Wildcards

Java Generics Cheat Sheet

Reference for Java generic classes, methods, bounded type parameters, wildcards, and type erasure for type-safe reusable code.

Covariance and Contravariance Explained

Covariance and contravariance describe how subtyping relationships between types carry over to derived types like arrays, generics, and function signatures — c…

What Are Generics in Java?

Generics let a class, interface, or method be parameterized over types, so the same code works with different data types while the compiler enforces type safet…

Bounded Type Parameters Explained

A bounded type parameter restricts a generic type parameter to a specific type or its subtypes, written as `<T extends Upper>` in Java, so the generic class or…