languagetool-org/languagetool · error · IllegalArgumentException

Unknown value '${indexPos}' for indexPosTags parameter, use

Error message

Unknown value '${indexPos}' for indexPosTags parameter, use 0 or 1

What it means

SentenceSourceIndexer.main takes the indexPosTags argument (args[4]) which selects whether positional tags are indexed: '0' uses StandardAnalyzer (no position tags), '1' uses LanguageToolAnalyzer. Any other value throws an IllegalArgumentException. It is a strict two-value enum check on a CLI parameter.

Source

Thrown at languagetool-wikipedia/src/main/java/org/languagetool/dev/dumpcheck/SentenceSourceIndexer.java:152

    String languageCode = args[2];
    int maxSentences = Integer.parseInt(args[3]);

    Language language = Languages.getLanguageForShortCode(languageCode);
    if (maxSentences == 0) {
      System.out.println("Going to index contents from " + dumpFilesNames);
    } else {
      System.out.println("Going to index up to " + maxSentences + " sentences from " + dumpFilesNames);
    }
    System.out.println("Output index dir: " + indexDir);
    long start = System.currentTimeMillis();
    Analyzer analyzer;
    String indexPos = args[4];
    if (indexPos.equals("1")) {
      analyzer = null;  // this will use LanguageToolAnalyzer
    } else if (indexPos.equals("0")) {
      analyzer = new StandardAnalyzer(new CharArraySet(Collections.emptyList(), false));
    } else {
      throw new IllegalArgumentException("Unknown value '" + indexPos + "' for indexPosTags parameter, use 0 or 1");
    }
    try (FSDirectory fsDirectory = FSDirectory.open(indexDir.toPath());
         SentenceSourceIndexer indexer = new SentenceSourceIndexer(fsDirectory, language, maxSentences, analyzer)) {
      try {
        indexer.run(dumpFilesNames, language);
      } catch (DocumentLimitReachedException e) {
        System.out.println("Sentence limit (" + e.getLimit() + ") reached, stopping indexing");
      } finally {
        indexer.writeMetaDocuments();
      }
      if (analyzer != null) {
        analyzer.close();
      }
    }
    long end = System.currentTimeMillis();
    float minutes = (end - start) / (float)(1000 * 60);
    System.out.printf("Indexing took %.2f minutes\n", minutes);
  }

View on GitHub (pinned to 2e990059ce)

Solutions

  1. Pass exactly 0 or 1 as the fifth argument
  2. Trim quotes/whitespace in the calling script
  3. Check your wrapper script's argument ordering so args[4] is really the indexPosTags value

Example fix

// before
java ... indexDir en dump.xml maxSentences true
// after
java ... indexDir en dump.xml maxSentences 1
Defensive patterns

Strategy: validation

Validate before calling

String indexPos = args[4];
if (!indexPos.equals("0") && !indexPos.equals("1")) {
  System.err.println("indexPosTags must be 0 or 1, got: " + indexPos);
  System.exit(2);
}

Try / catch

try {
  SentenceSourceIndexer.main(args);
} catch (IllegalArgumentException e) {
  if (e.getMessage() != null && e.getMessage().startsWith("Unknown value")) {
    System.err.println("Fix the 5th argument (indexPosTags): " + e.getMessage());
  } else throw e;
}

Prevention

When it happens

Trigger: Calling the indexer with a 5th argument that isn't exactly "0" or "1", e.g. "true", "yes", "0 " with whitespace, or "no".

Common situations: Scripts passing boolean words instead of digits; copy-paste with trailing whitespace or quotes; outdated documentation suggesting other values.

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/346c7194234feaf8. Report an issue: GitHub.