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.

Field Summary

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

input

Constructor Summary

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

StopFilter(TokenStream input, Set stopWords, boolean ignoreCase)
Construct a token stream filtering the given input.

StopFilter(TokenStream input, String[] stopWords)
Construct a token stream filtering the given input.

StopFilter(TokenStream in, String[] stopWords, boolean ignoreCase)
Constructs a filter which removes words from the input TokenStream that are named in the array of words.

Method Summary

static Set	makeStopSet(String[] stopWords) Builds a Set from an array of stop words, appropriate for passing into the StopFilter constructor.
static Set	makeStopSet(String[] stopWords, boolean ignoreCase)
Token	next() Returns the next input Token whose termText() is not a stop word.

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

close

Methods inherited from class java.lang.Object

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

Constructor Detail

StopFilter

public StopFilter(TokenStream input,
                  String[] stopWords)

Construct a token stream filtering the given input.

StopFilter

public StopFilter(TokenStream in,
                  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,
                  Set stopWords,
                  boolean ignoreCase)

Construct a token stream filtering the given input.

Parameters:

input -

stopWords - The set of Stop Words, as Strings. If ignoreCase is true, all strings should be lower cased

ignoreCase - -Ignore case when stopping. The stopWords set must be setup to contain only lower case words

StopFilter

public StopFilter(TokenStream in,
                  Set stopWords)

Constructs a filter which removes words from the input TokenStream that are named in the Set. It is crucial that an efficient Set implementation is used for maximum performance.

See Also:

makeStopSet(java.lang.String[])

Method Detail

makeStopSet

public static final Set makeStopSet(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 Set makeStopSet(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()
                 throws IOException

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

Specified by:

next in class TokenStream

Throws:

IOException