how sort in java8 list of lists of object by multiple properties

Question

I know this is not a new question but I want to sort CSV file by Column preferred in java8.

The Data-structure of CSV is List<List<CsvEntity> I need to sort first by one field of the CsvEntity then by other (not must) example by: firstName then by lastName.

class CsvEntity{
   private String firstName
   private String lastName
   private String address
}

Following this - How to sort data in a CSV file using a particular field in Java?

What modifications do I need to make for supporting sort on multiple keys in Java8?

What do you want to sort? Elements in the outermost list? Or `CsvEntity` elements in nested lists? — ernest_k, Feb 08 '19 at 10:28
This will help :https://stackoverflow.com/questions/35761864/java-sort-list-of-lists — soorapadman, Feb 08 '19 at 10:30
See : https://stackoverflow.com/questions/45769908/how-to-sort-the-name-along-with-age-in-java/54396193#54396193 — Vishwa Ratna, Feb 08 '19 at 10:41

Schidu Luca · Accepted Answer · 2019-02-08T11:37:45.290

2

Just use comparator, an example of sorting by firstName then by lastName

list.forEach(l -> l.sort(Comparator.comparing(CsvEntity::getFirstName)
                               .thenComparing(CsvEntity::getLastName)));

Of course you have to have getters for your fields to use method reference

edited Feb 08 '19 at 11:37

answered Feb 08 '19 at 10:27

Schidu Luca

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score 0 · Answer 2 · answered Feb 08 '19 at 10:47

        final Function<CsvEntity, String> byfirstName = CsvEntity -> CsvEntity.getfirstname();
        final Function<CsvEntity, String> bylastname = CsvEntity -> CsvEntity.getlastname();
        final Function<CsvEntity, String> byaddress = CsvEntity -> CsvEntity.getaddress(); 
        System.out.println("Sorted in ascending order by Firstname and Lastname: ");
        List<CsvEntity> sortedlist =   CsvEntity.stream()
            .sorted(Comparator.comparing(byfirstName).thenComparing(bylastname))
            .collect(Collectors.toList());

how sort in java8 list of lists of object by multiple properties

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