Java 2D ArrayList and sorting

Question

I need to sort a shopping list by the aisle the item is located for example:
[Bread] [1]
[Milk] [2]
[Cereal] [3]

I am planning to do this with ArrayList and

Answer 1

I know the question was asked long ago but actually i had the same problem. If you dont know how many variables you would have on list but this is not a big number you could just implement comparator for every choose. eg

I have ArrayList> and want to sort it by column's and i know that the nested list consist of variable number of objects i can just implement comparator for every possible value:

public class SecondColumnComparator implements Comparator {

public static boolean isNumeric(String str) {
    try {
        Integer integer = Integer.parseInt(str);
    } catch (NumberFormatException nfe) {
        return false;
    }
    return true;
}

@Override
public int compare(Object o1, Object o2) {

    if (isNumeric(((ArrayList) o1).get(1))) {

        Integer firstInteger = Integer.parseInt(((ArrayList) o1).get(1));
        Integer secondInteger = Integer.parseInt(((ArrayList) o2).get(1));

        return firstInteger.compareTo(secondInteger);

    }
    if (((ArrayList