Empty Query - More Like This (Lucene) - lucene

Question

I'm new at Java and Lucene.
I'm trying a simple MLT test, but I'm not getting any results.
import java.io.File;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.Version;
import org.apache.lucene.index.DirectoryReader;
import java.io.IOException;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.queries.mlt.MoreLikeThis;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.SimpleFSDirectory;
public class HelloLucene {
public static void main(String[] args) throws IOException, ParseException {
StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_40);
String indexPath = "C:/Users/Name/Desktop/Lucene";
Directory index = new SimpleFSDirectory(new File(indexPath));
IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_40, analyzer);
IndexWriter w = new IndexWriter(index, config);
addDoc(w, "Lucene in Action", "193398817");
addDoc(w, "Lucene for Dummies", "55320055Z");
addDoc(w, "Managing Gigabytes", "55063554A");
addDoc(w, "The Art of Computer Science", "9900333X");
w.close();
IndexReader reader = DirectoryReader.open(index);
System.out.println("Reader has " + reader.numDocs() + " docs on it.");
MoreLikeThis mlt = new MoreLikeThis(reader);
mlt.setMinTermFreq(1);
mlt.setMinDocFreq(1);
Query query = mlt.like(0); //doc ID
IndexSearcher searcher = new IndexSearcher(reader);
TopDocs topDocs = searcher.search(query,5);
System.out.println("Found " + topDocs.totalHits + " hits.");
for (ScoreDoc scoreDoc : topDocs.scoreDocs) {
Document doc = searcher.doc(scoreDoc.doc);
System.out.println(scoreDoc.doc + ". " + doc.get("isbn") + "\t" + doc.get("title"));
}
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);
}
}
And this is what I get:
Reader has 4 docs on it.
Found 0 hits.
I tried using Luke to check the Doc's ID and there is nothing wrong apparently.
I even did some tests there, I dont know whats wrong :(
Did a lot of searching on the web, someone said something about the settings as MinTermFreq and MinDocFreq, I tried 1 and 0, but got nothing.
Does anyone have an idea?
Thanks in advance!
[SOLVED] Edited:
its working now!
I just had to add this:
mlt.setAnalyzer(analyzer);
mlt.setFieldNames(new String[] {"title"});

Answer 1

its working now!
I just had to add this:
mlt.setAnalyzer(analyzer);
mlt.setFieldNames(new String[] {"title"});