CODEWITHSUNDEEP
javalistsorting
Marie
Marie

Reputation: 21

Java - Sort list of list LocalTime

I would like to sort a List<List<LocalTime>> with stream().

This is what the List looks like:

[[21:29, 22:29], [16:29, 17:29]]

and I would like the list to be like this

[[16:29, 17:29], [21:29, 22:29]]

Upvotes: 1

Views: 408

Answers (1)

Arvind Kumar Avinash
Arvind Kumar Avinash

Reputation: 79085

You can define a comparator as described in this answer and perform the sorting.

Demo:

import java.time.LocalTime;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.stream.IntStream;

public class Main {

    public static void main(String args[]) {
        List<List<LocalTime>> list = 
            new ArrayList<>(List.of(
                    new ArrayList<>(List.of(LocalTime.of(21, 29), (LocalTime.of(22, 29)))),
                    new ArrayList<>(List.of(LocalTime.of(16, 29), (LocalTime.of(17, 29))))
            ));

        Comparator<List<LocalTime>> comparator = 
            (list1, list2) -> 
                            IntStream.range(0, list1.size())
                                     .map(i -> list1.get(i).compareTo(list2.get(i)))
                                     .filter(value -> value != 0)
                                     .findFirst()
                                     .orElse(0);
        
        list.sort(comparator);

        System.out.println(list);
    }
}

Output:

[[16:29, 17:29], [21:29, 22:29]]

Upvotes: 1

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