Package org.apache.lucene.analysis.de

Class GermanNormalizationFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.de.GermanNormalizationFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Unwrappable<TokenStream>

public final class GermanNormalizationFilter
extends TokenFilter

Normalizes German characters according to the heuristics of the German2 snowball algorithm. It allows for the fact that ä, ö and ü are sometimes written as ae, oe and ue.

• 'ß' is replaced by 'ss'
• 'ä', 'ö', 'ü' are replaced by 'a', 'o', 'u', respectively.
• 'ae' and 'oe' are replaced by 'a', and 'o', respectively.
• 'ue' is replaced by 'u', when not following a vowel or q.

This is useful if you want this normalization without using the German2 stemmer, or perhaps no stemming at all.

Nested Class Summary

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

AttributeSource.State

Field Summary

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
GermanNormalizationFilter(TokenStream input)

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()

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

close, end, reset, unwrap

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString

Methods inherited from class java.lang.Object

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

Constructor Details

GermanNormalizationFilter

public GermanNormalizationFilter(TokenStream input)

Method Details

incrementToken

public boolean incrementToken()
                       throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException