Package org.apache.lucene.analysis.en

# Class PorterStemFilter

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

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`, `Unwrappable<TokenStream>`

public final class PorterStemFilter extends TokenFilter
Transforms the token stream as per the Porter stemming algorithm. Note: the input to the stemming filter must already be in lower case, so you will need to use LowerCaseFilter or LowerCaseTokenizer farther down the Tokenizer chain in order for this to work properly!

To use this filter with other analyzers, you'll want to write an Analyzer class that sets up the TokenStream chain as you want it. To use this with LowerCaseTokenizer, for example, you'd write an analyzer like this:

     class MyAnalyzer extends Analyzer {
       @Override
       protected TokenStreamComponents createComponents(String fieldName) {
         Tokenizer source = new LowerCaseTokenizer(version, reader);
         return new TokenStreamComponents(source, new PorterStemFilter(source));
       }
     }

Note: This filter is aware of the `KeywordAttribute`. To prevent certain terms from being passed to the stemmer `KeywordAttribute.isKeyword()` should be set to `true` in a previous `TokenStream`.

Note: For including the original term as well as the stemmed version, see `KeywordRepeatFilterFactory`

## 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
Description
`PorterStemFilter(TokenStream in)`

## Method Summary

Modifier and Type
Method
Description
`final boolean`
`incrementToken()`

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

`close, end, reset, unwrap`

### 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 Details

### PorterStemFilter

public PorterStemFilter(TokenStream in)

## Method Details

### incrementToken

public final boolean incrementToken() throws IOException

Specified by:
  `incrementToken` in class `TokenStream`
Throws:
  `IOException`