Class PorterStemFilter

  extended by org.apache.lucene.util.AttributeSource
      extended by org.apache.lucene.analysis.TokenStream
          extended by org.apache.lucene.analysis.TokenFilter
              extended by org.apache.lucene.analysis.en.PorterStemFilter
All Implemented Interfaces:

public final class PorterStemFilter
extends TokenFilter

Transforms the token stream as per the Porter stemming algorithm. Note: the input to the stemming filter must already be in lower case, so you will need to use LowerCaseFilter or LowerCaseTokenizer farther down the Tokenizer chain in order for this to work properly!

To use this filter with other analyzers, you'll want to write an Analyzer class that sets up the TokenStream chain as you want it. To use this with LowerCaseTokenizer, for example, you'd write an analyzer like this:

    class MyAnalyzer extends Analyzer {
      protected TokenStreamComponents createComponents(String fieldName, Reader reader) {
        Tokenizer source = new LowerCaseTokenizer(version, reader);
        return new TokenStreamComponents(source, new PorterStemFilter(source));

Note: This filter is aware of the KeywordAttribute. To prevent certain terms from being passed to the stemmer KeywordAttribute.isKeyword() should be set to true in a previous TokenStream.

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
Constructor Summary
PorterStemFilter(TokenStream in)
Method Summary
 boolean incrementToken()
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, reset
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


public PorterStemFilter(TokenStream in)
Method Detail


public final boolean incrementToken()
                             throws IOException
Specified by:
incrementToken in class TokenStream

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