Generics Fundamentals

Generics in Java provide a way to define classes, interfaces, and methods with a placeholder for types. They allow for type safety and code reusability without the need for casting.

Why Generics?

  • Type Safety: Compile-time checking prevents runtime ClassCastException.
  • Code Reusability: One class or method works with different types.
  • Eliminates Casting: Reduces boilerplate casting code.

Example Without Generics

ArrayList list = new ArrayList();
list.add("Hello");
String s = (String) list.get(0); // requires casting

Example With Generics

ArrayList<String> list = new ArrayList<>();
list.add("Hello");
String s = list.get(0); // no casting required

Generic Syntax

class Box<T> {
    T item;
    void set(T item) { this.item = item; }
    T get() { return item; }
}

Benefits

  • Prevents runtime errors
  • More readable and maintainable code
  • Encourages clean APIs

🔗 Related Notes