Lucene 3.4.0 core API

Apache Lucene is a high-performance, full-featured text search engine library.


org.apache.lucene Top-level package.
org.apache.lucene.analysis API and code to convert text into indexable/searchable tokens.
org.apache.lucene.analysis.standard The org.apache.lucene.analysis.standard package contains three fast grammar-based tokenizers constructed with JFlex:
org.apache.lucene.collation CollationKeyFilter converts each token into its binary CollationKey using the provided Collator, and then encode the CollationKey as a String using IndexableBinaryStringTools, to allow it to be stored as an index term.
org.apache.lucene.document The logical representation of a Document for indexing and searching.
org.apache.lucene.index Code to maintain and access indices.
org.apache.lucene.messages For Native Language Support (NLS), system of software internationalization.
org.apache.lucene.queryParser A simple query parser implemented with JavaCC. Code to search indices.
Programmatic control over documents scores.
The payloads package provides Query mechanisms for finding and using payloads. The calculus of spans. Binary i/o API, used for all index data.
org.apache.lucene.util Some utility classes.
org.apache.lucene.util.fst Finite state transducers


Apache Lucene is a high-performance, full-featured text search engine library. Here's a simple example how to use Lucene for indexing and searching (using JUnit to check if the results are what we expect):

    Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);

    // Store the index in memory:
    Directory directory = new RAMDirectory();
    // To store an index on disk, use this instead:
    //Directory directory ="/tmp/testindex");
    IndexWriter iwriter = new IndexWriter(directory, analyzer, true,
                                          new IndexWriter.MaxFieldLength(25000));
    Document doc = new Document();
    String text = "This is the text to be indexed.";
    doc.add(new Field("fieldname", text, Field.Store.YES,
    // Now search the index:
    IndexSearcher isearcher = new IndexSearcher(directory, true); // read-only=true
    // Parse a simple query that searches for "text":
    QueryParser parser = new QueryParser("fieldname", analyzer);
    Query query = parser.parse("text");
    ScoreDoc[] hits =, null, 1000).scoreDocs;
    assertEquals(1, hits.length);
    // Iterate through the results:
    for (int i = 0; i < hits.length; i++) {
      Document hitDoc = isearcher.doc(hits[i].doc);
      assertEquals("This is the text to be indexed.", hitDoc.get("fieldname"));

The Lucene API is divided into several packages:

To use Lucene, an application should:
  1. Create Documents by adding Fields;
  2. Create an IndexWriter and add documents to it with addDocument();
  3. Call QueryParser.parse() to build a query from a string; and
  4. Create an IndexSearcher and pass the query to its search() method.
Some simple examples of code which does this are: To demonstrate these, try something like:
> java -cp lucene.jar:lucene-demo.jar:lucene-analyzers-common.jar org.apache.lucene.demo.IndexFiles
  [ ... ]

> java -cp lucene.jar:lucene-demo.jar:lucene-analyzers-common.jar org.apache.lucene.demo.SearchFiles
Query: chowder
Searching for: chowder
34 total matching documents
  [ ... thirty-four documents contain the word "chowder" ... ]

Query: "clam chowder" AND Manhattan
Searching for: +"clam chowder" +manhattan
2 total matching documents
  [ ... two documents contain the phrase "clam chowder" and the word "manhattan" ... ]
    [ Note: "+" and "-" are canonical, but "AND", "OR" and "NOT" may be used. ]

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