Lucene 4.0 in text search

Question

I'm using lucene 4.0 with java. I'm trying to search for a string inside a string. If we look at the lucene hello world example, I wish to find the text "lucene" inside the phrase "inLuceneAction". I want it to find me two matches in this case instead of one.

Any Idea on how to do it?

Thanks

public class HelloLucene {
 public static void main(String[] args) throws IOException, ParseException {
// 0. Specify the analyzer for tokenizing text.
//    The same analyzer should be used for indexing and searching
StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_40);

// 1. create the index
Directory index = new RAMDirectory();

IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_40, analyzer);

IndexWriter w = new IndexWriter(index, config);
addDoc(w, "inLuceneAction", "193398817");
addDoc(w, "Lucene for Dummies", "55320055Z");
addDoc(w, "Managing Gigabytes", "55063554A");
addDoc(w, "The Art of Computer Science", "9900333X");
w.close();

// 2. query
String querystr = args.length > 0 ? args[0] : "lucene";

// the "title" arg specifies the default field to use
// when no field is explicitly specified in the query.
Query q = new QueryParser(Version.LUCENE_40, "title", analyzer).parse(querystr);

// 3. search
int hitsPerPage = 10;
IndexReader reader = DirectoryReader.open(index);
IndexSearcher searcher = new IndexSearcher(reader);
TopScoreDocCollector collector = TopScoreDocCollector.create(hitsPerPage, true);
searcher.search(q, collector);
ScoreDoc[] hits = collector.topDocs().scoreDocs;

// 4. display results
System.out.println("Found " + hits.length + " hits.");
for(int i=0;i<hits.length;++i) {
  int docId = hits[i].doc;
  Document d = searcher.doc(docId);
  System.out.println((i + 1) + ". " + d.get("isbn") + "\t" + d.get("title"));
}
// reader can only be closed when there
// is no need to access the documents any more.
reader.close(); 
}
private static void addDoc(IndexWriter w, String title, String isbn) throws IOException {
Document doc = new Document();
doc.add(new TextField("title", title, Field.Store.YES));

// use a string field for isbn because we don't want it tokenized
doc.add(new StringField("isbn", isbn, Field.Store.YES));
w.addDocument(doc);
}
}

Answer 1

If you index the terms in the default way, meaning inLuceneAction is one term, Lucene won't be able to seek to this term given Lucene because it has a different prefix. Analyze this string so that it results in three indexed terms: in Lucene Action and then you'll have it fetched. You'll either find a ready-made analyzer for this or you'll have to write your own. Writing own analyzers is a bit out of scope for a single StackOverflow answer, but an excellent place to start is the package info at the bottom of the org.apache.lucene.analysis package Javadoc page.