Creating and writing documents to an index

This recipe shows you how to index a document. In fact, here we are putting together all that we learned so far from the previous recipes. Let's see how it is done.

How to do it...

The following code sample shows you an example of adding a simple document to an index:

public class LuceneTest {
  public static void main(String[] args) throws IOException {
    Analyzer analyzer = new WhitespaceAnalyzer();
    Directory directory = new RAMDirectory();
    IndexWriterConfig config = new IndexWriterConfig(Version.LATEST, analyzer);
      IndexWriter indexWriter = new IndexWriter(directory,
        config);
      Document doc = new Document();
      String text = "Lucene is an Information Retrieval library written in Java";
      doc.add(new TextField("fieldname", text, Field.Store.YES));
      indexWriter.addDocument(doc);
      indexWriter.close();
    }
}

Tip

Downloading the example code

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How it works…

Note that the preceding code snippet combined all the sample codes we learned so far. It first initializes an analyzer, directory, IndexWriterConfig, and IndexWriter. Once the IndexWriter is obtained, a new Document is created with a custom TextField. The Document is then added to IndexWriter. Also, note that we call indexWriter.close() at the end. calling this method, will commit all changes and close the index.

The IndexWriter class exposes an addDocument(doc) method that allows you to add documents to an index. IndexWriter will write to an index specified by directory.