org.apache.lucene.analysis

## Class CachingTokenFilter

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

- All Implemented Interfaces:
    Closeable, AutoCloseable

      public final class CachingTokenFilter
      extends TokenFilter

  This class can be used if the token attributes of a TokenStream are intended to be consumed more than once. It caches all token attribute states locally in a List when the first call to `incrementToken()` is called. Subsequent calls will used the cache.

  Important: Like any proper TokenFilter, `reset()` propagates to the input, although only before `incrementToken()` is called the first time. Prior to Lucene 5, it was never propagated.

- - ### 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
    `CachingTokenFilter(TokenStream input)` Create a new CachingTokenFilter around `input`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `end()` This method is called by the consumer after the last token has been consumed, after `TokenStream.incrementToken()` returned `false` (using the new `TokenStream` API).
    `boolean` | `incrementToken()` The first time called, it'll read and cache all tokens from the input.
    `boolean` | `isCached()` If the underlying token stream was consumed and cached.
    `void` | `reset()` Propagates reset if incrementToken has not yet been called.

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

      `close`

    - ### 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

    - #### CachingTokenFilter

          public CachingTokenFilter(TokenStream input)

      Create a new CachingTokenFilter around `input`. As with any normal TokenFilter, do not call reset on the input; this filter will do it normally.

  - ### Method Detail

    - #### reset

          public void reset()
                     throws IOException

      Propagates reset if incrementToken has not yet been called. Otherwise it rewinds the iterator to the beginning of the cached list.
      Overrides:
        `reset` in class `TokenFilter`
      Throws:
        `IOException`

    - #### incrementToken

          public final boolean incrementToken()
                                       throws IOException

      The first time called, it'll read and cache all tokens from the input.
      Specified by:
        `incrementToken` in class `TokenStream`
      Returns:
        false for end of stream; true otherwise
      Throws:
        `IOException`

    - #### end

          public final void end()

      Description copied from class: `TokenFilter`
      This method is called by the consumer after the last token has been consumed, after `TokenStream.incrementToken()` returned `false` (using the new `TokenStream` API). Streams implementing the old API should upgrade to use this feature.

      This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.

      Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.

      If you override this method, always call `super.end()`.

      NOTE: The default implementation chains the call to the input TokenStream, so be sure to call `super.end()` first when overriding this method.

      Overrides:
        `end` in class `TokenFilter`

    - #### isCached

          public boolean isCached()

      If the underlying token stream was consumed and cached.

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