org.apache.lucene.search

Class Query

java.lang.Object

org.apache.lucene.search.Query

Direct Known Subclasses:

BlendedTermQuery, BooleanQuery, BoostQuery, ConstantScoreQuery, DisjunctionMaxQuery, FieldValueQuery, GraphQuery, MatchAllDocsQuery, MatchNoDocsQuery, MultiPhraseQuery, MultiTermQuery, NGramPhraseQuery, PhraseQuery, PointInSetQuery, PointRangeQuery, SpanQuery, SynonymQuery, TermQuery

public abstract class Query
extends Object

The abstract base class for queries.

Instantiable subclasses are:

• TermQuery
• BooleanQuery
• WildcardQuery
• PhraseQuery
• PrefixQuery
• MultiPhraseQuery
• FuzzyQuery
• RegexpQuery
• TermRangeQuery
• PointRangeQuery
• ConstantScoreQuery
• DisjunctionMaxQuery
• MatchAllDocsQuery

See also the family of Span Queries and additional queries available in the Queries module

Constructor Summary

Constructors

Constructor and Description
Query()

Method Summary

Modifier and Type	Method and Description
protected int	classHash() Provides a constant integer for a given class, derived from the name of the class.
Weight	createWeight(IndexSearcher searcher, boolean needsScores) Expert: Constructs an appropriate Weight implementation for this query.
abstract boolean	equals(Object obj) Override and implement query instance equivalence properly in a subclass.
abstract int	hashCode() Override and implement query hash code properly in a subclass.
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
protected boolean	sameClassAs(Object other) Utility method to check whether other is not null and is exactly of the same class as this object's class.
String	toString() Prints a query to a string.
abstract String	toString(String field) Prints a query to a string, with field assumed to be the default field and omitted.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Query

public Query()

Method Detail

toString

public abstract String toString(String field)

Prints a query to a string, with field assumed to be the default field and omitted.

toString

public final String toString()

Prints a query to a string.

Overrides:

toString in class Object

createWeight

public Weight createWeight(IndexSearcher searcher,
                           boolean needsScores)
                    throws IOException

Expert: Constructs an appropriate Weight implementation for this query.

Only implemented by primitive queries, which re-write to themselves.

Parameters:

needsScores - True if document scores (Scorer.score()) or match frequencies (Scorer.freq()) are needed.

Throws:

IOException

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

Throws:

IOException

equals

public abstract boolean equals(Object obj)

Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly. Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.

Overrides:

equals in class Object

See Also:

sameClassAs(Object), classHash()

hashCode

public abstract int hashCode()

Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.

Overrides:

hashCode in class Object

See Also:

equals(Object)

sameClassAs

protected final boolean sameClassAs(Object other)

Utility method to check whether other is not null and is exactly of the same class as this object's class. When this method is used in an implementation of equals(Object), consider using classHash() in the implementation of hashCode() to differentiate different class

classHash

protected final int classHash()

Provides a constant integer for a given class, derived from the name of the class. The rationale for not using just Object.hashCode() is that classes may be assigned different hash codes for each execution and we want hashes to be possibly consistent to facilitate debugging.