How to get a category in Java WordNet Library

Question

I have extracted the synsets for each word. Now I want to get the domain or category for each synset meaning for example that if I have the word light I want to get physics i.e. the domain(s) of the synset.

Now supposing I have the synset sense this should be done by:

Pointer[] domain = sense.getPointers(PointerType.CATEGORY);

By doing this I get always domain" empty error. Where am I wrong?

Furthermore, is there a way to get a string indicating the domain?

Answer 1

Ok, nobody seems interested in it but I'll post my working solution.

 //'WordnetPOS' is an instance of the class POS defined in JWNL. It indicates the part of        
//speech tag. token
JWNL.initialize(new FileInputStream("path/file_properties.xml"));
Dictionary wordnet = Dictionary.getInstance();
IndexWord token = wordnet.lookupIndexWord(WordnetPos, word); //word is a string
Synset[] senses = token.getSenses();
String Dom = new String();

for (int i = 0; i < senses.length; i++) {
   String domSet = new String();
   try {

   //CATEGORY is the pointer type of the synset containing the domains

   Pointer[] pointerArr = senses[i].getPointers(PointerType.CATEGORY);
   for (Pointer pointer : pointerArr) {
       Synset syn = pointer.getTargetSynset();
       Word[] words = syn.getWords();
       for (Word word : words) {
           domaSet = domaSet + word.getLemma().trim().toLowerCase() + " ";
       }
   }
   catch (NullPointerException e) {
   }
   Dom = Dom + domSet;
}

Answer 2

Thank you so much for posting your solution. It is a good example and it becomes very useful for me. However I thought I can also share this with the rest of the community.

WordNet has a hypernym / hyponym hierarchy. For instance, when you look up goalkeeper:

Synset('physical_entity.n.01') 
Synset('causal_agent.n.01') 
Synset('person.n.01')
Synset('contestant.n.01')
Synset('athlete.n.01')
Synset('soccer_player.n.01')
Synset('goalkeeper.n.01')

However, using WordNet Domains project could be a different approach. Going back to the goalkeeper example, it can return [sport->football; sport->hockey] or [football;hockey] or just 'football'

For more information please feel free to check out Get WordNet's domain name for the specified word