alibaba/spring-ai-alibaba · warning · UnsupportedOperationException

Utility class cannot be instantiated

Error message

Utility class cannot be instantiated

What it means

StoreConstant is a constants-only utility class with a private constructor that throws UnsupportedOperationException if instantiated (directly or reflectively). It is a design guard, not a runtime failure of library logic.

Source

Thrown at spring-ai-alibaba-graph-core/src/main/java/com/alibaba/cloud/ai/graph/store/constant/StoreConstant.java:53

	/**
	 * Store type identifiers
	 */
	public static final String STORE_TYPE_MEMORY = "memory";

	public static final String STORE_TYPE_REDIS = "redis";

	public static final String STORE_TYPE_FILESYSTEM = "filesystem";

	public static final String STORE_TYPE_MONGODB = "mongodb";

	public static final String STORE_TYPE_DATABASE = "database";

	/**
	 * Private constructor to prevent instantiation.
	 */
	private StoreConstant() {
		throw new UnsupportedOperationException("Utility class cannot be instantiated");
	}

}

View on GitHub (pinned to f82da0b50f)

Solutions

1. Do not instantiate; reference the public static constants directly (e.g. StoreConstant.STORE_TYPE_DATABASE)
2. If a framework requires instantiation, exclude the class from scanning/serialization
3. In tests, assert the constructor throws rather than constructing it via normal means

Example fix

// before
StoreConstant constants = new StoreConstant();
String type = constants.STORE_TYPE_DATABASE;
// after
String type = StoreConstant.STORE_TYPE_DATABASE;

if (obj instanceof StoreConstant) { throw new AssertionError("StoreConstant must not be instantiated"); }

try { ctor = StoreConstant.class.getDeclaredConstructor(); ctor.setAccessible(true); ctor.newInstance(); } catch (InvocationTargetException e) { /* expected: UnsupportedOperationException */ }

When it happens

Trigger: Calling new StoreConstant(), or reflection/instantiation frameworks (Jackson, Spring bean scanning, code coverage tooling) attempting to construct the class.

Common situations: Accidentally adding StoreConstant as a Spring bean; reflective instantiation in generic serialization code; IDE auto-generating a test that constructs the utility class.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Utility class
• Utility class
• Elastic search index name must be provided
• Param Not Support Object
• Param Not Support Array<Object>

AI-assisted analysis of alibaba/spring-ai-alibaba@f82da0b50f (2026-09-09). Data as JSON: /api/errors/d1053fe1da014f59. Report an issue: GitHub.