Set an item

You can set an item at an index with .set

import java.util.ArrayList;

void main() {
    ArrayList<String> names = new ArrayList<>();
    names.add("John Wick");

    names.set(0, "Baba Yaga");

    System.out.println(names);
    System.out.println(names.get(0));
}

If the index you provide is out of bounds, you will get an IndexOutOfBoundsException.

import java.util.ArrayList;

void main() {
    ArrayList<String> names = new ArrayList<>();
    names.add("John Wick");

    names.set(15, "Baba Yaga");
}