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

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

Field Summary

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

input

Constructor Summary

Constructors

Constructor and 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

Methods

Modifier and Type	Method and Description
protected boolean	accept() Returns the next input Token whose term() is not a stop word.
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.
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.

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

getEnablePositionIncrements, incrementToken, reset, setEnablePositionIncrements

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

close, end

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

Methods inherited from class java.lang.Object

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

Constructor Detail

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 Detail

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

accept

protected boolean accept()

Returns the next input Token whose term() is not a stop word.

Specified by:

accept in class FilteringTokenFilter