This codes were taken from a website,where i modified the directory, that is working fine but when considering the concurrency, this codes have problems

			1.The codes for indexing
			

			

				

				public MakeIndex() throws Exception {
				

				// create a Lucene index IndexWriter instance:
				

				

				IndexWriter indexWriter ;
				

				try{
				

				indexWriter= new IndexWriter("C:\eclipse-311\tryMadhan\MedicalRecordIndexRecords\index3", new StandardAnalyzer(), false);
				

				}
				

				catch(Exception e){
				

				

				indexWriter=new IndexWriter("C:\eclipse-311\tryMadhan\MedicalRecordIndexRecords\index3", new StandardAnalyzer(), true);
				

				}
				

				File dir = new File(EXAMPLE_DOCUMENT_PATH);
				

				AllTextFilesFilter filter = new AllTextFilesFilter();
				

				String[] ss = dir.list(filter);
				

				if (ss == null || ss.length == 0) return;
				

				for (int i = 0; i
				< ss.length; i++) {
				

				String fullPath = EXAMPLE_DOCUMENT_PATH + "/" + ss[i];
				

				// add the text in this file to the lucene index:
				

				Document document = new Document();
				

				// note: the second argument to Field.Text can be the string of text to index (in which
				

				// case it is stored in the index) or a file reader (in which case the text is read
				

				// and indexed, but not stored in the index)
				

				document.add(Field.Text("text", new FileReader(fullPath)));
				

				document.add(Field.UnIndexed("filepath", fullPath));
				

				indexWriter.addDocument(document);
				

				System.out.println("Wrote file " + fullPath + " to index.");
				

				}
				

				indexWriter.optimize();
				

				indexWriter.close();
				

				}
				

				

				class AllTextFilesFilter implements FilenameFilter {
				

				public AllTextFilesFilter() {
				

				}
				

				final public boolean accept(File dir, String name) {
				

				if (name.equals(".DS_Store")) return false; // Mac OS X only - safe on other platforms
				

				File ff = new File(dir.toString() + "/" + name);
				

				if (ff.isDirectory()) return false;
				

				return true;
				

				}
				

				}
				

				

			
		

2. The part for searching

			

			Analyzer analyzer = new StandardAnalyzer();
			

			

			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
			

			

			System.out.print("Search query (enter a blank query to stop) : ");
			

			

			

			while (true) {
			

			System.out.print("Search query (enter a blank query to stop) : ");
			

			String line = in.readLine();
			

			

			if (line == null || line.length()
			< 1)  break;
			

			

			Query query = QueryParser.parse(line, "text", analyzer);
			

			System.out.println("Searching for: " + query.toString("text"));
			

			Searcher searcher = new IndexSearcher("C:\eclipse-311\tryMadhan\MedicalRecordIndexRecords\index3");
			

			Hits hits = searcher.search(query);
			

			

			System.out.println("Number of matching documents = " + hits.length());
			

			

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

			Document doc = hits.doc(i);
			

			System.out.println("File: " + doc.get("filepath") + ", score: " + hits.score(i));
			

			}
			

			searcher.close();
			

			}
			

			

			}
			

			

		

problems are as follows

1.When i create 3 threads all indexing,there is a exception being thrown

3.When i create 4 threads with 2 indexing and 2 searching, the searching shows 0 where it suppose to show a correct result as 3 matching documents.

Hope to hear from any1 with a solution.I don't have the lucene in action book so i am unable to refer the book and i am also new to all this concurrency issue and lucene.Hope to hear a helping hand to solve my trouble.Thank You