stanfordnlp/CoreNLP · error · IllegalArgumentException

Unclosed bracke in encoded array: " + encoded

Error message

Unclosed bracke in encoded array: " + encoded

What it means

Same decoder path for '{'-delimited encoded arrays. If the string starts with '{' the last character must be '}' (note the typo 'bracke' in the message). Otherwise the encoded array is malformed and an IllegalArgumentException is thrown.

Solutions

1. Append the matching '}' as the final character of the encoded string
2. Fix the code that builds the encoded string to emit a matching closing brace
3. Normalize/validate delimiters before decoding
4. Catch IllegalArgumentException and surface a clear parse failure

Example fix

// before
StringUtils.decode("{foo,bar");
// after
StringUtils.decode("{foo,bar}");

if (s != null && s.startsWith("{") && !s.endsWith("}")) throw new IllegalArgumentException("Encoded array must end with '}': " + s);

static boolean isBraceBalanced(String s) { return s != null && s.length() >= 2 && s.charAt(0)=='{' && s.charAt(s.length()-1)=='}'; }

When it happens

Trigger: Calling the public StringUtils decode method with a string whose first character is '{' but whose last character is not '}' (e.g. "{a,b", "{a,b]").

Common situations: Mixing up brace styles when writing encoded values by hand; a generator that emits '{' but a different closer; truncation during copy-paste or serialization.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Unclosed bracket in encoded array: " + encoded
• Last character of encoded array is escape character: " +…
• Unclosed bracket in encoded map: " + encoded
• Unclosed paren in encoded map: " + encoded
• Cannot find matching labelled span for

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/15da41a3b70cf62f. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/util/StringUtils.java:2567

   * or parentheses.
   *
   * @param encoded The String encoding an array
   * @return A String array corresponding to the encoded array
   */
  public static String[] decodeArray(String encoded) {
    if (encoded.isEmpty()) return EMPTY_STRING_ARRAY;
    char[] chars = encoded.trim().toCharArray();

    //--Parse the String
    // (state)
    char quoteCloseChar = (char) 0;
    List<String> terms = new ArrayList<>();
    StringBuilder current = new StringBuilder();
    //(start/stop overhead)
    int start = 0; int end = chars.length;
    if(chars[0] == '('){ start += 1; end -= 1; if(chars[end] != ')') throw new IllegalArgumentException("Unclosed paren in encoded array: " + encoded); }
    if(chars[0] == '['){ start += 1; end -= 1; if(chars[end] != ']') throw new IllegalArgumentException("Unclosed bracket in encoded array: " + encoded); }
    if(chars[0] == '{'){ start += 1; end -= 1; if(chars[end] != '}') throw new IllegalArgumentException("Unclosed bracke in encoded array: " + encoded); }
    // (finite state automaton)
    for (int i=start; i<end; i++) {
      if (chars[i] == '\r') {
        // Ignore funny windows carriage return
        continue;
      } else if (quoteCloseChar != 0) {
        //(case: in quotes)
        if(chars[i] == quoteCloseChar){
          quoteCloseChar = (char) 0;
        }else{
          current.append(chars[i]);
        }
      } else if(chars[i] == '\\'){
        //(case: escaped character)
        if(i == chars.length - 1) throw new IllegalArgumentException("Last character of encoded array is escape character: " + encoded);
        current.append(chars[i+1]);
        i += 1;
      } else {

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