adding documents to an existing index in lucene

Question

hello all, I would like to ask of how to add new documents to an existing lucene index. in the source code below, I just change the paramater of IndexWriter into false.

IndexWriter indexWriter = new IndexWriter(
            FSDirectory.open(indexDir),
            new SimpleAnalyzer(),
            false,
            IndexWriter.MaxFieldLength.LIMITED);

because false means that the index will still be open and not close. also to add new document I should use

indexWriter.addDocument(doc)

but my question is how exactly can I add new documents to an existing lucene index. I am a bit loss in finding out where to put a new path directory containing new Documents in lucene class so that lucene can index those new documents and add it into existing indexes. any help would be appreciated though. thanks.

import org.apache.lucene.analysis.SimpleAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.store.FSDirectory;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

public class testlucene1 {
public static void main(String[] args) throws Exception {
    File indexDir = new File("C:/Users/Raden/Documents/lucene/LuceneHibernate/adi");
    File dataDir = new File("C:/Users/Raden/Documents/lucene/LuceneHibernate/adi");
    String suffix = "txt";
    testlucene1 indexer = new testlucene1();
    int numIndex = indexer.index(indexDir, dataDir, suffix);
    System.out.println("Total files indexed " + numIndex);
}

private int index(File indexDir, File dataDir, String suffix) throws Exception {
    IndexWriter indexWriter = new IndexWriter(
            FSDirectory.open(indexDir),
            new SimpleAnalyzer(),
            false,
            IndexWriter.MaxFieldLength.LIMITED);
    indexWriter.setUseCompoundFile(false);
    indexDirectory(indexWriter, dataDir, suffix);
    int numIndexed = indexWriter.maxDoc();
    indexWriter.optimize();
    indexWriter.close();
    return numIndexed;
}

   private void indexDirectory(IndexWriter indexWriter, File dataDir, String suffix)    throws IOException {
    File[] files = dataDir.listFiles();
    for (int i = 0; i < files.length; i++) {
        File f = files[i];
        if (f.isDirectory()) {
            indexDirectory(indexWriter, f, suffix);
        } else {
            indexFileWithIndexWriter(indexWriter, f, suffix);
        }
    }
}

private void indexFileWithIndexWriter(IndexWriter indexWriter, File f, String suffix) throws IOException {
    if (f.isHidden() || f.isDirectory() || !f.canRead() || !f.exists()) {
        return;
    }
    if (suffix != null && !f.getName().endsWith(suffix)) {
        return;
    }
    System.out.println("Indexing file " + f.getCanonicalPath());
    Document doc = new Document();
    doc.add(new Field("contents", new FileReader(f)));
    doc.add(new Field("filename", f.getCanonicalPath(), Field.Store.YES,  Field.Index.ANALYZED));
    indexWriter.addDocument(doc);
}
} 

Answer 1

When you instantiate a new IndexWriter, you will not create a new index (unless you explicitly tell lucene to force a new one). So your code will work, regardless of whether the index already exists.

Answer 2

also to add new document I should use .... but my question is how exactly can I add new documents to an existing lucene index

can you please clarify what you mean? you know how to add documents to an index, as you stated, but then you ask how to... add new documents?