How to get the earliest date of a List in Java?

Question

I have an ArrayList which stores 0...4 Dates.

The amount of Dates in the list depends on a Business logic.

How can I get the earliest date of this list? Of course I can build iterative loops to finally retrieve the earliest date. But is there a 'cleaner'/ quicker way of doing this, especially when considering that this list can grow on a later perspective?

Answer 1

java.util.Date implements Comparable<Date>, so you can simply use:

Date minDate = Collections.min(listOfDates);

This relies on there being at least one element in the list. If the list might be empty (amongst many other approaches):

Optional<Date> minDate = listOfDates.stream().min(Comparator.naturalOrder());

Answer 2

SortedSet

Depending on your application you can think about using a SortedSet (like TreeSet). This allows you to change the collection and always receive the lowest element easily.

Adding elements to the collection is more expensive, though.

Answer 3

If you dont mind to change the insertion order then sort the list and get the elemeent at index 0