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, AutoCloseable

      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.

- - ### 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.util.CharTokenizer

      `DEFAULT_MAX_WORD_LEN`

    - ### Fields inherited from class org.apache.lucene.analysis.Tokenizer

      `input`

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

      `DEFAULT_TOKEN_ATTRIBUTE_FACTORY`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `LetterTokenizer()` Construct a new LetterTokenizer.
    `LetterTokenizer(AttributeFactory factory)` Construct a new LetterTokenizer using a given `AttributeFactory`.
    `LetterTokenizer(AttributeFactory factory, int maxTokenLen)` Construct a new LetterTokenizer using a given `AttributeFactory`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected boolean` | `isTokenChar(int c)` Collects only characters which satisfy `Character.isLetter(int)`.

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

      `end, fromSeparatorCharPredicate, fromSeparatorCharPredicate, fromTokenCharPredicate, fromTokenCharPredicate, 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, 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

    - #### LetterTokenizer

          public LetterTokenizer()

      Construct a new LetterTokenizer.

    - #### LetterTokenizer

          public LetterTokenizer(AttributeFactory factory)

      Construct a new LetterTokenizer using a given `AttributeFactory`.
      Parameters:
        `factory` - the attribute factory to use for this `Tokenizer`

    - #### LetterTokenizer

          public LetterTokenizer(AttributeFactory factory,
                                 int maxTokenLen)

      Construct a new LetterTokenizer using a given `AttributeFactory`.
      Parameters:
        `factory` - the attribute factory to use for this `Tokenizer`
        `maxTokenLen` - maximum token length the tokenizer will emit. Must be greater than 0 and less than MAX_TOKEN_LENGTH_LIMIT (1024*1024)
      Throws:
        `IllegalArgumentException` - if maxTokenLen is invalid.

  - ### Method Detail

    - #### isTokenChar

          protected boolean isTokenChar(int c)

      Collects only characters which satisfy `Character.isLetter(int)`.
      Specified by:
        `isTokenChar` in class `CharTokenizer`

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