How can I sort a Map according to the parameters of its values? [duplicate]

Answer 1

Map.Entry.comparingByValue() cannot serve as the comparator.

This is a comparator for Stream sorted(Comparator comparator):

Stream>> sortedStream = index.entrySet().stream()
        .sorted(new Comparator>>() {
    @Override
    public int compare(Entry> o1, Entry> o2) {
        return o1.getValue().size()-o2.getValue().size();
    }
});