stanfordnlp/CoreNLP · error · IllegalArgumentException

Sentiment analysis is not implemented for German

Error message

Sentiment analysis is not implemented for German

What it means

GermanDocument overrides runSentiment to throw because no sentiment analysis annotator is wired up for German in the simple API. Calling sentiment on a German Document/Sentence throws IllegalArgumentException. It signals an explicitly unimplemented feature for this language, not a configuration error.

Solutions

  1. Remove the 'sentiment' annotator for German documents
  2. Run sentiment only on English documents
  3. Use a German-specific sentiment library/model and merge results
  4. Check the document language before calling sentiment() and branch to a fallback

Example fix

// before
Document doc = new Document(germanText);
String s = doc.sentiment();
// after
if (doc.getClass().getSimpleName().startsWith("German")) {
  throw new UnsupportedOperationException("German sentiment unavailable");
}
String s = doc.sentiment();
Defensive patterns

Strategy: validation

Validate before calling

if (doc instanceof GermanDocument) {
  throw new UnsupportedOperationException("sentiment not supported for German");
}

Type guard

boolean supportsSentiment(Document d) {
  return !(d instanceof GermanDocument);
}

Try / catch

try {
  String s = sentence.sentiment();
} catch (IllegalArgumentException e) {
  s = null; // unsupported for this language
}

Prevention

When it happens

Trigger: Calling Document.runSentiment indirectly via Document.sentiment(), Sentence.sentiment(), or applying the 'sentiment' annotator to German text through StanfordCoreNLP with -language de.

Common situations: Adding the sentiment annotator to a German pipeline; calling sentiment() in a loop over multilingual documents without checking the language; upgrading the simple API and expecting German sentiment support.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/400fad17eaaa2b55. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/simple/GermanDocument.java:83

  protected GermanDocument(Properties props, String text) {
    super(props, text);
  }


  /**
   * No lemma annotator for German -- set the lemma to be the word.
   *
   * @see Document#runLemma(Properties)
   */
  @Override
  protected Document runLemma(Properties props) {
    return mockLemma(props);
  }


  @Override
  protected Document runSentiment(Properties props) {
    throw new IllegalArgumentException("Sentiment analysis is not implemented for German");
  }


  @Override
  public Map<Integer, CorefChain> coref(Properties props) {
    throw new IllegalArgumentException("Coreference is not implemented for German");
  }

}

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