org.apache.lucene.analysis.core
Class LetterTokenizer

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.Tokenizer
              org.apache.lucene.analysis.util.CharTokenizer
                  org.apache.lucene.analysis.core.LetterTokenizer

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

ArabicLetterTokenizer, LowerCaseTokenizer

public class LetterTokenizer
extends CharTokenizer

A LetterTokenizer is a tokenizer that divides text at non-letters. That's to say, it defines tokens as maximal strings of adjacent letters, as defined by java.lang.Character.isLetter() predicate.

Note: this does a decent job for most European languages, but does a terrible job for some Asian languages, where words are not separated by spaces.

You must specify the required Version compatibility when creating LetterTokenizer:

• As of 3.1, CharTokenizer uses an int based API to normalize and detect token characters. See CharTokenizer.isTokenChar(int) and CharTokenizer.normalize(int) for details.

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.Tokenizer

input

Constructor Summary

LetterTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader in)
Construct a new LetterTokenizer using a given AttributeSource.AttributeFactory.

LetterTokenizer(Version matchVersion, AttributeSource source, Reader in)
Construct a new LetterTokenizer using a given AttributeSource.

LetterTokenizer(Version matchVersion, Reader in)
Construct a new LetterTokenizer.

Method Summary

protected boolean

isTokenChar(int c) Collects only characters which satisfy Character.isLetter(int).

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

end, incrementToken, normalize, reset

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

close, correctOffset, setReader

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

LetterTokenizer

public LetterTokenizer(Version matchVersion,
                       Reader in)

Construct a new LetterTokenizer.

Parameters:

matchVersion - Lucene version to match See above

in - the input to split up into tokens

LetterTokenizer

public LetterTokenizer(Version matchVersion,
                       AttributeSource source,
                       Reader in)

Construct a new LetterTokenizer using a given AttributeSource.

Parameters:

matchVersion - Lucene version to match See above

source - the attribute source to use for this Tokenizer

in - the input to split up into tokens

LetterTokenizer

public LetterTokenizer(Version matchVersion,
                       AttributeSource.AttributeFactory factory,
                       Reader in)

Construct a new LetterTokenizer using a given AttributeSource.AttributeFactory.

Parameters:

matchVersion - Lucene version to match See above

factory - the attribute factory to use for this Tokenizer

in - the input to split up into tokens

Method Detail

isTokenChar

protected boolean isTokenChar(int c)

Collects only characters which satisfy Character.isLetter(int).

Specified by:

isTokenChar in class CharTokenizer