org.apache.lucene.analysis.core

Class UpperCaseFilter

  • All Implemented Interfaces:
    Closeable, AutoCloseable


    public final class UpperCaseFilter
    extends TokenFilter
    Normalizes token text to UPPER CASE.

    NOTE: In Unicode, this transformation may lose information when the upper case character represents more than one lower case character. Use this filter when you require uppercase tokens. Use the LowerCaseFilter for general search matching

    • Constructor Detail

      • UpperCaseFilter

        public UpperCaseFilter(TokenStream in)
        Create a new UpperCaseFilter, that normalizes token text to upper case.
        Parameters:
        in - TokenStream to filter
    • Method Detail

      • incrementToken

        public final boolean incrementToken()
                                     throws IOException
        Description copied from class: TokenStream
        Consumers (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.addAttribute(Class) and 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 TokenStream.incrementToken().

        Specified by:
        incrementToken in class TokenStream
        Returns:
        false for end of stream; true otherwise
        Throws:
        IOException