Java Generics

Java generics is a feature that allows you to create “parameterized data types”. For example, instead of just declaring a collection that can store any data you can pass it a parameter to allow only the objects of certain data types.

Instead of declaring and instantiating a general collection to store pets like this:

  ​ArrayList pets = new ArrayList();

you can do it with a parameter so it can store only String objects like this:

  ​ArrayList<String> pets = new ArrayList<>();

Advantages of using generics

  • Generics ensure compile-time safety which allows the programmer to catch the invalid types while compiling the code.

  • Java Generics helps the programmer to reuse the code for whatever type he/she wishes. For instance, a programmer writes a generic method for sorting an array of objects. Generics allow the programmer to use the same method for Integer arrays, Double arrays, and even String arrays.

  • Another advantage of using generics is that Individual typecasting isn’t required. The programmer defines the initial type and then lets the code do its job.

  • It allows us to implement non-generic algorithms.

Types of Java Generics

  • Generic method: Generic Java method takes a parameter and returns some value after performing a task. It is exactly like a normal function, however, a generic method has type parameters which are reproduced by actual type. This allows the generic method to be used in a more general way. The compiler takes care of the type of safety which enables programmers to code easily since they do not have to perform long, individual type castings.
public static <T> int getPets(T[] list, T item) {}
  • Generic classes: A generic class is implemented exactly like a non-generic class. The only difference is that it contains a type parameter section. There can be more than one type of parameter, separated by a comma. The classes, which accept one or more parameters, ​are known as parametrized classes or parameterized types.
class DemoClass<T> {}

Tutorial

Please go through this tutorial to give yourself a better chance to understand the topic

https://howtodoinjava.com/java/generics/complete-java-generics-tutorial/

Resource

https://www.educative.io/edpresso/what-are-generics-in-java?https://www.educative.io/courses/grokking-the-object-oriented-design-interview?aid=5082902844932096&utm_source=google&utm_medium=cpc&utm_campaign=blog-dynamic&gclid=Cj0KCQiAvc_xBRCYARIsAC5QT9lk7E9OCRYSk5j9kKNwDjsatXCWMIRxr1bGagOKo9jcfk3njeeokRsaAoerEALw_wcB

https://www.tutorialspoint.com/java/java_generics.htm

https://howtodoinjava.com/java/generics/complete-java-generics-tutorial/

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