Java 8, Lambda: Sorting within grouped Lists and merging all groups to a list

Question

Based on the following answer: https://stackoverflow.com/a/30202075/8760211

How to sort each group by stud_id and then return a List with all Students as result of the g

Answer 1

You don't need to group by location, as the input and output have same datatype. You can just chain multiple Comparators and sort the input.

List groupedAndSorted = studlist.stream()
       .sorted(Comparator.comparing(Student::getStudLocation)
                .thenComparing(Comparator.comparing(Student::getStudId)))
                .thenComparing(Comparator.comparing(Student::getStudName)))
       .collect(Collectors.toList());

As an offtopic, I would seggest that you change you data structure to use Lombok to auto-generate getters/setters/constructors https://projectlombok.org/features/Data . You should also use a more generic naming conversion, i.e. remove the "stud_" prefix of attributes.

import lombok.Data;
@Data
class Student {
    String id;
    String name;
    String location;
}