Java Design Patterns Tutorial - Java Design Pattern - Adapter Pattern

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We use the adapter in real life a lot. For example, we use a memory card adapter to connect a memory card and a computer since the computer only support one type of memory card and our card is not compatible with the computer.

Adapter is a converter between two incompatible entities. Adapter pattern is a structural pattern.

In Java design pattern, Adapter pattern works as a bridge between two incompatible interfaces.

By using the adapter pattern we can unify the two incompatible interfaces.

Example

First we create a Player interface to play any time of media files.

MyPlayer is the adapter, it unifies the interface of playing media files.

interface Player {
   public void play(String type, String fileName);
}/*  www.jav  a  2  s .com*/
interface AudioPlayer {  
   public void playAudio(String fileName);
}
interface VideoPlayer {  
   public void playVideo(String fileName);
}
class MyAudioPlayer implements AudioPlayer {
   @Override
   public void playAudio(String fileName) {
      System.out.println("Playing. Name: "+ fileName);    
   }
}
class MyVideoPlayer implements VideoPlayer {
   @Override
   public void playVideo(String fileName) {
      System.out.println("Playing. Name: "+ fileName);    
   }
}

class MyPlayer implements Player {

   AudioPlayer audioPlayer = new MyAudioPlayer();
   VideoPlayer videoPlayer = new MyVideoPlayer();
   
   public MyPlayer(){      
   }
   @Override
   public void play(String audioType, String fileName) {
      if(audioType.equalsIgnoreCase("avi")){
         videoPlayer.playVideo(fileName);
      }else if(audioType.equalsIgnoreCase("mp3")){
         audioPlayer.playAudio(fileName);
      }
   }
}
public class Main{
   public static void main(String[] args) {
      MyPlayer myPlayer = new MyPlayer();

      myPlayer.play("mp3", "h.mp3");
      myPlayer.play("avi", "me.avi");
   }
}

The code above generates the following result.

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