Get minvalue of a Map(Key,Double)

Question

Is there a method (maybe with Google Collections) to obtain the min value of a Map(Key, Double)?

In the traditional way, I would have to sort the map according to the values, and take the first/last one.

Answer 1

You can use the standard Collections#min() for this.

Map<String, Double> map = new HashMap<String, Double>(); map.put("1.1", 1.1); map.put("0.1", 0.1); map.put("2.1", 2.1);  Double min = Collections.min(map.values()); System.out.println(min); // 0.1 

Update: since you need the key as well, well, I don't see ways in Collections or Google Collections2 API since a Map is not a Collection. The Maps#filterEntries() is also not really useful, since you only know the actual result at end of iteration.

Most straightforward solution would then be this:

Entry<String, Double> min = null; for (Entry<String, Double> entry : map.entrySet()) {     if (min == null || min.getValue() > entry.getValue()) {         min = entry;     } }  System.out.println(min.getKey()); // 0.1 

(nullcheck on min left aside)

Answer 2

You still can use Collections.min with a custom Comparator to get the Map.Entry with the lower value:

Map<String, Double> map = new HashMap<String, Double>(); map.put("1.1", 1.1); map.put("0.1", 0.1); map.put("2.1", 2.1); Entry<String, Double> min = Collections.min(map.entrySet(), new Comparator<Entry<String, Double>>() {     public int compare(Entry<String, Double> entry1, Entry<String, Double> entry2) {         return entry1.getValue().compareTo(entry2.getValue());     } }); System.out.printf("%s: %f", min.getKey(), min.getValue()); // 0.1: 0.100000 

With Java 8:

Entry<String, Double> min = Collections.min(map.entrySet(),                                        Comparator.comparing(Entry::getValue));