google/gson · error · IllegalArgumentException

Too big for an int: " + x

Error message

Too big for an int: " + x

What it means

Gson's Calendar/IntegerFieldsTypeAdapter reads year/month/day/hour/minute/second as long values then narrows them to int via the internal toIntExact helper. If a field exceeds Integer.MAX_VALUE or is below Integer.MIN_VALUE, toIntExact throws IllegalArgumentException 'Too big for an int: <x>'. This guards against silent truncation of absurdly large numeric fields.

Source

Thrown at gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java:910

        @Override
        long[] integerValues(Calendar calendar) {
          return new long[] {
            calendar.get(Calendar.YEAR),
            calendar.get(Calendar.MONTH),
            calendar.get(Calendar.DAY_OF_MONTH),
            calendar.get(Calendar.HOUR_OF_DAY),
            calendar.get(Calendar.MINUTE),
            calendar.get(Calendar.SECOND)
          };
        }
      };

  // TODO: update this when we are on at least Android API Level 24.
  private static int toIntExact(long x) {
    int i = (int) x;
    if (i != x) {
      throw new IllegalArgumentException("Too big for an int: " + x);
    }
    return i;
  }

  public static final TypeAdapterFactory CALENDAR_FACTORY =
      newFactoryForMultipleTypes(Calendar.class, GregorianCalendar.class, CALENDAR);

  public static final TypeAdapter<Locale> LOCALE =
      new TypeAdapter<Locale>() {
        @Override
        public Locale read(JsonReader in) throws IOException {
          if (in.peek() == JsonToken.NULL) {
            in.nextNull();
            return null;
          }
          String locale = in.nextString();
          StringTokenizer tokenizer = new StringTokenizer(locale, "_");
          String language = null;

View on GitHub (pinned to 8b8628c656)

Solutions

1. Inspect the offending field reported in the exception and correct the source data.
2. Validate/sanitize the JSON before deserialization, clamping or rejecting out-of-range numbers.
3. Switch to java.time types (Instant, ZonedDateTime) with a proper date-time adapter instead of the legacy Calendar representation.
4. Register a custom TypeAdapter<Calendar> that interprets the numeric fields differently.

Example fix

// before
Calendar cal = gson.fromJson("{\"year\":1700000000000,\"month\":0,...}", Calendar.class);

// after: use java.time + ISO format
Instant inst = gson.fromJson("\"2024-01-01T00:00:00Z\"", Instant.class);

boolean calendarFieldsInRange(long[] v) {
  for (long x : v) if (x < Integer.MIN_VALUE || x > Integer.MAX_VALUE) return false;
  return true;
}

static boolean isIntRange(long x) { return x >= Integer.MIN_VALUE && x <= Integer.MAX_VALUE; }

try {
  Calendar c = gson.fromJson(json, Calendar.class);
} catch (IllegalArgumentException e) {
  // one of the six fields overflowed int; sanitize and retry, or reject
}

When it happens

Trigger: Deserializing a Calendar (legacy mode) where one of the six integer fields (year/month/day/hour/minute/second) is a JSON number outside the int range, e.g. year 5000000000.

Common situations: Garbage or sentinel values from upstream, epoch-millisecond accidentally placed in the year field, or non-Gregorian calendars producing out-of-range components.

Related errors

• duplicate key: {key}
• Expecting number, got: " + jsonToken + "; at path " + in.get
• Unexpected token: " + peeked
• Failed parsing '" + s + "' as BigDecimal; at path " + in.get
• Failed parsing '" + s + "' as BigInteger; at path " + in.get

AI-assisted analysis of google/gson@8b8628c656 (2026-08-04). Data as JSON: /data/errors/195e40ea4def0dca.json. Report an issue: GitHub.