apache/dubbo · error · NoSuchMethodException

class == null

Error message

class == null

What it means

Thrown by ClassUtils.searchMethod when currentClass is null. The method searches for a public method by name and compatible parameter types, but it cannot operate without a class to search, so a null class is rejected up front.

Source

Thrown at dubbo-common/src/main/java/org/apache/dubbo/common/compiler/support/ClassUtils.java:348

                        || type == short.class
                        || type == int.class
                        || type == long.class
                        || type == float.class
                        || type == double.class) {
                    def = "0";
                } else {
                    def = "null";
                }
                buf.append(def);
            }
        }
        return method.getName() + "(" + buf + ")";
    }

    public static Method searchMethod(Class<?> currentClass, String name, Class<?>[] parameterTypes)
            throws NoSuchMethodException {
        if (currentClass == null) {
            throw new NoSuchMethodException("class == null");
        }
        try {
            return currentClass.getMethod(name, parameterTypes);
        } catch (NoSuchMethodException e) {
            for (Method method : currentClass.getMethods()) {
                if (method.getName().equals(name)
                        && parameterTypes.length == method.getParameterTypes().length
                        && Modifier.isPublic(method.getModifiers())) {
                    if (parameterTypes.length > 0) {
                        Class<?>[] types = method.getParameterTypes();
                        boolean match = true;
                        for (int i = 0; i < parameterTypes.length; i++) {
                            if (!types[i].isAssignableFrom(parameterTypes[i])) {
                                match = false;
                                break;
                            }
                        }
                        if (!match) {

View on GitHub (pinned to 3a3043227f)

Solutions

1. Check that currentClass is non-null before calling searchMethod.
2. Trace back to where currentClass was obtained and ensure the type resolution cannot return null.
3. If the class legitimately may be absent, handle null upstream with an early return or clear error.

Example fix

// before
Method m = ClassUtils.searchMethod(maybeNullClass, "doWork", types);
// after
if (maybeNullClass == null) throw new IllegalArgumentException("target class is null");
Method m = ClassUtils.searchMethod(maybeNullClass, "doWork", types);

if (currentClass == null) {
    throw new IllegalArgumentException("target class must not be null");
}
Method m = ClassUtils.searchMethod(currentClass, name, paramTypes);

static boolean hasTargetClass(Class<?> c) {
    return c != null;
}

try {
    Method m = ClassUtils.searchMethod(currentClass, name, paramTypes);
} catch (NoSuchMethodException e) {
    // currentClass was null or method not found; fix upstream null
}

When it happens

Trigger: Calling ClassUtils.searchMethod(null, name, paramTypes), or a caller that resolves the class (e.g. via getClass() on a null object, or a type lookup that returned null) and forwards it without a null check.

Common situations: A reflection-based dispatch path received a null target type — e.g. a service reference whose interface class could not be loaded, or a method lookup on a null return type. Often a symptom of an upstream null rather than a direct call.

Related errors

• Can not create wrapper for primitive type: {}
• pns.length != pvs.length
• task
• object is null
• Invalid configurator rule, please specify at least one param

AI-assisted analysis of apache/dubbo@3a3043227f (2026-08-14). Data as JSON: /api/errors/fba7b2b0d1cd43d2. Report an issue: GitHub.