Package org.apache.lucene.analysis.icu

Class ICUCollationAttributeFactory

java.lang.Object
org.apache.lucene.util.AttributeFactory
org.apache.lucene.util.AttributeFactory.StaticImplementationAttributeFactory<ICUCollatedTermAttributeImpl>
org.apache.lucene.analysis.icu.ICUCollationAttributeFactory
public class ICUCollationAttributeFactory extends org.apache.lucene.util.AttributeFactory.StaticImplementationAttributeFactory<ICUCollatedTermAttributeImpl>
Converts each token into its CollationKey, and then encodes bytes as an index term.

WARNING: Make sure you use exactly the same Collator at index and query time -- CollationKeys are only comparable when produced by the same Collator. RuleBasedCollators are independently versioned, so it is safe to search against stored CollationKeys if the following are exactly the same (best practice is to store this information with the index and check that they remain the same at query time):

  1. Collator version - see Collator.getVersion()
  2. The collation strength used - see Collator.setStrength(int)

CollationKeys generated by ICU Collators are not compatible with those generated by java.text.Collators. Specifically, if you use ICUCollationAttributeFactory to generate index terms, do not use CollationAttributeFactory on the query side, or vice versa.

ICUCollationAttributeFactory is significantly faster and generates significantly shorter keys than CollationAttributeFactory. See http://site.icu-project.org/charts/collation-icu4j-sun for key generation timing and key length comparisons between ICU4J and java.text.Collator over several languages.

  • Nested Class Summary

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

    org.apache.lucene.util.AttributeFactory.StaticImplementationAttributeFactory<A extends org.apache.lucene.util.AttributeImpl>

  • Field Summary

    Fields inherited from class org.apache.lucene.util.AttributeFactory

    DEFAULT_ATTRIBUTE_FACTORY

  • Constructor Summary

    Constructors
    Constructor
    Description
    ICUCollationAttributeFactory(com.ibm.icu.text.Collator collator)
    Create an ICUCollationAttributeFactory, using TokenStream.DEFAULT_TOKEN_ATTRIBUTE_FACTORY as the factory for all other attributes.
    ICUCollationAttributeFactory(org.apache.lucene.util.AttributeFactory delegate, com.ibm.icu.text.Collator collator)
    Create an ICUCollationAttributeFactory, using the supplied Attribute Factory as the factory for all other attributes.

  • Method Summary

    Modifier and Type
    Method
    Description
    ICUCollatedTermAttributeImpl
    createInstance()
     

    Methods inherited from class org.apache.lucene.util.AttributeFactory.StaticImplementationAttributeFactory

    createAttributeInstance, equals, hashCode

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

    getStaticImplementation

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • ICUCollationAttributeFactory

      public ICUCollationAttributeFactory(com.ibm.icu.text.Collator collator)
      Create an ICUCollationAttributeFactory, using TokenStream.DEFAULT_TOKEN_ATTRIBUTE_FACTORY as the factory for all other attributes.
      Parameters:
      collator - CollationKey generator

    • ICUCollationAttributeFactory

      public ICUCollationAttributeFactory(org.apache.lucene.util.AttributeFactory delegate, com.ibm.icu.text.Collator collator)
      Create an ICUCollationAttributeFactory, using the supplied Attribute Factory as the factory for all other attributes.
      Parameters:
      delegate - Attribute Factory
      collator - CollationKey generator

  • Method Details