Generics yana ba ka rubuta ajami da hanyoyi na wuce-batte ta nau'i, don haka kodun gida gida ya aiki tare da nau'i da yawa yayin daidaita tsaro nau'i a lokacin compilation. Wannan shi ne parametric polymorphism — "siffa guda, kowane nau'i."
();
list.add();
(String) list.get();
// With generics: type is known and checked at compile time
List<String> list = new ArrayList<>();
list.add("hi");
String s = list.get(0); // no cast; list.add(42) won't compile
class Box<T> { // T is a type parameter
private T value;
Box(T value) { this.value = value; }
T get() { return value; }
}
Box<Integer> b = new Box<>(42); // T = Integer, checked at compile time
int n = b.get(); // no cast needed
<T extends Comparable<T>> // bounded: T must be comparable
List<? extends Number> // covariance: accept List<Integer>, List<Double>
Java yana kawar da nau'i na generics a lokacin guida (type erasure) — ba ka iya yin new T() ko instanceof List<String>. C++ templates da C# generics suna da halin daban-daban (monomorphization / reified types).
Generics suna ba da sake amfani da tsaro a lokaci guda: List<T> ɗaya ta aiki tare da duk nau'i na abubuwa, tare da locin jiya na tsara sainin sarraf kuɗi na yau a lokacin guida.
Suna kawar da casts marasa tsaro kuma sune gindin tarin, suna sa kodun ta kasance mafi keyaye kuma mafi wahalar kuma.