Java Generics

Level : Advanced
Mentor: Shailendra Chauhan
Duration : 00:02:00

What are Generics in Java?

Generics in Java allow for compile-time type checking, which reduces the chance of ClassCastExceptions, which are especially common in collections. The Java Collection Framework was considerably changed to support generics, boosting type safety. Generic methods and classes now allow explicit type parameterization using angle brackets (< >).

Advantages of Generics

  • Generics give type safety. In generics, we can only hold one type of object.
  • It has a compile-time checker that prevents runtime errors.
  • There is no need to typecast an object.
  • To enable code reuse. We can write a method, class, or interface once and apply it to any type.
  • An object is the superclass of all other classes, and an object reference can point to any type of object. 

Disadvantages of Generics

  • We can't utilize casts or instances with parameterized types.
  • Generic types cannot be instantiated with primitive types.
  • Type parameters cannot be instantiated.
  • Static fields cannot be declared with type arguments as their types.
  • It is not possible to generate arrays with parameterized types.
  • Objects of parameterized types cannot be created, caught, or thrown.

Need of Generics

Type-safe programming in Java is made possible by generics, which improve code reliability and maintainability by enabling classes and methods to work on objects of specified types. They also facilitate code reuse by making it easier to create generic data structures and algorithms that can be applied to a variety of data types.

What are Generics Classes in Java?

Generic classes are defined similarly to regular classes, but include a list of type parameters in angle brackets <...> after the class name. The type parameters can then be used to declare variables and define parameter types for methods throughout the class definition.

Generics with Primitive Types

In Java, generics cannot use primitive types like int or double directly; instead, they must use the same wrapper classes, such as Integer or Double. 

Constraint With Generics

Generics in Java enable the imposition of limits on type parameters through bounded wildcards, assuring compatibility with specified types or subtypes. These limitations improve code clarity and avoid undesired behavior, resulting in robust and error-free implementations.

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