- Direct Known Subclasses:
public abstract class CharTokenizer extends TokenizerAn abstract base class for simple, character-oriented tokenizers.
- As of 3.1,
CharTokenizeruses an int based API to normalize and detect token codepoints. See
CharTokenizerAPI has been introduced with Lucene 3.1. This API moved from UTF-16 code units to UTF-32 codepoints to eventually add support for supplementary characters. The old char based API has been deprecated and should be replaced with the int based methods
As of Lucene 3.1 each
CharTokenizer- constructor expects a
Versionargument. Based on the given
Versioneither the new API or a backwards compatibility layer is used at runtime. For
Version< 3.1 the backwards compatibility layer ensures correct behavior even for indexes build with previous versions of Lucene. If a
Version>= 3.1 is used
CharTokenizerrequires the new API to be implemented by the instantiated class. Yet, the old char based API is not required anymore even if backwards compatibility must be preserved.
CharTokenizersubclasses implementing the new API are fully backwards compatible if instantiated with
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
end()This method is called by the consumer after the last token has been consumed, after
false(using the new
IndexWriter) use this method to advance the stream to the next token.
reset()This method is called by a consumer before it begins consumption using
Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
matchVersion- Lucene version to match
input- the input to split up into tokens
public final boolean incrementToken() throws IOExceptionConsumers (i.e.,
IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate
AttributeImpls with the attributes of the next token.
The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use
AttributeSource.captureState()to create a copy of the current attribute state.
This method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to
AttributeSource.getAttribute(Class), references to all
AttributeImpls that this stream uses should be retrieved during instantiation.
To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in
public final void end() throws IOExceptionThis method is called by the consumer after the last token has been consumed, after
false(using the new
TokenStreamAPI). 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
public void reset() throws IOExceptionThis method is called by a consumer before it begins consumption using
Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.