Package org.apache.lucene.analysis.core

Class StopFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.util.FilteringTokenFilter

org.apache.lucene.analysis.core.StopFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class StopFilter
extends FilteringTokenFilter

Removes stop words from a token stream.

You must specify the required Version compatibility when creating StopFilter:

• As of 3.1, StopFilter correctly handles Unicode 4.0 supplementary characters in stopwords and position increments are preserved

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Constructor Summary

Constructors

Constructor	Description
StopFilter(Version matchVersion, TokenStream in, CharArraySet stopWords)	Constructs a filter which removes words from the input TokenStream that are named in the Set.

Method Summary

Modifier and Type	Method	Description
static CharArraySet	makeStopSet(Version matchVersion, String... stopWords)	Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor.
static CharArraySet	makeStopSet(Version matchVersion, String[] stopWords, boolean ignoreCase)	Creates a stopword set from the given stopword array.
static CharArraySet	makeStopSet(Version matchVersion, List<?> stopWords)	Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor.
static CharArraySet	makeStopSet(Version matchVersion, List<?> stopWords, boolean ignoreCase)	Creates a stopword set from the given stopword list.

Methods inherited from class org.apache.lucene.analysis.util.FilteringTokenFilter

end, getEnablePositionIncrements, incrementToken, reset, setEnablePositionIncrements

Methods inherited from class org.apache.lucene.analysis.TokenFilter

close

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

StopFilter

public StopFilter(Version matchVersion,
 TokenStream in,
 CharArraySet stopWords)

Constructs a filter which removes words from the input TokenStream that are named in the Set.

Parameters:

matchVersion - Lucene version to enable correct Unicode 4.0 behavior in the stop set if Version > 3.0. See above for details.

in - Input stream

stopWords - A CharArraySet representing the stopwords.

See Also:

• makeStopSet(Version, java.lang.String...)

Method Details

makeStopSet

public static CharArraySet makeStopSet(Version matchVersion,
 String... stopWords)

Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor. This permits this stopWords construction to be cached once when an Analyzer is constructed.

Parameters:

matchVersion - Lucene version to enable correct Unicode 4.0 behavior in the returned set if Version > 3.0

stopWords - An array of stopwords

See Also:

• passing false to ignoreCase

makeStopSet

public static CharArraySet makeStopSet(Version matchVersion,
 List<?> stopWords)

Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor. This permits this stopWords construction to be cached once when an Analyzer is constructed.

Parameters:

matchVersion - Lucene version to enable correct Unicode 4.0 behavior in the returned set if Version > 3.0

stopWords - A List of Strings or char[] or any other toString()-able list representing the stopwords

Returns:

A Set (CharArraySet) containing the words

See Also:

• passing false to ignoreCase

makeStopSet

public static CharArraySet makeStopSet(Version matchVersion,
 String[] stopWords,
 boolean ignoreCase)

Creates a stopword set from the given stopword array.

Parameters:

matchVersion - Lucene version to enable correct Unicode 4.0 behavior in the returned set if Version > 3.0

stopWords - An array of stopwords

ignoreCase - If true, all words are lower cased first.

Returns:

a Set containing the words

makeStopSet

public static CharArraySet makeStopSet(Version matchVersion,
 List<?> stopWords,
 boolean ignoreCase)

Creates a stopword set from the given stopword list.

Parameters:

matchVersion - Lucene version to enable correct Unicode 4.0 behavior in the returned set if Version > 3.0

stopWords - A List of Strings or char[] or any other toString()-able list representing the stopwords

ignoreCase - if true, all words are lower cased first

Returns:

A Set (CharArraySet) containing the words