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

I was facing same issue and I tried all the solutions but not able to fix the problem, Then I tried following way and finally I am able to fix my problem.

In above example my studlist was already sorted but still its generating map in any order that was main question.

Map> studlistGrouped =
    studlist.stream().collect(Collectors.groupingBy(w -> w.stud_location));
**studlistGrouped = new TreeMap>(studlistGrouped);**

So using this above solution it sorted all the keys in Map. Our goal to get result into Map only then why people try to converting it into list?