Interfaces, Generics, Type Erasure & PECS Principles
Master polymorphic interface design: default and private interface methods, generic type parameters, compiler type erasure, and PECS wildcards.
Proficiency with Java OOP principles
Complete command of default/private interface methods, generics type erasure, PECS wildcards, and MethodHandles.
Read in order, or jump to what you need.
Every lesson builds on the one before it. Open any lesson to read the explanation, run the examples, and try the practice challenges.
- 04.01Interface Architecture: Contracts, Default Methods & Private Helpers4 min
Explore modern Java interfaces. Understand multiple interface inheritance, default method resolution, and private interface methods.
- 04.02Generics Internals: Type Erasure, Bridge Methods & Reifiable Types4 min
Uncover Java generics runtime mechanics. Understand compile-time type erasure, synthetic bridge methods, and heap pollution hazards.
- 04.03Wildcards, Bounded Generics & The PECS Rule4 min
Master advanced generic variance. Understand invariance, covariance with <? extends T>, contravariance with <? super T>, and Joshua Bloch's PECS rule.
- 04.04Reflection Mechanics, Custom Annotations, and High-Performance MethodHandles4 min
Explore the internals of Java runtime metadata, custom annotation processors, and modern MethodHandles as a high-performance alternative to traditional reflection.
Ready to move on?
Design a generic type-safe event bus enforcing Producer-Extends Consumer-Super variance bounds.
Open the module self-check