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I have a list:

List<A> aList

where A:
public class A{
private Long id;

private LocalDate created;

private AStatus status; //enum

...other fields
}

public enum AStatus{
    NEW, SEND, WAITING, CANCELLED
}

How to sort my List FIRST by created in DESC order and then I want to have elements with the status NEW as first (and then elements with other AStatus), like:

1 10.12.2020 NEW
2 10.12.2020 SEND
3 10.12.2020 CANCELLED
4 08.12.2020 NEW
5 08.12.2020 NEW
Mureinik
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Matley
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  • IF we have eg. 3 rows with the same date then status NEW has to be always at the top of the list (as FIRST, before other AStatus for the same date) – Matley Dec 05 '20 at 18:49

1 Answers1

1

You could create a custom Comparator that sorts with by created and then by a boolean of whether status == AStatus.NEW (remember - false comes before true when sorting booleans):

List<A> aList = // something...
    
// I assume these getters exist
aList.sort(Comparator.comparing(A::getCreated).reversed() 
                     .thenComparing(a -> a.getStatus() != AStatus.NEW)
);
Mureinik
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  • one more thing - created has to be in DESC order... Ahhh... I have to use reverse() method probably – Matley Dec 05 '20 at 18:55
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    @Matley didn't notice that requirement, my bad. You can add a `reversed()` call there to reverse the order - see my edited answer – Mureinik Dec 05 '20 at 19:00
  • Another cool way to do it if this is the natural way these objects of type A will be compared is to add the Comparable interface to your class and keep the logic inside the class instead of outside. Then you will just use list.sort(); – Veselin Davidov Dec 05 '20 at 19:02