languagetool-org/languagetool · error

Output directory already exists:

Error message

Output directory already exists: 

What it means

TextIndexCreator.main refuses to run when the target output directory already exists, throwing this RuntimeException. It is an overwrite-safety guard: indexing appends many files and the tool avoids silently mixing with a previous run's output.

Source

Thrown at languagetool-dev/src/main/java/org/languagetool/dev/bigdata/TextIndexCreator.java:81

        doc.add(new TextField(Lucene.FIELD_NAME, line, Field.Store.YES));
        doc.add(new TextField(Lucene.FIELD_NAME_LOWERCASE, line.toLowerCase(), Field.Store.YES));
        indexWriter.addDocument(doc);
        if (++lineCount % 10_000 == 0) {
          System.out.println(lineCount + "...");
        }
      }
    }
  }

  public static void main(String[] args) throws IOException {
    if (args.length < 2) {
      System.out.println("Usage: " + TextIndexCreator.class.getSimpleName() + " <outputDir> <inputFile...>");
      System.exit(0);
    }
    TextIndexCreator creator = new TextIndexCreator();
    File outputDir = new File(args[0]);
    if (outputDir.exists()) {
      throw new RuntimeException("Output directory already exists: " + outputDir);
    }
    creator.index(outputDir, Arrays.copyOfRange(args, 1, args.length));
  }
  
}

View on GitHub (pinned to 2e990059ce)

Solutions

1. Delete or rename the existing output directory before re-running
2. Use a new, unique output directory name for each run
3. In automation, use rm -rf or a timestamped directory when a rerun is intentional

Example fix

// before
java TextIndexCreator /data/out corpus.txt   // /data/out exists from previous run
// after
rm -rf /data/out && java TextIndexCreator /data/out corpus.txt
// or: java TextIndexCreator /data/out-$(date +%s) corpus.txt

File outputDir = new File(args[0]);
if (outputDir.exists()) {
  throw new IllegalStateException("Output dir exists, remove or choose another: " + outputDir);
}

try {
  TextIndexCreator.main(args);
} catch (RuntimeException e) {
  if (e.getMessage().startsWith("Output directory already exists")) {
    System.err.println("Delete " + args[0] + " or pick a fresh output dir");
  }
}

When it happens

Trigger: Re-running the tool with the same outputDir argument without deleting the previous run's directory; pointing at an existing directory by mistake.

Common situations: Re-running after a failed/interrupted previous run; scripted retries that reuse args; accidentally using a directory that already holds data.

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

• WrongParameterNumberException
• Unknown level '<level>' - currently, only 'PICKY' is support
• You cannot list unknown words when tagging only
• You cannot apply suggestions when tagging only
• You cannot specify both disabled rules and enabledonly

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/c34f4ee71f8f8647. Report an issue: GitHub.