![]() Interceptors performs tasks such as Logging, Validation, File Upload, Double-submit guard etc. They are invoked by the controller before and after invoking action, thus they sits between the controller and action. Interceptors are responsible for most of the request processing. Struts 2 Interceptors: Basics Struts2 provides very powerful mechanism of controlling a request using Interceptors. We will see what Interceptors are and how to configure them in a Struts2 based web application. Today we will explorer the world of Interceptors in Struts2. In the previous article we saw how to integrate Tiles framework with Struts2. When a lambda expression is evaluated, the compiler can infers it into the interface where default method is added.Welcome to Part-5 of 7-Part series where we are discussing different aspects of Struts2 Framework. What?… I know that’s confusing, but Lambda expressions are the reason why virtual extension methods were introduced in Java 8. Whenever you want to add additional functionality in an existing legacy interface you can use default methods without breaking any existing implementor classes.Īlso abstract classes cannot be root classes in Lambda expression. Default method should be used for backward compatibility. You should still use Abstract class whenever you think your class can have state or you need to do something in constructor. It cannot have constructors and member variables. Whereas interfaces with Java 8 default methods cannot hold state. It can have constructors and member variables. Default method in Java 8 looks similar to Abstract class isn’t it? objects can not be created of) and which may contain method bodies. So how it is different from Abstract classes? Remember an abstract class is a class that can not be instantiated (i.e. ![]() In Java 8 we can have concrete methods within interfaces. override the sayHello to resolve ambiguity void sayHello () Code language: Java ( java ) Difference between default methods and abstract class A key characteristic of extension methods is that they are virtual methods just like other interface methods, but provide a default implementation in the event that the implementing class does not provide a method body. So existing interfaces can be augmented without compromising backward compatibility by adding extension methods to the interface, whose declaration would contain instructions for finding the default implementation in the event that implementors do not provide a method body. ![]() It added a new concept Virtual extension methods, or as they are often called defender methods, can now be added to interfaces providing a default implementation of the declared behaviour. So for backward compatibility, Java 8 cleverly added Default Methods. Imagine in real world how many custom classes would change. You need to add its implementation in every class that implements List interface. ![]() If you add a single method in interface List, it breaks everything. However it is not possible to use this feature in existing Java libraries such as java.util package. A new feature Lambda was introduce which is cool. Since Java 8, things started getting ugly. Once you add a method in interface, all its implemented classes must declare method body of this new method. it is not possible to add a method in interface without breaking the implementor class. Why would one want to add methods into Interfaces? We’ll it is because interfaces are too tightly coupled with their implementation classes. In above Math interface we added a method multiply with actual method body.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |