Simplest way to iterate through a Multiset in the order of element frequency?

Question

Consider this example which prints out some device type stats. (\"DeviceType\" is an enum with a dozenish values.)

Multiset histogram = get         


        

Answer 1

An Implementation using ForwardingMultiSet :

(EntryComp from seanizer's answer)

enum EntryComp implements Comparator> {
    DESCENDING {
        @Override
        public int compare(final Entry a, final Entry b) {
            return Ints.compare(b.getCount(), a.getCount());
        }
    },
    ASCENDING {
        @Override
        public int compare(final Entry a, final Entry b) {
            return Ints.compare(a.getCount(), b.getCount());
        }
    },
}

public class FreqSortMultiSet extends ForwardingMultiset {
    Multiset delegate;
    EntryComp comp;

    public FreqSortMultiSet(Multiset delegate, boolean ascending) {
        this.delegate = delegate;
        if (ascending)
            this.comp = EntryComp.ASCENDING;
        else
            this.comp = EntryComp.DESCENDING;
    }

    @Override
    protected Multiset delegate() {
        return delegate;
    }

    @Override
    public Set> entrySet() {
        TreeSet> sortedEntrySet = new TreeSet>(comp);
        sortedEntrySet.addAll(delegate.entrySet());
        return sortedEntrySet;
    }

    @Override
    public Set elementSet() {
        Set sortedEntrySet = new LinkedHashSet();
        for (Entry en : entrySet())
            sortedEntrySet.add(en.getElement());
        return sortedEntrySet;
    }

    public static  FreqSortMultiSet create(boolean ascending) {
        return new FreqSortMultiSet(HashMultiset. create(), ascending);
    }

    /*
     * For Testing
     * public static void main(String[] args) {
        Multiset s = FreqSortMultiSet.create(false);
        s.add("Hello");
        s.add("Hello");
        s.setCount("World", 3);
        s.setCount("Bye", 5);
        System.out.println(s.entrySet());
    }*/

}