# LowerCaseFilter (Lucene 3.6.1 API)
Keywords: org.apache.lucene.analysis.LowerCaseFilter class

## org.apache.lucene.analysis
Class LowerCaseFilter

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

All Implemented Interfaces:
  Closeable

    public final class LowerCaseFilter

extends TokenFilter

Normalizes token text to lower case.

You must specify the required `Version` compatibility when creating LowerCaseFilter:

- As of 3.1, supplementary characters are properly lowercased.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
`AttributeSource.AttributeFactory, AttributeSource.State`

Field Summary

Fields inherited from class org.apache.lucene.analysis.TokenFilter
`input`

Constructor Summary
`LowerCaseFilter(TokenStream in)` Deprecated. Use `LowerCaseFilter(Version, TokenStream)` instead.
`LowerCaseFilter(Version matchVersion, TokenStream in)` Create a new LowerCaseFilter, that normalizes token text to lower case.

Method Summary
`boolean` `incrementToken()` Consumers (i.e., `IndexWriter`) use this method to advance the stream to the next token.

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, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Constructor Detail

### LowerCaseFilter

    public LowerCaseFilter(Version matchVersion,
                           TokenStream in)

  Create a new LowerCaseFilter, that normalizes token text to lower case.

  Parameters:
    `matchVersion` - See above
    `in` - TokenStream to filter

### LowerCaseFilter

    @Deprecated
    public LowerCaseFilter(TokenStream in)

  Deprecated. Use `LowerCaseFilter(Version, TokenStream)` instead.

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 `AttributeImpl`s 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 `AttributeImpl`s 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`