sorting - Java - get top 15 from HashMap by rule

Question

I would like to ask for help. Let's say I have HashMap with key-value like this:

String1 0.99
String2 0.98
String3 0.97
String4 0.98
String5 0.5
String6 0.4
String7 0.3
etc.

And I would like to save to array the top 15 entries by this formula: Math.abs(value - 0.5).

The counted values (by the formula) for this data would be:

String1 0.49
String2 0.48
String3 0.47
String4 0.48
String5 0
String6 0.1
String7 0.2

The values sorted

String1 0.49
String4 0.48
String2 0.48
String3 0.47
String7 0.2
String6 0.1
String5 0

And now I would like to have array, where index would be the order and value the original value, like this:

array[0] = 0.99
array[1] = 0.98
array[2] = 0.98
array[3] = 0.97
array[4] = 0.3
array[5] = 0.4
array[6] = 0.5 

Thanks everyone for help

Any help would be appreciated. Thank You

Answer 1

You can use Java 8 stream API:

List<Double> result = map.values().stream()
        .map(value -> Math.abs(value - 0.5))
        .sorted()
        .limit(15)
        .collect(toList());