org.apache.lucene.analysis.icu

## Class ICUNormalizer2Filter

- java.lang.Object
- - org.apache.lucene.util.AttributeSource
  - - org.apache.lucene.analysis.TokenStream
    - - org.apache.lucene.analysis.TokenFilter
      - - org.apache.lucene.analysis.icu.ICUNormalizer2Filter

- All Implemented Interfaces:
    Closeable, AutoCloseable
  Direct Known Subclasses:
    ICUFoldingFilter

      public class ICUNormalizer2Filter
      extends TokenFilter

  Normalize token text with ICU's `Normalizer2`

  With this filter, you can normalize text in the following ways:

  - NFKC Normalization, Case Folding, and removing Ignorables (the default)
  - Using a standard Normalization mode (NFC, NFD, NFKC, NFKD)
  - Based on rules from a custom normalization mapping.

  If you use the defaults, this filter is a simple way to standardize Unicode text in a language-independent way for search:

  - The case folding that it does can be seen as a replacement for LowerCaseFilter: For example, it handles cases such as the Greek sigma, so that "Μάϊος" and "ΜΆΪΟΣ" will match correctly.
  - The normalization will standardizes different forms of the same character in Unicode. For example, CJK full-width numbers will be standardized to their ASCII forms.
  - Ignorables such as Zero-Width Joiner and Variation Selectors are removed. These are typically modifier characters that affect display.
  See Also:
    `Normalizer2`, `FilteredNormalizer2`

- - ### 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 and Description
    `ICUNormalizer2Filter(TokenStream input)` Create a new Normalizer2Filter that combines NFKC normalization, Case Folding, and removes Default Ignorables (NFKC_Casefold)
    `ICUNormalizer2Filter(TokenStream input, com.ibm.icu.text.Normalizer2 normalizer)` Create a new Normalizer2Filter with the specified Normalizer2

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `incrementToken()`

    - ### 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, 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 Detail

    - #### ICUNormalizer2Filter

          public ICUNormalizer2Filter(TokenStream input)

      Create a new Normalizer2Filter that combines NFKC normalization, Case Folding, and removes Default Ignorables (NFKC_Casefold)

    - #### ICUNormalizer2Filter

          public ICUNormalizer2Filter(TokenStream input,
                                      com.ibm.icu.text.Normalizer2 normalizer)

      Create a new Normalizer2Filter with the specified Normalizer2
      Parameters:
        `input` - stream
        `normalizer` - normalizer to use

  - ### Method Detail

    - #### incrementToken

          public final boolean incrementToken()
                                       throws IOException

      Specified by:
        `incrementToken` in class `TokenStream`
      Throws:
        `IOException`

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