Lucene - BooleanQuery


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BooleanQuery is used to search documents which are a result of multiple queries using AND, OR or NOT operators.

Class Declaration

Following is the declaration for the org.apache.lucene.search.BooleanQuery class −

public class BooleanQuery
   extends Query
      implements Iterable<BooleanClause>

Fields

Following is the field for the BooleanQuery −

  • protected int minNrShouldMatch

Class Constructors

The following table shows the different class constructors −

S.No. Constructor & Description
1

BooleanQuery()

Constructs an empty Boolean query.

2

BooleanQuery(boolean disableCoord)

Constructs an empty Boolean query.

Class Methods

The following table shows the different class methods −

S.No. Method & Description
1

void add(BooleanClause clause)

Adds a clause to a Boolean query.

2

void add(Query query, BooleanClause.Occur occur)

Adds a clause to a boolean query.

3

List<BooleanClause> clauses()

Returns the list of clauses in this query.

4

Object clone()

Returns a clone of this query.

5

Weight createWeight(Searcher searcher)

Expert: Constructs an appropriate Weight implementation for this query.

6

boolean equals(Object o)

Returns true if object o is equal to this.

7

void extractTerms(Set terms)

Expert: Adds all terms occurring in this query to the terms set.

8

BooleanClause[] getClauses()

Returns the set of clauses in this query.

9

static int getMaxClauseCount()

Returns the maximum number of clauses permitted, 1024 by default.

10

int getMinimumNumberShouldMatch()

Gets the minimum number of the optional BooleanClauses which must be satisfied.

11

int hashCode()

Returns a hash code value for this object.

12

boolean isCoordDisabled()

Returns true if Similarity.coord(int,int) is disabled in scoring for this query instance.

13

Iterator<BooleanClause> iterator()

Returns an iterator on the clauses in this query.

14

Query rewrite(IndexReader reader)

Expert: Called to re-write queries into primitive queries.

15

static void setMaxClauseCount(int maxClauseCount)

Sets the maximum number of clauses permitted per BooleanQuery.

16

void setMinimumNumberShouldMatch(int min)

Specifies a minimum number of the optional BooleanClauses which must be satisfied.

17

String toString(String field)

Prints a user-readable version of this query.

Methods Inherited

This class inherits methods from the following classes −

  • org.apache.lucene.search.Query
  • java.lang.Object

Usage

private void searchUsingBooleanQuery(String searchQuery1,
   String searchQuery2)throws IOException, ParseException {
   searcher = new Searcher(indexDir);
   long startTime = System.currentTimeMillis();
   
   //create a term to search file name
   Term term1 = new Term(LuceneConstants.FILE_NAME, searchQuery1);
   //create the term query object
   Query query1 = new TermQuery(term1);

   Term term2 = new Term(LuceneConstants.FILE_NAME, searchQuery2);
   //create the term query object
   Query query2 = new PrefixQuery(term2);

   BooleanQuery query = new BooleanQuery();
   query.add(query1,BooleanClause.Occur.MUST_NOT);
   query.add(query2,BooleanClause.Occur.MUST);

   //do the search
   TopDocs hits = searcher.search(query);
   long endTime = System.currentTimeMillis();

   System.out.println(hits.totalHits +
      " documents found. Time :" + (endTime - startTime) + "ms");
   for(ScoreDoc scoreDoc : hits.scoreDocs) {
      Document doc = searcher.getDocument(scoreDoc);
      System.out.println("File: "+ doc.get(LuceneConstants.FILE_PATH));
   }
   searcher.close();
}

Example Application

Let us create a test Lucene application to test search using BooleanQuery.

Step Description
1

Create a project with a name LuceneFirstApplication under a package com.tutorialspoint.lucene as explained in the Lucene - First Application chapter. You can also use the project created in Lucene - First Application chapter as such for this chapter to understand the searching process.

2

Create LuceneConstants.java and Searcher.java as explained in the Lucene - First Application chapter. Keep the rest of the files unchanged.

3

Create LuceneTester.java as mentioned below.

4

Clean and Build the application to make sure the business logic is working as per the requirements.

LuceneConstants.java

This class is used to provide various constants to be used across the sample application.

package com.tutorialspoint.lucene;

public class LuceneConstants {
   public static final String CONTENTS = "contents";
   public static final String FILE_NAME = "filename";
   public static final String FILE_PATH = "filepath";
   public static final int MAX_SEARCH = 10;
}

Searcher.java

This class is used to read the indexes made on raw data and searches data using the Lucene library.

package com.tutorialspoint.lucene;

import java.io.File;
import java.io.IOException;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

public class Searcher {
	
   IndexSearcher indexSearcher;
   QueryParser queryParser;
   Query query;

   public Searcher(String indexDirectoryPath) throws IOException {
      Directory indexDirectory = 
         FSDirectory.open(new File(indexDirectoryPath));
      indexSearcher = new IndexSearcher(indexDirectory);
      queryParser = new QueryParser(Version.LUCENE_36,
         LuceneConstants.CONTENTS,
         new StandardAnalyzer(Version.LUCENE_36));
   }

   public TopDocs search( String searchQuery) 
      throws IOException, ParseException {
      query = queryParser.parse(searchQuery);
      return indexSearcher.search(query, LuceneConstants.MAX_SEARCH);
   }
   
   public TopDocs search(Query query) throws IOException, ParseException {
      return indexSearcher.search(query, LuceneConstants.MAX_SEARCH);
   }

   public Document getDocument(ScoreDoc scoreDoc) 
      throws CorruptIndexException, IOException {
     return indexSearcher.doc(scoreDoc.doc);	
   }

   public void close() throws IOException {
      indexSearcher.close();
   }
}

LuceneTester.java

This class is used to test the searching capability of the Lucene library.

package com.tutorialspoint.lucene;

import java.io.IOException;

import org.apache.lucene.document.Document;
import org.apache.lucene.index.Term;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.PrefixQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.TopDocs;

public class LuceneTester {
	
   String indexDir = "E:\\Lucene\\Index";
   String dataDir = "E:\\Lucene\\Data";
   Searcher searcher;

   public static void main(String[] args) {
      LuceneTester tester;
      try {
         tester = new LuceneTester();
         tester.searchUsingBooleanQuery("record1.txt","record1");
      } catch (IOException e) {
         e.printStackTrace();
      } catch (ParseException e) {
         e.printStackTrace();
      }
   }

   private void searchUsingBooleanQuery(String searchQuery1,
      String searchQuery2)throws IOException, ParseException {
      searcher = new Searcher(indexDir);
      long startTime = System.currentTimeMillis();
      
      //create a term to search file name
      Term term1 = new Term(LuceneConstants.FILE_NAME, searchQuery1);
      //create the term query object
      Query query1 = new TermQuery(term1);

      Term term2 = new Term(LuceneConstants.FILE_NAME, searchQuery2);
      //create the term query object
      Query query2 = new PrefixQuery(term2);

      BooleanQuery query = new BooleanQuery();
      query.add(query1,BooleanClause.Occur.MUST_NOT);
      query.add(query2,BooleanClause.Occur.MUST);

      //do the search
      TopDocs hits = searcher.search(query);
      long endTime = System.currentTimeMillis();

      System.out.println(hits.totalHits +
            " documents found. Time :" + (endTime - startTime) + "ms");
      for(ScoreDoc scoreDoc : hits.scoreDocs) {
         Document doc = searcher.getDocument(scoreDoc);
         System.out.println("File: "+ doc.get(LuceneConstants.FILE_PATH));
      }
      searcher.close();
   }
}

Data & Index Directory Creation

We have used 10 text files from record1.txt to record10.txt containing names and other details of the students and put them in the directory E:\Lucene\Data. Test Data. An index directory path should be created as E:\Lucene\Index. After running the indexing program during chapter Lucene - Indexing Process, you can see the list of index files created in that folder.

Running the Program

Once you are done with the creation of the source, the raw data, the data directory, the index directory and the indexes, you can proceed by compiling and running your program. To do this, keep the LuceneTester.Java file tab active and use either the Run option available in the Eclipse IDE or use Ctrl + F11 to compile and run your LuceneTester application. If everything is fine with your application, this will print the following message in Eclipse IDE's console −

1 documents found. Time :26ms
File: E:\Lucene\Data\record10.txt

lucene_query_programming.htm

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