org.apache.lucene.analysis

Class Token

public class Token extends Object implements Cloneable

A Token is an occurence of a term from the text of a field. It consists of a term's text, the start and end offset of the term in the text of the field, and a type string.

The start and end offsets permit applications to re-associate a token with its source text, e.g., to display highlighted query terms in a document browser, or to show matching text fragments in a KWIC (KeyWord In Context) display, etc.

The type is an interned string, assigned by a lexical analyzer (a.k.a. tokenizer), naming the lexical or syntactic class that the token belongs to. For example an end of sentence marker token might be implemented with type "eos". The default token type is "word".

A Token can optionally have metadata (a.k.a. Payload) in the form of a variable length byte array. Use getPayloadLength and (byte[], int) to retrieve the payloads from the index.

WARNING: The status of the Payloads feature is experimental. The APIs introduced here might change in the future and will not be supported anymore in such a case.

See Also: Payload

Constructor Summary
Token(String text, int start, int end)
Constructs a Token with the given term text, and start & end offsets.
Token(String text, int start, int end, String typ)
Constructs a Token with the given text, start and end offsets, & type.
Method Summary
Objectclone()
intendOffset()
Returns this Token's ending offset, one greater than the position of the last character corresponding to this token in the source text.
PayloadgetPayload()
Returns this Token's payload.
intgetPositionIncrement()
Returns the position increment of this Token.
voidsetPayload(Payload payload)
Sets this Token's payload.
voidsetPositionIncrement(int positionIncrement)
Set the position increment.
voidsetTermText(String text)
Sets the Token's term text.
intstartOffset()
Returns this Token's starting offset, the position of the first character corresponding to this token in the source text.
StringtermText()
Returns the Token's term text.
StringtoString()
Stringtype()
Returns this Token's lexical type.

Constructor Detail

Token

public Token(String text, int start, int end)
Constructs a Token with the given term text, and start & end offsets. The type defaults to "word."

Token

public Token(String text, int start, int end, String typ)
Constructs a Token with the given text, start and end offsets, & type.

Method Detail

clone

public Object clone()

endOffset

public final int endOffset()
Returns this Token's ending offset, one greater than the position of the last character corresponding to this token in the source text.

getPayload

public Payload getPayload()
Returns this Token's payload.

WARNING: The status of the Payloads feature is experimental. The APIs introduced here might change in the future and will not be supported anymore in such a case.

getPositionIncrement

public int getPositionIncrement()
Returns the position increment of this Token.

See Also: Token

setPayload

public void setPayload(Payload payload)
Sets this Token's payload.

WARNING: The status of the Payloads feature is experimental. The APIs introduced here might change in the future and will not be supported anymore in such a case.

setPositionIncrement

public void setPositionIncrement(int positionIncrement)
Set the position increment. This determines the position of this token relative to the previous Token in a TokenStream, used in phrase searching.

The default value is one.

Some common uses for this are:

See Also: TermPositions

setTermText

public void setTermText(String text)
Sets the Token's term text.

startOffset

public final int startOffset()
Returns this Token's starting offset, the position of the first character corresponding to this token in the source text. Note that the difference between endOffset() and startOffset() may not be equal to termText.length(), as the term text may have been altered by a stemmer or some other filter.

termText

public final String termText()
Returns the Token's term text.

toString

public String toString()

type

public final String type()
Returns this Token's lexical type. Defaults to "word".
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