Java SortedSet add all

Question

The following code creates a sorted set that sorts by its values rather thank keys. vertexRank is an object responsible for getting the value. Everything works well except the code: vertexCentralities.addAll(vMap.entrySet()); What happens is that only the first entry from vMap is added to vertexCentralities rather than all entries.

1. How can I get all entries from vMap into vertexCentralities?

   SortedSet<Map.Entry<String, Double>> vertexCentralities = 
           new TreeSet<Map.Entry<String, Double>>(
           new Comparator<Map.Entry<String, Double>>()
           {
              @Override
              public int compare(Map.Entry<String, Double> e1, Map.Entry<String, Double> e2)
              {
                  return e2.getValue().compareTo(e1.getValue());
              }
            });
   SortedMap<String, Double> vMap = new TreeMap<String, Double>();
   double curRank = 0;
   for(String vStr: g.getVertices())
   {
       curRank = vertexRank.getVertexScore(vStr);
       vMap.put(vStr, curRank);
   }
   
   vertexCentralities.addAll(vMap.entrySet());
   

Answer 1

I tried running:

public static final void main(final String[] args) {
    final String[] vStrs = new String[] { "A", "Z", "E", "R", "T", "Y" }; // init

    final SortedSet<Map.Entry<String, Double>> vertexCentralities = new TreeSet<Map.Entry<String, Double>>(new Comparator<Map.Entry<String, Double>>() {
        @Override
        public int compare(final Map.Entry<String, Double> e1, final Map.Entry<String, Double> e2) {
            return e2.getValue().compareTo(e1.getValue());
        }
    });
    final SortedMap<String, Double> vMap = new TreeMap<String, Double>();
    double curRank = 0;
    for (final String vStr : vStrs) {
        curRank = new Random().nextDouble() * 100.0; // replacing
                                                        // vertexRank.getVertexScore(vStr);
                                                        // for testing
        vMap.put(vStr, curRank);
    }
    vertexCentralities.addAll(vMap.entrySet());

    for (final Map.Entry<String, Double> entry : vertexCentralities) {
        System.out.println(entry.getKey() + ": " + entry.getValue());
    }

}

and the output was sorted by value:

A: 70.50008784770233
Z: 55.48252329485239
E: 37.31308600830347
Y: 32.534528844628255
T: 16.544965680467794
R: 12.258316023552872

Maybe your problem comes from somewhere else... like g.getVertices() or vertexRank.getVertexScore(vStr)

EDIT: I tried with duplicates values for the String and for the double:

final String[] vStrs = new String[] { "A", "Z", "E", "R", "T", "Y", "A" };
curRank = new Random().nextInt(3);

and it looks like no duplicates are allowed. Is this your problem?

EDIT: Found a solution if you want to allow multiple entry with the same Double: Replace your SortedSet vertexCentralities's comparator condition to:

final int bValue = e2.getValue().compareTo(e1.getValue());
return bValue != 0 ? bValue : e2.getKey().compareTo(e1.getKey());

Answer 2

An alternative solution could be to use SimpleEntry<K, V> (inner public static class of java.util.AbstractMap) and avoid the SortedMap:

final SortedSet<Map.Entry<String, Double>> vertexCentralities = new TreeSet<Map.Entry<String, Double>>(new Comparator<Map.Entry<String, Double>>() {
    @Override
    public int compare(final Map.Entry<String, Double> e1, final Map.Entry<String, Double> e2) {
        final int bValue = e2.getValue().compareTo(e1.getValue());
        return bValue != 0 ? bValue : e2.getKey().compareTo(e1.getKey());
    }
});
double curRank = 0;
for (final String vStr : g.getVertices()) {
    curRank = vertexRank.getVertexScore(vStr);
    vertexCentralities.add(new SimpleEntry<String, Double>(vStr, curRank));
}

You should be able to have duplicate Key or Value but not both.