A generic class, interface or method in Java is parameterized by one or more types. Generics in Java allow one implementation of a collection or algorithm to be reused with different reference types while checking the allowed values and results statically. For example:The type parameter is declared inside angle brackets, as in
Vector<String> names = new Vector<String>();
names.add("Ada");
String first = names.get(0);
class Box<T> {
private T value;
public void put(T x) { value = x; }
public T get() { return value; }
}Box<T>, and supplied as a type argument, as in Box<String>. A generic method places its parameter list before its return type, for example static <T> T identity(T x). Bounds such as <T extends Number> restrict type arguments, and wildcards such as ? extends Number or ? super Integer describe restricted views. Primitive values require wrapper types such as Integer rather than a type argument int. Generics provide reusable code with compile-time checking of element types. Articles by others on the same topic
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