org.apache.lucene.analysis.core

Class LowerCaseTokenizer

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

org.apache.lucene.analysis.core.LowerCaseTokenizer

All Implemented Interfaces:

Closeable

public final class LowerCaseTokenizer
extends LetterTokenizer

LowerCaseTokenizer performs the function of LetterTokenizer and LowerCaseFilter together. It divides text at non-letters and converts them to lower case. While it is functionally equivalent to the combination of LetterTokenizer and LowerCaseFilter, there is a performance advantage to doing the two tasks at once, hence this (redundant) implementation.

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 LowerCaseTokenizer:

• 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

Constructors

Constructor and Description
LowerCaseTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader in) Construct a new LowerCaseTokenizer using a given AttributeSource.AttributeFactory.
LowerCaseTokenizer(Version matchVersion, Reader in) Construct a new LowerCaseTokenizer.

Method Summary

Methods

Modifier and Type	Method and Description
protected int	normalize(int c) Converts char to lower case Character.toLowerCase(int).

Methods inherited from class org.apache.lucene.analysis.core.LetterTokenizer

isTokenChar

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

end, incrementToken, 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

LowerCaseTokenizer

public LowerCaseTokenizer(Version matchVersion,
                  Reader in)

Construct a new LowerCaseTokenizer.

Parameters:

matchVersion - Lucene version to match See above

in - the input to split up into tokens

LowerCaseTokenizer

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

Construct a new LowerCaseTokenizer 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

normalize

protected int normalize(int c)

Converts char to lower case Character.toLowerCase(int).

Overrides:

normalize in class CharTokenizer