Adapter Pattern Pattern Inwards Coffee Amongst Example

Adapter pattern pattern inward Java, too known every bit the Wrapper pattern is some other really useful GOF pattern, which helps to span the gap betwixt ii classes inward Java. As per the listing of Gang of Four patterns, Adapter is a structural pattern, much similar Proxy, Flyweight, Facade, in addition to Decorator pattern inward Java. As the mention suggest, Adapter allows ii classes of a unlike interface to piece of work together, without changing whatever code on either side. You tin sentiment Adapter pattern is a key slice of the puzzle, which joins ii pieces, which tin non hold out direct joined because of unlike interfaces. I come across a distich of reference of Adapter pattern pattern inward i of my favorite majority Clean Code, but the thought is really good explained inward Head First Design Pattern, the icon which they present to illustrate Adapter pattern pattern is worth all the talk.

By the way, Adapters are everywhere inward existent life, most usually when nosotros verbalize almost Adapter, nosotros hateful electrical adapters. If you lot direct keep got an onsite chance in addition to had visited US, United Kingdom of Great Britain in addition to Northern Ireland of Britain in addition to Northern Republic of Ireland or whatever other Europian or North American country, you lot mightiness direct keep seen unlike kinds of  electrical socket than inward Republic of Republic of India e.g. USA has a rectangular socket, every bit compared to cylindrical i from India. Basically, when nosotros verbalize Electrical adapter, nosotros talked almost adapter which changes the voltage or the one's which allows using a plug designed for i reason inward a Socket of some other country.

This illustration shows an of import attribute of Adapter pattern pattern inward software development, you lot tin neither modify the Socket of visiting country, neither tin modify the plug of your  laptop, So you lot innovate an Adapter, which makes things working without changing whatever party. Similarly, Adapter pattern pattern makes incompatible interfaces piece of work together, without changing them. Only novel code which is inserted is inward the shape of Adapter or Wrapper class.

How to implement Adapter Design pattern inward Java

There are ii ways to implement Adapter pattern pattern inward Java, i using Inheritance too known every bit Class Adapter pattern in addition to other is using Composition, ameliorate known every bit Object Adapter pattern. In both cases, it's ameliorate to declare customer interacting populace methods inward an interface, you lot may telephone telephone it target interface.

One payoff of using target interface to roll customer facing method inward an Adapter, you lot create a loosely coupled design, where you lot tin supplant your Adapter amongst ameliorate implementation inward the afterward phase of development.

Now your Class Adapter pattern extends the original interface, which is incompatible to the customer but provides the functionality needed yesteryear the client, in addition to it too implements the target interface. Now, Adapter implements target method inward such a agency that it delegates actual piece of work on original class, which Adapter acquire access yesteryear extending it.

Similarly, inward the instance of Object Adapter pattern, which uses Composition for reusing code, it too implements target interface in addition to uses object of the Original incompatible course of written report to practise all of its work. Since It's ameliorate to prefer composition over inheritance, I advise that you lot should stick amongst Object Adapter pattern.

hither is a UML diagram of Adapter pattern pattern which volition brand things easier to sympathise in addition to too clear whatever dubiety you lot direct keep almost the construction of this pattern:

In  this example, Client is a target interface in addition to Wizard is the Adaptee. In social club to facilitate the occupation of Wizard, nosotros direct keep created WizardAdapter which implements target interface Fighter but delegates piece of work to Adaptee.

Adapter pattern inward Java - Map Adapter

Let's come across i to a greater extent than illustration of Adapter pattern inward Java. If you lot recollect the java.util.Map has no agency to automatically charge a two-dimensional array of objects into a Map every bit key-value pairs. We tin create an adapter course of written report that does this.

Sometimes the job you lot are solving is every bit uncomplicated every bit "I don't direct keep the interface I want". Two of the patterns inward the listing of GOF pattern patterns, Adapter, in addition to Facade pattern solve this job yesteryear providing an alternate interface. Adapter pattern takes whatever interface you lot direct keep in addition to hit the interface you lot need. While Facade pattern provides a simpler interface to bargain amongst a let on of classes or packet of resources.

Here is my implementation of Adapter pattern inward Java to convert a two-dimensional array of objects into Map of key-value pairs


Java Program to implement Adapter pattern Pattern

import java.util.AbstractMap; import java.util.HashMap; import java.util.Map; import java.util.Set;  /**  * Implementation of Adapter pattern inward Java. The java.util.Map has no agency to  * automatically charge a ii dimensional array of objects into a Map every bit key-value  * pairs. This Java programme creates an adapter course of written report that does this.  *   * @author WINDOWS 8  */  public class Test {      public static void main(String args[]) {                  Integer[][] squares = { {2, 4}, {3, 9}, {4, 16}};          MapAdapter adapter = new MapAdapter(squares);                  System.out.println("adapter map contains : " + adapter);     }  }  /*  * This course of written report is an adapter which allows to create a Map yesteryear providing a ii  * dimensional array of keys in addition to values. It extends AbstractMap course of written report in addition to then that it  * decease a Map in addition to tin hold out passed precisely about where a Map is needed. All other method  * is implemented inward AbstractMap except the adapter functionality which is  * implemented inward constructor of this class.  */ class MapAdapter extends AbstractMap {     private Map map;      public MapAdapter(Object[][] array) {         super();         map = new HashMap();         for(Object[] mapping : array){             map.put(mapping[0], mapping[1]);         }      }      @Override     public Set entrySet() {         return map.entrySet();     }  }   Output adapter map contains : {2=4, 3=9, 4=16}

You tin come across that our MapAdapter extends AbstractMap to create a Map which tin accept a two-dimensional array in addition to create a HashMap from that.

Here is i to a greater extent than interesting diagram which volition assist you lot to sympathise the intent in addition to purpose of Adapter pattern inward Java. You tin come across that your existing organisation in addition to vendor course of written report doesn't jibe initially but when you lot add together an Adapter the puzzle is solved in addition to both systems is able to plugged together.

Important points almost Adapter Pattern inward Java

1) Adapter pattern pattern ensures code reusability for delegating calls from the customer to original class, i.e. it human activeness similar a wrapper of original interface, that's why it's too called wrapper pattern or precisely a wrapper. This is genuinely the original practise goodness of using Adapter pattern.


2) Adapter pattern is a full general purpose pattern, much similar Singleton, Factory, in addition to Decorator in addition to you lot volition come across a lot of examples of Adapter pattern through the code, i of the key benefits of using Adapter pattern inward Java is reusing code, making incompatible interfaces piece of work together in addition to release coupling because Adapter tends to encapsulate incompatible interface quite well.


3) One of the cases where you lot desire to occupation Adapter pattern pattern inward Java programme is spell using a third-party library. By making sure, your programme uses Adapter, which is inward your control, rather than direct using third-party interface in addition to classes, you lot tin anytime supplant third-party library, amongst similar, ameliorate performing API. You tin count this i of the pros of using Adapter pattern.


4) In the Gang of Four pattern patterns, Adapter pattern is constituent of structural pattern pattern along amongst Proxy, Facade, in addition to Decorator pattern pattern.


5) Influenza A virus subtype H5N1 lot of programmers confuse betwixt Adapter in addition to Decorator pattern pattern inward Java, to some extent they are similar, particularly object based adapter pattern but at that spot is a subtle divergence betwixt Decorator in addition to Adapter pattern inward Java. Adapter precisely converts i interface to another, without adding additional functionalities, spell Decorator adds novel functionality into an interface. See here to acquire to a greater extent than almost the divergence betwixt Adapter in addition to Decorator pattern inward Java.


6) You tin too occupation Adapter pattern pattern inward Java for conversion classes, e.g. Suppose your customer practise all calculation inward Miles in addition to the library you lot are using expects Kilometers. In this case, you lot tin write an Adapter class, which takes miles from Client, converts it to Kilometer in addition to leverages external library methods for all calculation. While returning a result, it tin convert KM dorsum to miles in addition to mail the outcome to Client.


7) Prefer Object-based Adapter pattern pattern than Class based, because old uses Composition for code re-use in addition to to a greater extent than flexible than Inheritance based approach of Class based Adapter pattern inward Java.


That's all on What is Adapter pattern pattern inward Java, How in addition to when to occupation Adapter pattern in addition to divergence betwixt Class in addition to Object based implementation of Adapter pattern pattern. The adapter is genuinely useful full general purpose pattern in addition to Java developers should accept payoff of this pattern every bit much every bit possible to write flexible code.

Other Java pattern pattern tutorials you lot may like

• What is the divergence betwixt State in addition to Strategy pattern inward Java? (answer)
• How to implement Strategy pattern inward Java? (example)
• How to pattern a Vending Machine inward Java?  (solution)
• What is the divergence betwixt Factory in addition to AbstractFactory pattern inward Java? (answer)
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• What is the divergence betwixt Factory pattern in addition to Dependency injection? (solution)
• How to implement Command pattern pattern inward Java? (solution)
• How to implement Data Access Object Pattern inward Java? (solution)
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Further Learning
Design Pattern Library
From 0 to 1: Design Patterns - 24 That Matter - In Java
Java Design Patterns - The Complete Masterclass

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