How can I fix exception in thread "main" java.lang.arrayindexoutofboundsexception

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Java

package quera;

import java.util.Scanner;
public class Quera {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("How many students do you have?");
        int n = scanner.nextInt();

        for (int i = 0 ; i < n ;i++){
        System.out.println("Enter their names and the number of courses in order :");
        String student = scanner.next();
        int course = scanner.nextInt();
        System.out.println("Enter her\\his scores : " );
        
        int[][] scores = new  int[n][];
             
            for(int x =0 ; x < course ; x++){
                 scores[n][course] =  scanner.nextInt();     
            }
        }
    }
}

What I have tried:

I m trying to store all scores in a 2D jagged array (I need to use those scores out of the loop to calculate the average of every student and find the highest one.)

Posted 22-Oct-21 9:09am

MELIKA Kazemi

Updated 22-Oct-21 22:43pm

Richard MacCutchan

v3

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MELIKA Kazemi 22-Oct-21 15:14pm

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3
at quera.Quera.main(Quera.java:23)

Patrice T 22-Oct-21 16:16pm

Use Improve question to update your question.
So that everyone can pay attention to this information.

1 solution

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Richard MacCutchan · Answer 1 · 2021-10-22T22:43:00

Solution 1

This is a repeat fo your previous question at How can I store students scores outside the loop in a 2D jagged array? ([^]. Go back there and read my suggestions again. You must allocate the main array before you start the loop, based on the number of students:

Java

System.out.println("How many students do you have?");
int n = scanner.nextInt();
int[][] scores = new int[n][];

Then when you start each new student's entries inside the main loop, you need to allocate the student array as I suggested in the other question.

Posted 22-Oct-21 22:43pm

Richard MacCutchan

Comments

MELIKA Kazemi 23-Oct-21 20:39pm

I'm working on it and trying for days but I can't solve it.
Could you plz do me a favor and put those arrays inside the code?I tried everything but I still get exceptions

Richard MacCutchan 24-Oct-21 3:34am

You need to stop coding and think carefully about the steps you need to take to get this working.
1. As I mention above capture the student count.
2. Now start a loop that goes from 0 to n (the number of students).
3. Ask for the student name and number of courses.
4. Create a new array at scores[i] of to hold the marks for each course. The length of the array should be the number of courses.
5. Now start a new (inner) loop to capture the marks.
6. Get the marks for the next course and store it in scores[i][j]
At then end of the inner loop it will start the next iteration to capture the next student's details.
When all students have been processed you should have a jagged array containing all the student marks.