It's my first time to use Lucene and I'm using MultiFieldQueryParser for doing an advance search on our site. When I run the site (using Netbeans 5.5's built-in Tomcat server) and do a sample search, it produces results. However, the next searches I make (including doing the same search I did the first time) doesn't work. Netbeans only says that the error is "null". The error occurs when it runs Query query = mparser.parse(queries, fields, occurs, getAnalyzer()); Please help. Here's my code:

			

			public Vector advSearch(String[] fields, String[] queries, BooleanClause.Occur[] occurs)
			

			

			{
			

			

			  int i;
			

			

			  Vector results = null;
			

			

			

			

			  try
			

			

			  {
			

			

			    Searcher searcher = new IndexSearcher(Constants.INDEXDIR);
			

			

			    MultiFieldQueryParser mparser = new MultiFieldQueryParser(fields, getAnalyzer());
			

			

			    Query query = mparser.parse(queries, fields, occurs, getAnalyzer());
			

			

			

			

			    Hits hits = searcher.search(query);
			

			

			

			

			    for(i = 0; i
			< hits.length(); i++)
			

			

			    {
			

			

			      if(results == null)
			

			

			        results = new Vector();
			

			

			

			

			      Document doc = hits.doc(i);
			

			

			      Text t = this.getDocumentDetails(doc.get("url"), hits.score(i));
			

			

			

			

			      results.add(t);
			

			

			    }
			

			

			

			

			    searcher.close();
			

			

			  }
			

			

			

			

			  catch(Exception e)
			

			

			  {
			

			

			    System.out.println("generalError: " + e.getMessage());
			

			

			  }
			

			

			

			

			  return results;
			

			

			}