Add a single element at the specified index

I'd love to exercise the CRUD principle in ArrayList in java
I started today by exercising the add method however I get error
when I add the methode add in static main methode I get error that the add methode should be static
and when I put it static I get error by the arraylist and scanner as Strange element even wenn I add those the the static add methode After excuting the ide I get error " Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 2, Size: 0" could someone explain me why is so

package com.company;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    Scanner scanner = new Scanner(System.in);
    List<String> arrayList1 = new ArrayList<>();

    public static void main(String[] args) {
	
        Scanner scanner = new Scanner(System.in);
        List<String> arrayList1 = new ArrayList<>();

        add();
        System.out.println(arrayList1);
    }

    public static void add(){
        Scanner scanner = new Scanner(System.in);
        List<String> arrayList1 = new ArrayList<>();

        int index=scanner.nextInt();
        String element=scanner.next();
        arrayList1.add(index,element);

    }
}

To put it simply: You can't just add an element at a certain index (that isn't the 0th) in an uninitialized list. When you call your add function the array list is empty, which is why you're getting an IndexOutOfBoundsException error.

When you create a list, it is initially empty. You can't add an element to index 2 if there is no item at index 0. The ArrayList class does not create elements out of nowhere for the positions 0 and 1.

You can always add an element to the end of a list, or to the beginning of a list, even if the list is empty. These are always safe:

arrayList1.add(0, element); // Add to beginning of the list
arrayList1.add(element);    // Add to end of the list

Your program has some duplicate and unused variables. For example, scanner and arrayList1 don't have to re-declared and initialized in every method - in fact, doing it will lead to bugs further down the line. You can make the class-level variables static and then you can use them in all methods:

class Main {
    static Scanner scanner = new Scanner(System.in);
    static List<String> arrayList1 = new ArrayList<>();

    public static void main(String[] args) {
        add();
        System.out.println(arrayList1);
    }

    public static void add() {
        int index = scanner.nextInt();
        String element = scanner.next();
        arrayList1.add(index, element);
    }
}

This is not the best way to program in Java, as you will learn when your studies bring you to object oriented concepts but for a beginner this is good enough