apache/flink · error · IllegalArgumentException

Invalid input: Empty string

Error message

Invalid input: Empty string

What it means

Thrown by FieldParser.nextStringLength(byte[], int, int, char), the shared helper used by BigDec/BigInt/Double/Float parsers, when length <= 0. Unlike the instance-level parse entry points (which set ParseErrorState and return a status), this static helper throws IllegalArgumentException for an empty input region.

Source

Thrown at flink-core/src/main/java/org/apache/flink/types/parser/FieldParser.java:226

            endPos++;
        }

        if (endPos == startPos) {
            setErrorState(ParseErrorState.EMPTY_COLUMN);
            return -1;
        }
        return endPos;
    }

    /**
     * Returns the length of a string. Throws an exception if the column is empty.
     *
     * @return the length of the string
     */
    protected static final int nextStringLength(
            byte[] bytes, int startPos, int length, char delimiter) {
        if (length <= 0) {
            throw new IllegalArgumentException("Invalid input: Empty string");
        }
        int limitedLength = 0;
        final byte delByte = (byte) delimiter;

        while (limitedLength < length && bytes[startPos + limitedLength] != delByte) {
            limitedLength++;
        }

        return limitedLength;
    }

    /**
     * Gets the character set used for this parser.
     *
     * @return the charset used for this parser.
     */
    public Charset getCharset() {
        return this.charset;

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Check length > 0 (and that the field is not just the delimiter) before calling the static parseField helpers.
2. Fix the record-splitting logic if lengths are computed wrong (off-by-one at row boundaries).
3. Prefer the instance FieldParser API (parseField returning boolean with getErrorState) for per-row error handling instead of the throwing static helpers.

Example fix

// before
int len = FieldParser.nextStringLength(bytes, start, length, delim); // length may be 0

// after
if (length <= 0) { throw new IllegalArgumentException("Empty numeric column at position " + start); }
int len = FieldParser.nextStringLength(bytes, start, length, delim);

if (length <= 0) {
    throw new IllegalArgumentException("Empty field region at start=" + startPos);
}

try {
    int len = FieldParser.nextStringLength(bytes, start, length, delim);
} catch (IllegalArgumentException e) {
    // empty column: default or skip record
}

When it happens

Trigger: Calling nextStringLength directly, or invoking the static parseField of BigIntParser/BigDecParser/DoubleParser/FloatParser with length == 0 — an empty column between delimiters or a miscomputed length argument.

Common situations: Empty numeric columns in delimited text; off-by-one errors in custom splitting code passing zero/negative lengths; trailing-delimiter rows yielding an empty final field.

Related errors

• Invalid input: Empty string
• Empty field.
• Empty field.
• Empty field.
• The output size cannot be smaller than zero.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/995922de66fe52dc. Report an issue: GitHub.