EntityLinker (Apache OpenNLP Tools 1.9.5 API)
Date: 2026-06-18

opennlp.tools.entitylinker

## Interface EntityLinker<T extends Span>

- Type Parameters:
    `T` - A type that extends Span. LinkedSpan and BaseLink are provided to provide this signature: EntityLinker<LinkedSpan<BaseLink>> as a default

      public interface EntityLinker<T extends Span>

  EntityLinkers establish connections to external data to enrich extracted entities. For instance, for Location entities a linker can be developed to lookup each found location in a geonames gazateer. Another example may be to find peoples' names and look them up in a database or active directory. Intended to return n best matches for any give search, but can also be implemented as deterministic

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `List<T>` | `find(String doctext, Span[] sentences, Span[][] tokensBySentence, Span[][] namesBySentence)` Links an entire document of named entities to an external source
    `List<T>` | `find(String doctext, Span[] sentences, Span[][] tokensBySentence, Span[][] namesBySentence, int sentenceIndex)` Links the names that correspond to the tokens[] spans.
    `void` | `init(EntityLinkerProperties initializationData)` allows for passing properties through the EntityLinkerFactory into all impls dynamically.

- - ### Method Detail

    - #### init

          void init(EntityLinkerProperties initializationData)
             throws IOException

      allows for passing properties through the EntityLinkerFactory into all impls dynamically. EntityLinker impls should initialize reusable objects used by the impl in this method. If this is done, any errors will be captured and thrown by the EntityLinkerFactory.
      Parameters:
        `initializationData` - the EntityLinkerProperties object that contains properties needed by the impl, as well as any other objects required for the impl
      Throws:
        `IOException`

    - #### find

          List<T> find(String doctext,
                       Span[] sentences,
                       Span[][] tokensBySentence,
                       Span[][] namesBySentence)

      Links an entire document of named entities to an external source
      Parameters:
        `doctext` - the full text of the document
        `tokensBySentence` - a list of tokens spans that correspond to each sentence. The outer array refers to the sentence, the inner array is the tokens for the outer sentence. Similar in nature to Map of SentenceIndex keys to Listof tokens as values
        `namesBySentence` - a list of name spans that correspond to each sentence. The outer array refers to the sentence, the inner array refers to the tokens that for the same sentence.Similar in nature to Map<SentenceIndex,List<Name Spans For This Sentence's Tokens>> @ return
      Returns:

    - #### find

          List<T> find(String doctext,
                       Span[] sentences,
                       Span[][] tokensBySentence,
                       Span[][] namesBySentence,
                       int sentenceIndex)

      Links the names that correspond to the tokens[] spans. The sentenceindex can be used to get the sentence text and tokens from the text based on the sentence and token spans. The text is available for additional context.
      Parameters:
        `doctext` - the full text of the document
        `tokensBySentence` - a list of tokens spans that correspond to each sentence. The outer array refers to the sentence, the inner array is the tokens for the outer sentence. Similar in nature to Map of SentenceIndex keys to Listof tokens as values
        `namesBySentence` - a list of name spans that correspond to each sentence. The outer array refers to the sentence, the inner array refers to the tokens that for the same sentence.Similar in nature to Map<SentenceIndex,List<Name Spans For This Sentence's Tokens>> @ return
        `sentenceIndex` - the index to the sentence span that the tokens[] Span[] corresponds to
      Returns:

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