Why Hold Upwardly Interface Inwards Coffee Or Object Oriented Programming

Many times, I possess got seen questions similar why should nosotros operate interface inwards Java, if nosotros tin mail away non define whatever concrete methods within interface? Or fifty-fifty to a greater extent than common, What is the existent operate of interface inwards Java? I tin mail away sympathise beginners bespeak this question, when they but encounter elevate of the method within interface together with zero else. It takes fourth dimension to realize existent goodness or actual operate 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 computer program using object oriented analysis together with design. In this article, I volition endeavor to respond this interrogation together with plough over you lot couple of argue to operate interface inwards your code. If you lot possess got skillful agreement of Object oriented basics e.g. Polymorphism, hence you lot know that it allows you lot to write flexible code. Interface or abstraction are fundamental to attain polymorphism, when a caller operate interface for calling a method, he innovate flexibility together with dynamism inwards code, equally that code volition piece of occupation alongside whatever implementation of that interface, non but the acquaint concrete implementation. You volition never going to instruct this flexibility, if you lot operate concrete classes for calling methods, nosotros volition encounter this inwards to a greater extent than details inwards side yesteryear side section. Also Programming for Interfaces, is equally good well recognized together with i of the key object oriented blueprint regulation for coding. Another operate of interface inwards Java is that, it opens novel opportunities for other goodies e.g. blueprint patterns. Lot's of blueprint patterns are heavily relied on interfaces together with Polymorphism e.g. Decorator, Composite, Proxy or Adapter pattern, all implements same interface, equally at that spot target, together with because they are based on interfaces, they tin mail away hold upwardly used interchangeably.

Use Interface for Flexibility together with Polymorphism

As I said, polymorphism is powerful together with provides flexibility together with dynamic demeanor to your code. In lodge to convey operate of Polymorphism, you lot tin mail away either operate interface or abstract marking inwards Java. Interface provides highest marking of abstraction. For instance next code, which is based on interfaces, together with an instance of programming to interface than implementation principle, is flexible plenty to piece of occupation alongside whatever Map implementation inwards Java.

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

If you lot await closely, you lot volition detect that, nigh of the fourth dimension nosotros operate 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 hence you lot switched to but 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 mail away hold upwardly whatever valid Map implementation, including HashMap, Hashtable, or ConcurrentHashMap. On similar line, you lot should operate interface equally Type of method arguments together with equally 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 blueprint patterns than you lot know that nigh of the behavioural pattern operate Polymorphism for dynamic behaviour, e.g. Decorator pattern, implements same interface equally the object, which it decorates. If you lot don't operate interface, it would hold upwardly impossible to contain blueprint patterns e.g. if your method convey concrete type, rather than abstract type, hence you lot tin mail away non transcend anything else to them. You non alone lose flexibility but equally good runtime demeanor enrichment. Similarly, Composite pattern equally good uses same interface equally object it contains, together with this allows caller to bargain alongside a normal object or composite object inwards same way, had they don't operate interface, it wasn't possible. Proxy together with Adapter blueprint pattern equally good relies on higher bird abstraction e.g. interface or abstract class, to render added behaviour. In short, interface is non but a skillful coding practice, it equally good opened upwardly path to contain other best practices inwards your code.

Use Interface to assist Unit Testing

Testing is a big trace organisation for whatever Project. Project Managers, Technical Pb together with developers volition ever prefer a code which tin mail away hold upwardly unit of measurement tested easily inwards isolation alongside other moving parts. When nosotros operate interfaces inwards our code, our method starting fourth dimension depending upon interfaces than implementation, which makes unit of measurement testing extremely easy. For example, a code which is using Database tin mail away non hold upwardly tested inwards isolation, until  database is available, but if same code is using interface to interact alongside database layer (DAO blueprint pattern), you lot tin mail away ever render a dummy or mock object to mimic database calls. By using interface inwards your code, you lot instruct flexibility everywhere.


That's all on why you lot should operate interface inwards Java. Though you lot tin mail away non define concrete methods, it's best agency to innovate abstraction inwards your design. Real operate of interface is to meliorate code lineament yesteryear allowing modules to depend upon higher bird of abstraction, which is less probable to alter than lower bird concrete classes, which is to a greater extent than probable to change. Use of interface equally good opens opportunities for using tried together with tested Java blueprint pattern together with immensely helps inwards Unit testing equally well. Most importantly, operate of interface volition plough over you lot dissimilar bird of thinking together with in all probability it's i mensuration 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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