Sort Object HashMap (not by key)

Question

So I have several objects in a HashMap: private HashMap <String,Object> hmap;

what I want to do is sort this objects through a variable of the objects (a double). How should I do this? I think I'm required to use comparators, but I don't know exactly how to work with them. Should I send the objects to an array?

http://docs.oracle.com/javase/tutorial/collections/index.html — JB Nizet, May 24 '12 at 18:12
possible duplicate of [How to sort a Map on the values in Java?](http://stackoverflow.com/questions/109383/how-to-sort-a-mapkey-value-on-the-values-in-java) — Guido, May 24 '12 at 18:13

Hakan Serce · Accepted Answer · 2012-05-24T18:48:42.767

2

I guess you will need to do sorting in a separate List. You will need something like below:

List<Object> values = new ArrayList<Object>();
values.addAll(hmap.values());
Collections.sort( values, new Comparator<Object>(){ 
 public int compare(Object o1,
                   Object o2){
    //do specific comparison here
 });

edited May 24 '12 at 18:48

answered May 24 '12 at 18:20

Hakan Serce

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notice that the 'compare' function must return positive values when o1 > o2, negative value when o1 < o2, and zero when o1 == o2 – kajacx May 24 '12 at 18:42
List is this really exists in Java? – pbaris May 24 '12 at 18:48

Sort Object HashMap (not by key)

1 Answers1