Why Hold Upwards Interface Inward Coffee Or Object Oriented Programming

Many times, I direct maintain seen questions similar why should nosotros locomote interface inwards Java, if nosotros tin non define whatever concrete methods within interface? Or fifty-fifty to a greater extent than common, What is the existent locomote of interface inwards Java? I tin empathise beginners quest this question, when they simply run across mention of the method within interface together with naught else. It takes fourth dimension to realize existent goodness or actual locomote of interface or abstraction inwards Java or whatever object oriented programming. One argue of this is lack of sense inwards actually modelling something existent inwards plan using object oriented analysis together with design. In this article, I volition elbow grease to response this interrogation together with orbit you lot couple of argue to locomote interface inwards your code. If you lot direct maintain practiced agreement of Object oriented basics e.g. Polymorphism, together with thus you lot know that it allows you lot to write flexible code. Interface or abstraction are cardinal to accomplish polymorphism, when a caller locomote interface for calling a method, he innovate flexibility together with dynamism inwards code, every bit that code volition piece of job amongst whatever implementation of that interface, non simply the acquaint concrete implementation. You volition never going to larn this flexibility, if you lot locomote concrete classes for calling methods, nosotros volition run across this inwards to a greater extent than details inwards adjacent section. Also Programming for Interfaces, is likewise good recognized together with 1 of the key object oriented pattern regulation for coding. Another locomote of interface inwards Java is that, it opens novel opportunities for other goodies e.g. pattern patterns. Lot's of pattern patterns are heavily relied on interfaces together with Polymorphism e.g. Decorator, Composite, Proxy or Adapter pattern, all implements same interface, every bit in that place target, together with because they are based on interfaces, they tin hold upwards used interchangeably.

Use Interface for Flexibility together with Polymorphism

As I said, polymorphism is powerful together with provides flexibility together with dynamic demeanour to your code. In gild to convey locomote of Polymorphism, you lot tin either locomote interface or abstract cast inwards Java. Interface provides highest score of abstraction. For event next code, which is based on interfaces, together with an event of programming to interface than implementation principle, is flexible plenty to piece of job amongst whatever Map implementation inwards Java.

Map cache = CacheFactory.getCach(); Employee emp = cache.get("EmployeeID");  // this describe depends upon interface Map, rather than concrete cast e.g. HashMap

If you lot await closely, you lot volition detect that, nearly of the fourth dimension nosotros locomote methods from interface. For example, hither nosotros are using get() method from Map interface, you lot could definitely write next code inwards price of HashMap or Hashtable, but together with thus you lot switched to simply about other implementation e.g. ConcurrentHashMap, you lot demand to alter your code. Here, nosotros are using Map interface for getting Employee object from Cache, which tin hold upwards whatever valid Map implementation, including HashMap, Hashtable, or ConcurrentHashMap. On similar line, you lot should locomote interface every bit Type of method arguments together with every bit render type. This makes your code flexible plenty to operate on whatever implementation.

Use Interface inwards Java to adapt Design patterns

If you lot are familiar of famous GOF pattern patterns than you lot know that nearly of the behavioural pattern locomote Polymorphism for dynamic behaviour, e.g. Decorator pattern, implements same interface every bit the object, which it decorates. If you lot don't locomote interface, it would hold upwards impossible to comprise pattern patterns e.g. if your method convey concrete type, rather than abstract type, together with thus you lot tin non exceed anything else to them. You non exclusively lose flexibility but likewise runtime demeanour enrichment. Similarly, Composite pattern likewise uses same interface every bit object it contains, together with this allows caller to bargain amongst a normal object or composite object inwards same way, had they don't locomote interface, it wasn't possible. Proxy together with Adapter pattern pattern likewise relies on higher flat abstraction e.g. interface or abstract class, to render added behaviour. In short, interface is non simply a practiced coding practice, it likewise opened upwards path to comprise other best practices inwards your code.

Use Interface to aid Unit Testing

Testing is a big describe of piece of job organisation for whatever Project. Project Managers, Technical Pb together with developers volition e'er prefer a code which tin hold upwards unit of measurement tested easily inwards isolation amongst other moving parts. When nosotros locomote interfaces inwards our code, our method get-go depending upon interfaces than implementation, which makes unit of measurement testing extremely easy. For example, a code which is using Database tin non hold upwards tested inwards isolation, until  database is available, but if same code is using interface to interact amongst database layer (DAO pattern pattern), you lot tin e'er render a dummy or mock object to mimic database calls. By using interface inwards your code, you lot larn flexibility everywhere.


That's all on why you lot should locomote interface inwards Java. Though you lot tin non define concrete methods, it's best agency to innovate abstraction inwards your design. Real locomote of interface is to better code character past times allowing modules to depend upon higher flat of abstraction, which is less probable to alter than lower flat concrete classes, which is to a greater extent than probable to change. Use of interface likewise opens opportunities for using tried together with tested Java pattern pattern together with immensely helps inwards Unit testing every bit well. Most importantly, locomote of interface volition orbit you lot unlike flat of thinking together with likely it's 1 measurement inwards mastering object oriented analysis together with design.

Further Learning
SOLID Principles of Object Oriented Design
Absolute Introduction to Object Oriented Programming inwards Java
Java - Object Oriented Programming [For Absolute Beginners]

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