apache/druid · error · NumberFormatException

Cannot parse string to long

Error message

Cannot parse string to long

What it means

Numbers.parseLongObject(String) parses a String to a boxed Long: it first tries Longs.tryParse, then falls back to parsing as a double and truncating via longValue() (to support "ddd.dd"). If neither works, it throws NumberFormatException "Cannot parse string to long".

Solutions

1. Normalize the input first: trim, strip grouping commas and units, then parse.
2. Use the lenient Numbers.tryParseLong(s, nullValue) and check for the sentinel instead of throwing.
3. Catch NumberFormatException and substitute a default/null.
4. Correct upstream data so the field is a plain integer string.

Example fix

// before
Long l = Numbers.parseLongObject(str);
// after
Long l = null;
try {
  l = Numbers.parseLongObject(str.trim());
} catch (NumberFormatException e) {
  l = 0L; /* or log and skip */
}

boolean isLongString(String s) { return s != null && (Longs.tryParse(s.trim()) != null || Doubles.tryParse(s.trim()) != null); }

boolean isLongString(String s) { return s != null && Longs.tryParse(s.trim()) != null; }

Long l;
try { l = Numbers.parseLongObject(s); } catch (NumberFormatException e) { LOG.warn("Unparseable long: %s", s); l = null; }

When it happens

Trigger: Calling Numbers.parseLongObject(s) with a string that is neither an integer nor a double, e.g. "abc", "", "12abc", or numbers with groupings like "1,000,000".

Common situations: Parsing string-typed dimension values or config values expected to be integral; timestamp/ID fields arriving with units or separators.

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

• Cannot parse string to double
• Failed to parse array element
• Invalid format or out of range of long
• Key[ ] should be a long, was[ ]
• Key[ ] should be an int, was[ ]

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/e16755e9851c01e0. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/java/util/common/Numbers.java:207

   * Like {@link #tryParseLong} but does not produce a primitive and will explode if unable to produce a Long
   * similar to {@link Long#parseLong}
   */
  @Nullable
  public static Long parseLongObject(@Nullable String val)
  {
    if (val == null) {
      return null;
    }
    Long lobj = Longs.tryParse(val);
    if (lobj != null) {
      return lobj;
    }
    // try as a double, for "ddd.dd" , Longs.tryParse(..) returns null
    Double dobj = Doubles.tryParse(val);
    if (dobj != null) {
      return dobj.longValue();
    }
    throw new NumberFormatException("Cannot parse string to long");
  }

  private Numbers()
  {
  }
}

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