6 · Advanced · lesson 40 of 41

Reflection & Annotations

Inspecting and manipulating classes at runtime.

Java
Class<?> c = Class.forName("com.acme.User");
for (var m : c.getDeclaredMethods()) {
    System.out.println(m.getName());
}

// Custom annotation
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@interface Benchmark { }

// Frameworks like Spring/JPA use reflection to wire your code.
Key takeaways
  • ✓Reflection powers frameworks — use it sparingly in app code.
  • ✓Annotations attach metadata for compile-time or runtime tools.
← Back to Java playground