sort map groupingBy counting

Question

Is there way to sort map by value inside this collector without creation a new stream? Now it prints: AAS : 5 ABA : 195 ABC : 12 ABE : 52. Desired: ABA : 195 ABE : 52 ... getTrigraphStream(path) returns: HOW THE TRA GRI ONC GRI ONC INS WHE INS WHE

 public Map<String, Long> getTrigraphStatisticsMapAlphabet(String path) {
    return getTrigraphStream(path)
       .collect(groupingByConcurrent(Function.identity(),
           ConcurrentSkipListMap::new, counting()));
    }

Answer 1

Is there way to sort map by value inside this collector without creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

1. You'll need to invoke the stream() method after grouping and sort by value then collect to a map.
2. use collectingAndThen with a finishing function to do the sorting and then collect to map.

i.e.

return getTrigraphStream(path)
       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),
                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.