org.apache.lucene.analysis.ja
Class JapaneseKatakanaStemFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.TokenFilter
              org.apache.lucene.analysis.ja.JapaneseKatakanaStemFilter

All Implemented Interfaces:

Closeable

public final class JapaneseKatakanaStemFilter
extends org.apache.lucene.analysis.TokenFilter

Convert a katakana word to a normalized form by stemming KATAKANA-HIRAGANA PROLONGED SOUND MARK (U+30FC) which exists at the last of the string. In general, most of Japanese full-text search engine uses more complicated method which needs dictionaries. I think they are better than this filter in quality, but they needs a well-tuned dictionary. In contract, this filter is simple and maintenance-free.

Note: This filter don't supports hankaku katakana characters, so you must convert them before using this filter. And this filter support only pre-composed characters.

To prevent terms from being stemmed use an instance of KeywordMarkerFilter or a custom TokenFilter that sets the KeywordAttribute before this TokenStream.

Nested Class Summary

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

org.apache.lucene.util.AttributeSource.AttributeFactory, org.apache.lucene.util.AttributeSource.State

Field Summary

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

input

Constructor Summary

JapaneseKatakanaStemFilter(org.apache.lucene.analysis.TokenStream in)

Method Summary

boolean

incrementToken() Returns the next input Token, after being stemmed

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, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

JapaneseKatakanaStemFilter

public JapaneseKatakanaStemFilter(org.apache.lucene.analysis.TokenStream in)

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Returns the next input Token, after being stemmed

Specified by:

incrementToken in class org.apache.lucene.analysis.TokenStream

Throws:

IOException