Sort ArrayList of custom Objects by property

I read about sorting ArrayLists using a Comparator but in all of the examples people used compareTo which according to some research is a method for Strings.

I wanted to sort an ArrayList of custom objects by one of their properties: a Date object
(getStartDay()). Normally I compare them by item1.getStartDate().before(item2.getStartDate()) so I was wondering whether I could write something like:

public class CustomComparator {
    public boolean compare(Object object1, Object object2) {
        return object1.getStartDate().before(object2.getStartDate());
    }
}

public class RandomName {
    ...
    Collections.sort(Database.arrayList, new CustomComparator);
    ...
}