Generics
Generics let classes, interfaces, and methods operate on typed parameters specified at compile time (e.g., List<String>), giving compile-time type safety and eliminating the need for manual casting that pre-Java-5 code required when using collections of Object.
Without generics: cast at every read, risk at runtime · With generics: checked at compile time
java
// Without generics (pre-Java 5 style)
List list = new ArrayList();
list.add("hello");
String s = (String) list.get(0); // manual cast, runtime risk
// With generics
List<String> typedList = new ArrayList<>();
typedList.add("hello");
String s2 = typedList.get(0); // no cast needed, compiler-checked