Java generics: Generic classes, generic interfaces, and generic methods

Source: 1190000002646193

Generic class

 Public classContainer<k, v> {    PrivateK Key; PrivateV value;  PublicContainer (k K, v V) {key=K; Value=v; }     PublicK GetKey () {returnkey; }     Public voidSetkey (K key) { This. Key =key; }     PublicV GetValue () {returnvalue; }     Public voidSetValue (V value) { This. Value =value; }}

Generic interface

 Public Interface Generator<t> {    public  T Next ();}

 Public class Implements Generator<string> {    privatenew string[]{"Apple", "Banana", "Pear"};    @Override    public  String Next () {        new  Random ();         return fruits[rand.nextint (3)];}    }

Generic methods (a basic principle: use generic methods as much as possible )

     Public Static void out (T-t) {        System.out.println (t);    }

Type wildcard character (in common method, used when no generic method is used)

Upper limit: <? Extends T>? is a subclass of T and T

Lower limit: <? Super T>? is the parent class of T and T

Java generics: Generic classes, generic interfaces, and generic methods