How to sort a HashMap with key,value pair from an ArrayList in Java

Question

Hi i have a ArrayList of HashMap and i need the HashMap to be sorted by its key,Value.

ArrayList<HashMap> newList = new ArrayList();

loop start:

HashMap hashData = new HashMap();

hashData.put("name", "string-studentname");
hashData.put("mark", "int-studentmark");

newList.add(hashData);

loop end:

I need the newList to be sorted by the key-mark.

How do i get it?

Your list contains only one element. And that element is a hashmap with one name and one mark, because you overwrote them for each new student. Did you mean to create multiple hashmaps? — khelwood
– khelwood, Commented Apr 26, 2021 at 14:29

Thomas Jungblut · Accepted Answer · 2021-04-26 14:50:04Z

1

If you have multiple entries in your ArrayList and the key is the same, you can just sort via:

newList.sort(Comparator.comparingInt(o -> o.get("mark")));

Assuming you're typing the map properly:

HashMap<String, Integer> hashData = new HashMap<>();
hashData.put("mark", 1);

answered Apr 26, 2021 at 14:50

Thomas Jungblut

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