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Lucene example source code file (BooleanClause.java)

This example Lucene source code file (BooleanClause.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

booleanclause, booleanclause, must, must_not, occur, occur, override, override, query, should, string, string

The Lucene BooleanClause.java source code

package org.apache.lucene.search;

 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

/** A clause in a BooleanQuery. */
public class BooleanClause implements java.io.Serializable {
  /** Specifies how clauses are to occur in matching documents. */
  public static enum Occur {

    /** Use this operator for clauses that <i>must appear in the matching documents. */
    MUST     { @Override public String toString() { return "+"; } },

    /** Use this operator for clauses that <i>should appear in the 
     * matching documents. For a BooleanQuery with no <code>MUST 
     * clauses one or more <code>SHOULD clauses must match a document 
     * for the BooleanQuery to match.
     * @see BooleanQuery#setMinimumNumberShouldMatch
    SHOULD   { @Override public String toString() { return "";  } },

    /** Use this operator for clauses that <i>must not appear in the matching documents.
     * Note that it is not possible to search for queries that only consist
     * of a <code>MUST_NOT clause. */
    MUST_NOT { @Override public String toString() { return "-"; } };


  /** The query whose matching documents are combined by the boolean query.
  private Query query;

  private Occur occur;

  /** Constructs a BooleanClause.
  public BooleanClause(Query query, Occur occur) {
    this.query = query;
    this.occur = occur;

  public Occur getOccur() {
    return occur;

  public void setOccur(Occur occur) {
    this.occur = occur;


  public Query getQuery() {
    return query;

  public void setQuery(Query query) {
    this.query = query;
  public boolean isProhibited() {
    return Occur.MUST_NOT == occur;

  public boolean isRequired() {
    return Occur.MUST == occur;

  /** Returns true if <code>o is equal to this. */
  public boolean equals(Object o) {
    if (o == null || !(o instanceof BooleanClause))
      return false;
    BooleanClause other = (BooleanClause)o;
    return this.query.equals(other.query)
      && this.occur == other.occur;

  /** Returns a hash code value for this object.*/
  public int hashCode() {
    return query.hashCode() ^ (Occur.MUST == occur?1:0) ^ (Occur.MUST_NOT == occur?2:0);

  public String toString() {
    return occur.toString() + query.toString();

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene BooleanClause.java source code file:

my book on functional programming


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