org.apache.lucene.analysis

Class StopFilter

java.lang.Object

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.StopFilter

public final class StopFilter
extends TokenFilter

Removes stop words from a token stream.

Constructor Summary

Constructors

Constructor and Description
StopFilter(TokenStream in, java.util.Set stopWords) Constructs a filter which removes words from the input TokenStream that are named in the Set.
StopFilter(TokenStream input, java.util.Set stopWords, boolean ignoreCase) Construct a token stream filtering the given input.
StopFilter(TokenStream input, java.lang.String[] stopWords) Construct a token stream filtering the given input.
StopFilter(TokenStream in, java.lang.String[] stopWords, boolean ignoreCase) Constructs a filter which removes words from the input TokenStream that are named in the array of words.

Method Summary

Modifier and Type	Method and Description
boolean	getEnablePositionIncrements()
static boolean	getEnablePositionIncrementsDefault()
static java.util.Set	makeStopSet(java.lang.String[] stopWords) Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor.
static java.util.Set	makeStopSet(java.lang.String[] stopWords, boolean ignoreCase)
Token	next(Token result) Returns the next input Token whose termText() is not a stop word.
void	setEnablePositionIncrements(boolean enable) Set to true to make this StopFilter enable position increments to result tokens.
static void	setEnablePositionIncrementsDefault(boolean defaultValue) Set the default position increments behavior of every StopFilter created from now on.

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

close

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

next, reset

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StopFilter

public StopFilter(TokenStream input,
                  java.lang.String[] stopWords)

Construct a token stream filtering the given input.

StopFilter

public StopFilter(TokenStream in,
                  java.lang.String[] stopWords,
                  boolean ignoreCase)

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

StopFilter

public StopFilter(TokenStream input,
                  java.util.Set stopWords,
                  boolean ignoreCase)

Construct a token stream filtering the given input. If stopWords is an instance of CharArraySet (true if makeStopSet() was used to construct the set) it will be directly used and ignoreCase will be ignored since CharArraySet directly controls case sensitivity.

If stopWords is not an instance of CharArraySet, a new CharArraySet will be constructed and ignoreCase will be used to specify the case sensitivity of that set.

Parameters:

input -

stopWords - The set of Stop Words.

ignoreCase - -Ignore case when stopping.

StopFilter

public StopFilter(TokenStream in,
                  java.util.Set stopWords)

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

See Also:

makeStopSet(java.lang.String[])

Method Detail

makeStopSet

public static final java.util.Set makeStopSet(java.lang.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.

See Also:

passing false to ignoreCase

makeStopSet

public static final java.util.Set makeStopSet(java.lang.String[] stopWords,
                                              boolean ignoreCase)

Parameters:

stopWords -

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

Returns:

a Set containing the words

next

public final Token next(Token result)
                 throws java.io.IOException

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

Overrides:

next in class TokenStream

Parameters:

result - a Token that may or may not be used to return

Returns:

next token in the stream or null if end-of-stream was hit

Throws:

java.io.IOException

getEnablePositionIncrementsDefault

public static boolean getEnablePositionIncrementsDefault()

See Also:

setEnablePositionIncrementsDefault(boolean).

setEnablePositionIncrementsDefault

public static void setEnablePositionIncrementsDefault(boolean defaultValue)

Set the default position increments behavior of every StopFilter created from now on.

Note: behavior of a single StopFilter instance can be modified with setEnablePositionIncrements(boolean). This static method allows control over behavior of classes using StopFilters internally, for example StandardAnalyzer.

Default : false.

See Also:

setEnablePositionIncrements(boolean).

getEnablePositionIncrements

public boolean getEnablePositionIncrements()

See Also:

setEnablePositionIncrements(boolean).

setEnablePositionIncrements

public void setEnablePositionIncrements(boolean enable)

Set to true to make this StopFilter enable position increments to result tokens.

When set, when a token is stopped (omitted), the position increment of the following token is incremented.

Default: see setEnablePositionIncrementsDefault(boolean).