aeron-io/aeron · error · NullPointerException

input string must not be null or empty

Error message

input string must not be null or empty

What it means

SocketAddressParser.parse throws NullPointerException when the input string is null or empty, before any parsing occurs. The parser requires a concrete host:port string to resolve into an InetSocketAddress. The NPE intentionally encodes 'missing required input'.

Solutions

  1. Ensure the channel URI includes a non-empty endpoint or control value, e.g. aeron:udp?endpoint=127.0.0.1:40456
  2. Check the custom NameResolver implementation's lookup() never returns null/empty for configured names
  3. Catch NullPointerException from parse and log the offending URI parameter name to find the empty value

Example fix

// before
String uri = "aeron:udp?endpoint="; // empty endpoint
// after
String uri = "aeron:udp?endpoint=127.0.0.1:40456";
Defensive patterns

Strategy: validation

Validate before calling

if (value == null || value.isEmpty()) {
    throw new IllegalArgumentException("endpoint/control value for " + paramName + " must not be empty");
}

Try / catch

try {
    InetSocketAddress addr = SocketAddressParser.parse(value, name, false, NameResolver.NULL_NAME_RESOLVER);
} catch (NullPointerException e) {
    // value was null/empty: fix URI or resolver
}

Prevention

When it happens

Trigger: Calling SocketAddressParser.parse(null, ...) or parse("", paramName, ...), typically when a channel URI parameter (endpoint or control) is empty or a NameResolver lookup yields an empty value.

Common situations: Channel URI missing the endpoint value entirely (aeron:udp?endpoint=); URI parameter extraction returning empty string; custom NameResolver returning empty lookup results.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/90f64ff7b8d8e246. Report an issue: GitHub.

Appendix: source

Thrown at aeron-driver/src/main/java/io/aeron/driver/media/SocketAddressParser.java:55

    }

    /**
     * Parse socket addresses from a {@link String}.
     * <p>
     * Supports hostname:port, ipV4Address:port, [ipV6Address]:port, and name.
     *
     * @param value          to be parsed for the socket address.
     * @param uriParamName   for the parse.
     * @param isReResolution for the parse.
     * @param nameResolver   to be used for resolving hostnames.
     * @return An {@link InetSocketAddress} for the parsed input.
     */
    static InetSocketAddress parse(
        final String value, final String uriParamName, final boolean isReResolution, final NameResolver nameResolver)
    {
        if (Strings.isEmpty(value))
        {
            throw new NullPointerException("input string must not be null or empty");
        }

        final String nameAndPort = nameResolver.lookup(value, uriParamName, isReResolution);
        ParseResult result = tryParseIpV4(nameAndPort);
        if (null == result)
        {
            result = tryParseIpV6(nameAndPort);
        }
        if (null == result)
        {
            throw new IllegalArgumentException("invalid format: " + nameAndPort);
        }

        final InetAddress inetAddress = nameResolver.resolve(result.host, uriParamName, isReResolution);
        return null == inetAddress ? InetSocketAddress.createUnresolved(result.host, result.port) :
        new InetSocketAddress(inetAddress, result.port);
    }

View on GitHub (pinned to 6d60124e15)