apache/shardingsphere · error · ClassCastException

Unsupported type conversion from %s to %s

Error message

Unsupported type conversion from %s to %s

What it means

A plain ClassCastException ('Unsupported type conversion from X to Y') thrown by ShardingValueTypeConvertUtils.convert when the runtime value's class has no conversion branch to the requested temporal target (LocalDateTime, Instant, Year, YearMonth, MonthDay, Duration — and the earlier branches). The utility converts sharding/route values between Java types; unsupported source/target pairs fall through to this explicit throw instead of failing obscurely inside JDK casts.

Source

Thrown at features/sharding/core/src/main/java/org/apache/shardingsphere/sharding/util/ShardingValueTypeConvertUtils.java:123

            return (T) convertToTimestamp(value);
        } else if (LocalDate.class == targetType) {
            return (T) convertToLocalDate(value);
        } else if (LocalTime.class == targetType) {
            return (T) convertToLocalTime(value);
        } else if (LocalDateTime.class == targetType) {
            return (T) convertToLocalDateTime(value);
        } else if (Instant.class == targetType) {
            return (T) convertToInstant(value);
        } else if (Year.class == targetType) {
            return (T) convertToYear(value);
        } else if (YearMonth.class == targetType) {
            return (T) convertToYearMonth(value);
        } else if (MonthDay.class == targetType) {
            return (T) convertToMonthDay(value);
        } else if (Duration.class == targetType) {
            return (T) convertToDuration(value);
        }
        throw new ClassCastException("Unsupported type conversion from " + value.getClass().getName() + " to " + targetType.getName());
    }
    
    private static Integer convertToInteger(final Comparable<?> value) {
        if (value instanceof Number) {
            return ((Number) value).intValue();
        }
        return Integer.parseInt(value.toString());
    }
    
    private static Long convertToLong(final Comparable<?> value) {
        if (value instanceof Number) {
            return ((Number) value).longValue();
        }
        return Long.parseLong(value.toString());
    }
    
    private static Short convertToShort(final Comparable<?> value) {
        if (value instanceof Number) {

View on GitHub (pinned to e952770a21)

Solutions

  1. Bind sharding parameters using a type this utility converts (String, Number, java.time types listed in its branches — LocalDate/LocalDateTime/Instant/Year/YearMonth/MonthDay/Duration).
  2. Convert the value in application code before sending (e.g. java.util.Date -> java.time.LocalDateTime) so the utility receives a supported class.
  3. For custom algorithms, do the conversion inside the algorithm rather than relying on ShardingValueTypeConvertUtils for unsupported pairs.

Example fix

// before: java.util.Date sharding value, target LocalDateTime
ps.setDate(1, new java.util.Date(millis));

// after: bind a supported java.time type
ps.setObject(1, LocalDateTime.ofInstant(Instant.ofEpochMilli(millis), ZoneId.systemDefault()));
Defensive patterns

Strategy: type-guard

Validate before calling

// Convert bind values to supported types before setting
Object v = toSupported(value);
Object toSupported(Object value) {
    if (value instanceof java.util.Date d) return LocalDateTime.ofInstant(d.toInstant(), ZoneId.systemDefault());
    return value;
}

Type guard

boolean isConvertibleShardingValue(final Object value) {
    return value instanceof String
            || value instanceof Number
            || value instanceof java.time.LocalDate
            || value instanceof java.time.LocalDateTime
            || value instanceof java.time.LocalTime
            || value instanceof java.time.Instant
            || value instanceof java.time.Year
            || value instanceof java.time.YearMonth
            || value instanceof java.time.MonthDay
            || value instanceof java.time.Duration
            || value instanceof Boolean;
}

Try / catch

try {
    return ShardingValueTypeConvertUtils.convert(value, targetType);
} catch (final ClassCastException ex) {
    // message names source and target classes; convert value manually and retry
}

Prevention

When it happens

Trigger: A sharding value whose Java type does not match the strategy/algorithm's expected type — e.g. passing a java.util.Date or byte[] where the sharding algorithm asks to convert to LocalDateTime, or a target type added to the enum without a corresponding converter branch in this utility.

Common situations: Custom sharding algorithms typed to a specific temporal class while the application binds a different temporal type; dialect upgrades changing the parsed literal class; using an exotic Comparable (e.g. YearWeek) with a strategy that requests a supported-but-unconvertible target.

Related errors

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/136bd164b8f8cd19. Report an issue: GitHub.