Marker Interfaces and Annotations Use Cases and Examples in Java

These mechanisms are useful when code needs to carry meaning beyond ordinary method signatures.

Strong Marker Interface Use Cases

• signaling type-level capability
• constraining generic or API contracts through the type system

Strong Annotation Use Cases

• validation metadata
• framework wiring and configuration
• serialization hints
• custom runtime policies or compile-time tooling

Review Rule

Choose the mechanism that matches the kind of signal:

• type identity -> marker interface
• structured metadata -> annotation