Book Image

Lucene 4 Cookbook

By : Edwood Ng, Vineeth Mohan
Book Image

Lucene 4 Cookbook

By: Edwood Ng, Vineeth Mohan

Overview of this book

Table of Contents (16 chapters)
Lucene 4 Cookbook
About the Authors
About the Reviewers


Before we start a search, we need to obtain an IndexSearcher to help us facilitate the querying of an index. IndexSearcher provides a number of search methods for querying data and returning TopDocs as results. TopDocs represents hits from a search and contains an array of ScoreDoc where it contains DocId and the score of each matching document. Note that TopDocs contains DocId and does not actually contain any document content. Document content retrieval will have to be relied on IndexReader or FieldCache. An IndexSearcher requires an IndexReader as an input to its constructor to initialize.

How to do it...

Let's look at a simple code snippet to see how IndexSearcher is set up:

Directory directory = File("/data/index"));
DirectoryReader directoryReader =;
IndexSearcher indexSearcher = new IndexSearcher(directoryReader);

How it works...

First, we set up a Directory so that we can pass it onto a DirectoryReader, which is basically...