spring-projects/spring-framework · error · IllegalArgumentException

Number of 'constructorArgs' ({}) must match number of 'const

Error message

Number of 'constructorArgs' ({}) must match number of 'constructorArgTypes' ({})

What it means

setConstructorArguments() (line 150) requires the values array and the types array to have the same length, because each arg must be paired with exactly one declared parameter type for constructor resolution. A length mismatch means the inputs cannot describe a single constructor invocation.

Source

Thrown at spring-aop/src/main/java/org/springframework/aop/framework/CglibAopProxy.java:151

	 * exception in this case, rather than let a mysterious failure happen later.
	 */
	public CglibAopProxy(AdvisedSupport config) throws AopConfigException {
		Assert.notNull(config, "AdvisedSupport must not be null");
		this.advised = config;
		this.advisedDispatcher = new AdvisedDispatcher(this.advised);
	}

	/**
	 * Set constructor arguments to use for creating the proxy.
	 * @param constructorArgs the constructor argument values
	 * @param constructorArgTypes the constructor argument types
	 */
	public void setConstructorArguments(Object @Nullable [] constructorArgs, Class<?> @Nullable [] constructorArgTypes) {
		if (constructorArgs == null || constructorArgTypes == null) {
			throw new IllegalArgumentException("Both 'constructorArgs' and 'constructorArgTypes' need to be specified");
		}
		if (constructorArgs.length != constructorArgTypes.length) {
			throw new IllegalArgumentException("Number of 'constructorArgs' (" + constructorArgs.length +
					") must match number of 'constructorArgTypes' (" + constructorArgTypes.length + ")");
		}
		this.constructorArgs = constructorArgs;
		this.constructorArgTypes = constructorArgTypes;
	}


	@Override
	public Object getProxy() {
		return buildProxy(null, false);
	}

	@Override
	public Object getProxy(@Nullable ClassLoader classLoader) {
		return buildProxy(classLoader, false);
	}

	@Override

View on GitHub (pinned to 69bf83ad71)

Solutions

1. Make the two arrays the same length, pairing every value with its type
2. Build them together: for each (value,type) pair push to both arrays in one loop
3. Add an assertion: if (args.length != types.length) throw before calling the API

Example fix

// before
proxy.setConstructorArguments(new Object[]{1, "x"}, new Class[]{int.class});

// after
proxy.setConstructorArguments(new Object[]{1, "x"}, new Class[]{int.class, String.class});

if (constructorArgs.length != constructorArgTypes.length) {
  throw new IllegalArgumentException("constructorArgs/constructorArgTypes length mismatch");
}

private static boolean constructorArgsConsistent(Object[] args, Class<?>[] types) {
  return args != null && types != null && args.length == types.length;
}

When it happens

Trigger: Passing constructorArgs and constructorArgTypes of different lengths, e.g. 3 values but 2 types.

Common situations: Appending an argument but forgetting to add its type; copying arrays of unequal size; off-by-one when building the two arrays in a loop.

Related errors

• Both 'constructorArgs' and 'constructorArgTypes' need to be
• An advice method can never be a constructor
• Failed to invoke aspect constructor: {aspectClass.getName()}
• Property 'targetBeanName' is required
• Property 'methodName' is required

AI-assisted analysis of spring-projects/spring-framework@69bf83ad71 (2026-08-09). Data as JSON: /api/errors/fde95906c71a2402. Report an issue: GitHub.