Why this takes error?(the for loop)

Question

import java.util.Scanner;

public class Program
{
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String text = scanner.nextLine();
char[] arr = text.toCharArray();

for(int i = arr.length ; i>=0 ; i--){
System.out.println(arr[i]);
}
}
}

Answer 1

juanestragon 10

Should be (arr.length - 1)

Because index starts from 0 so ['a', 'b', 'c'] will have 0, 1, 2 index now think in reverse 2, 1, 0

Answer 2

Suppose you have an array on length 3. Then the highest index will be 2, not 3. However, your current loop would start with the non-existant index 3.