumber[i] = studentNumberInFile.nextInt();
i++;




namesInFile.close();
gpaInFile.close();
studentNumberInFile.close();


for(i = 0; i < names.length ; i++)
System.out.println(names[i]);

for(i = 0; i < gpa.length ; i++)
System.out.println(gpa[i]);

for(i = 0; i < studentNumber.length ; i++)
System.out.println(studentNumber[i]);
String message = "";
for(i = 0; i < gpa.length ; i++)
message += studentNumber[i]+" "+names[i]+" "+gpa[i]+"n";

JOptionPane.showMessageDialog(null, message);



Can you post the input files as well?
– Sweeper
2 hours ago

I took your code and ran it in Eclipse with no issues - with that being said I can tell you most likely have a couple of issues: 1) The file that you are pointing at has more than 3 entries 2) You have some unknown characters in your files (maybe an additional line break?) add system out's to your code and that will tell you where it is breaking :)
– Bob
2 hours ago

Possible duplicate of What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?
– Jacob B.
2 hours ago

Thank you so much Bob, that answered my question. I was mistaken in thinking that the MAX_SIZE had to do with elements in the array, not the number of entries in the file. I appreciate it!
– BiscuitWrangler
13 mins ago

2 Answers
2

final int MAX_SIZE = 3;//Are you sure that the number of contents in your documents is less more than MAX_SIZE?

3 is your file number not the number of students in your files. Do not use array since you don't know the actual number, use List instead.

3

List

import java.util.ArrayList;


Change array to array list.

ArrayList<String> names = new ArrayList<>();
ArrayList<Double> gpa = new ArrayList<>();
ArrayList<Integer> studentNumber = new ArrayList<>();


Use add and get(index).

add

get(index)

names.add(namesInFile.next());


And

System.out.println(names.get(i));


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