languagetool-org/languagetool · error · RuntimeException

Invalid confidence float value in , expected 'RULE_ID,float_

Error message

Invalid confidence float value in , expected 'RULE_ID,float_value[,...]':

What it means

Each data line of a confidence map file must be 'RULE_ID,float_value' (extra columns allowed for debugging). When the second column cannot be parsed as a float, Float.parseFloat throws NumberFormatException, which load rethrows as a RuntimeException naming the file and offending line.

Source

Thrown at languagetool-server/src/main/java/org/languagetool/server/ConfidenceMapLoader.java:64

    for (Language lang : Languages.get()) {
      int loadCount = 0;
      String fileName = filePattern.getAbsolutePath().replace("{lang}", lang.getShortCode());
      if (!Paths.get(fileName).toFile().exists()) {
        continue;
      }
      List<String> lines = Files.readAllLines(Paths.get(fileName), UTF_8);
      for (String line : lines) {
        if (line.startsWith("#")) {
          continue;
        }
        String[] parts = line.split(",");
        if (parts.length >= 2) {   // there might be more columns for better debugging, but we don't use them here
          try {
            float confidence = Float.parseFloat(parts[1]);
            confMap.put(new ConfidenceKey(lang, parts[0]), confidence);
            loadCount++;
          } catch (NumberFormatException e) {
            throw new RuntimeException("Invalid confidence float value in " + fileName + ", expected 'RULE_ID,float_value[,...]': " + line);
          }
        } else {
          throw new RuntimeException("Invalid line in " + fileName + ", expected 'RULE_ID,float_value[,...]': " + line);
        }
      }
      logger.info("Loaded " + loadCount + " mappings for " + lang + " from confidence map for rules from " + fileName);
    }
    if (confMap.size() == 0) {
      throw new RuntimeException("No confidence values could be loaded for " + filePattern +
        " -- please check there are actually files that match this pattern");
    }
    return confMap;
  }

}

View on GitHub (pinned to 2e990059ce)

Solutions

  1. Fix the offending line so the second column is a valid float using a dot, e.g. 'MY_RULE,0.75'.
  2. Replace decimal commas with dots.
  3. Remove trailing empty columns or stray whitespace/non-numeric characters from the second field.

Example fix

// before
MY_RULE,0,75
// after
MY_RULE,0.75
Defensive patterns

Strategy: validation

Validate before calling

for (const line of lines) {
  const second = line.split('\t')[1];
  if (second === undefined || Number.isNaN(parseFloat(second))) throw new Error('Invalid confidence line: ' + line);
}

Type guard

function isValidConfidenceLine(line) {
  const parts = line.split('\t');
  return parts.length >= 2 && !isNaN(parseFloat(parts[1]));
}

Try / catch

try {
  Map<ConfidenceKey,Float> map = new ConfidenceMapLoader().load(filePattern);
} catch (RuntimeException e) {
  logger.error("Confidence map parse failure: " + e.getMessage());
}

Prevention

When it happens

Trigger: A confidence file for some language contains a line like 'MY_RULE,high' or 'MY_RULE,0,9' (comma decimal separator) or an empty second column.

Common situations: Hand-edited confidence files with decimal commas (locale habit); columns shifted when extra debug columns were added; copy-paste from spreadsheets with localized formatting.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/a683d3a026f75242. Report an issue: GitHub.