Package org.apache.lucene.analysis.util

# Class CharTokenizer

java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.Tokenizer
org.apache.lucene.analysis.util.CharTokenizer

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`

Direct Known Subclasses:
  `LetterTokenizer`, `UnicodeWhitespaceTokenizer`, `WhitespaceTokenizer`

public abstract class CharTokenizer extends Tokenizer
An abstract base class for simple, character-oriented tokenizers.

The base class also provides factories to create instances of `CharTokenizer` using Java 8 lambdas or method references. It is possible to create an instance which behaves exactly like `LetterTokenizer`:

     Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);

## Nested Class Summary

## Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

`AttributeSource.State`

## Field Summary

Fields
Modifier and Type
Field
Description
`static final int`
`DEFAULT_MAX_WORD_LEN`

### Fields inherited from class org.apache.lucene.analysis.Tokenizer

`input`

### Fields inherited from class org.apache.lucene.analysis.TokenStream

`DEFAULT_TOKEN_ATTRIBUTE_FACTORY`

## Constructor Summary

Constructors
Constructor
Description
`CharTokenizer()`
Creates a new `CharTokenizer` instance
`CharTokenizer(AttributeFactory factory)`
Creates a new `CharTokenizer` instance
`CharTokenizer(AttributeFactory factory, int maxTokenLen)`
Creates a new `CharTokenizer` instance

## Method Summary

Modifier and Type
Method
Description
`final void`
`end()`
`static CharTokenizer`
`fromSeparatorCharPredicate(IntPredicate separatorCharPredicate)`
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
`static CharTokenizer`
`fromSeparatorCharPredicate(AttributeFactory factory, IntPredicate separatorCharPredicate)`
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
`static CharTokenizer`
`fromTokenCharPredicate(IntPredicate tokenCharPredicate)`
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
`static CharTokenizer`
`fromTokenCharPredicate(AttributeFactory factory, IntPredicate tokenCharPredicate)`
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
`final boolean`
`incrementToken()`
`protected abstract boolean`
`isTokenChar(int c)`
Returns true iff a codepoint should be included in a token.
`void`
`reset()`

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

`close, correctOffset, setReader, setReaderTestPoint`

### 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`

## Field Details

### DEFAULT_MAX_WORD_LEN

public static final int DEFAULT_MAX_WORD_LEN

See Also:
  - Constant Field Values

## Constructor Details

### CharTokenizer

public CharTokenizer()
Creates a new `CharTokenizer` instance

### CharTokenizer

public CharTokenizer(AttributeFactory factory)
Creates a new `CharTokenizer` instance

Parameters:
  `factory` - the attribute factory to use for this `Tokenizer`

### CharTokenizer

public CharTokenizer(AttributeFactory factory, int maxTokenLen)
Creates a new `CharTokenizer` instance

Parameters:
  `factory` - the attribute factory to use for this `Tokenizer`
  `maxTokenLen` - maximum token length the tokenizer will emit. Must be greater than 0 and less than MAX_TOKEN_LENGTH_LIMIT (1024*1024)
Throws:
  `IllegalArgumentException` - if maxTokenLen is invalid.

## Method Details

### fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(IntPredicate tokenCharPredicate)
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return `true` for all valid token characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as `LetterTokenizer` is:

     Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);

### fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(AttributeFactory factory, IntPredicate tokenCharPredicate)
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression. The predicate should return `true` for all valid token characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as `LetterTokenizer` is:

     Tokenizer tok = CharTokenizer.fromTokenCharPredicate(factory, Character::isLetter);

### fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(IntPredicate separatorCharPredicate)
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return `true` for all valid token separator characters. This method is provided for convenience to easily use predicates that are negated (they match the separator characters, not the token characters).

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as `WhitespaceTokenizer` is:

     Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(Character::isWhitespace);

### fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(AttributeFactory factory, IntPredicate separatorCharPredicate)
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression. The predicate should return `true` for all valid token separator characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as `WhitespaceTokenizer` is:

     Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(factory, Character::isWhitespace);

### isTokenChar

protected abstract boolean isTokenChar(int c)
Returns true iff a codepoint should be included in a token. This tokenizer generates as tokens adjacent sequences of codepoints which satisfy this predicate. Codepoints for which this is false are used to define token boundaries and are not included in tokens.

### incrementToken

public final boolean incrementToken() throws IOException

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

### end

public final void end() throws IOException

Overrides:
  `end` in class `TokenStream`
Throws:
  `IOException`

### reset

public void reset() throws IOException

Overrides:
  `reset` in class `Tokenizer`
Throws:
  `IOException`