Why Purpose Interface Inwards Coffee Or Object Oriented Programming

Many times, I conduct maintain seen questions similar why should nosotros role 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 role of interface inwards Java? I tin sympathize beginners quest this question, when they only run into advert of the method within interface in addition to zero else. It takes fourth dimension to realize existent goodness or actual role 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 in addition to design. In this article, I volition endeavor to answer this enquiry in addition to laissez passer on yous couple of argue to role interface inwards your code. If yous conduct maintain skillful agreement of Object oriented basics e.g. Polymorphism, in addition to thence yous know that it allows yous to write flexible code. Interface or abstraction are fundamental to accomplish polymorphism, when a caller role interface for calling a method, he innovate flexibility in addition to dynamism inwards code, equally that code volition move amongst whatever implementation of that interface, non only the introduce concrete implementation. You volition never going to larn this flexibility, if yous role concrete classes for calling methods, nosotros volition run into this inwards to a greater extent than details inwards side past times side section. Also Programming for Interfaces, is besides good recognized in addition to i of the key object oriented blueprint regulation for coding. Another role 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 in addition to Polymorphism e.g. Decorator, Composite, Proxy or Adapter pattern, all implements same interface, equally at that topographic point target, in addition to because they are based on interfaces, they tin hold upward used interchangeably.

Use Interface for Flexibility in addition to Polymorphism

As I said, polymorphism is powerful in addition to provides flexibility in addition to dynamic behavior to your code. In guild to convey role of Polymorphism, yous tin either role interface or abstract class inwards Java. Interface provides highest marking of abstraction. For event next code, which is based on interfaces, in addition to an event of programming to interface than implementation principle, is flexible plenty to move amongst whatever Map implementation inwards Java.

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

If yous await closely, yous volition notice that, almost of the fourth dimension nosotros role methods from interface. For example, hither nosotros are using get() method from Map interface, yous could definitely write next code inwards price of HashMap or Hashtable, but in addition to thence yous switched to roughly other implementation e.g. ConcurrentHashMap, yous demand to modify your code. Here, nosotros are using Map interface for getting Employee object from Cache, which tin hold upward whatever valid Map implementation, including HashMap, Hashtable, or ConcurrentHashMap. On similar line, yous should role interface equally Type of method arguments in addition to equally render type. This makes your code flexible plenty to operate on whatever implementation.

Use Interface inwards Java to suit Design patterns

If yous are familiar of famous GOF blueprint patterns than yous know that almost of the behavioural pattern role Polymorphism for dynamic behaviour, e.g. Decorator pattern, implements same interface equally the object, which it decorates. If yous don't role interface, it would hold upward impossible to contain blueprint patterns e.g. if your method convey concrete type, rather than abstract type, in addition to thence yous tin non top anything else to them. You non solely lose flexibility but besides runtime behavior enrichment. Similarly, Composite pattern besides uses same interface equally object it contains, in addition to this allows caller to bargain amongst a normal object or composite object inwards same way, had they don't role interface, it wasn't possible. Proxy in addition to Adapter blueprint pattern besides relies on higher bird abstraction e.g. interface or abstract class, to render added behaviour. In short, interface is non only a skillful coding practice, it besides opened upward path to contain other best practices inwards your code.

Use Interface to assist Unit Testing

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


That's all on why yous should role interface inwards Java. Though yous tin non define concrete methods, it's best agency to innovate abstraction inwards your design. Real role of interface is to better code character past times allowing modules to depend upon higher bird of abstraction, which is less probable to modify than lower bird concrete classes, which is to a greater extent than probable to change. Use of interface besides opens opportunities for using tried in addition to tested Java blueprint pattern in addition to immensely helps inwards Unit testing equally well. Most importantly, role of interface volition laissez passer on yous dissimilar bird of thinking in addition to belike it's i mensuration inwards mastering object oriented analysis in addition to design.

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