Structural Patterns - Adapter Pattern

Adapter pattern works as a bridge between two incompatible interfaces. This type of design pattern comes under structural pattern as this pattern combines the capability of two independent interfaces.

Step 1

Create interfaces for Media Player and Advanced Media Player.

MediaPlayer.cs

public interface MediaPlayer {
   void play(String audioType, String fileName);
}

AdvancedMediaPlayer.cs

public interface AdvancedMediaPlayer { 
   void playVlc(String fileName);
   void playMp4(String fileName);
}

Step 2

Create concrete classes implementing the AdvancedMediaPlayer interface.

VlcPlayer.cs

public class VlcPlayer implements AdvancedMediaPlayer{
   @Override
   public void playVlc(String fileName) {
      Console.Write("Playing vlc file. Name: "+ fileName);  
   }

   @Override
   public void playMp4(String fileName) {
      //do nothing
   }
}

Mp4Player.cs

public class Mp4Player implements AdvancedMediaPlayer{

   @Override
   public void playVlc(String fileName) {
      //do nothing
   }

   @Override
   public void playMp4(String fileName) {
      Console.Write("Playing mp4 file. Name: "+ fileName);  
   }
}

Step 3

Create adapter class implementing the MediaPlayer interface.

MediaAdapter.cs

public class MediaAdapter implements MediaPlayer {

   AdvancedMediaPlayer advancedMusicPlayer;

   public MediaAdapter(String audioType){
   
      if(audioType.contains("vlc") ){
         advancedMusicPlayer = new VlcPlayer();   
         
      }else if (audioType.contains("mp4")){
         advancedMusicPlayer = new Mp4Player();
      } 
   }

   @Override
   public void play(String audioType, String fileName) {
   
      if(audioType.contains("vlc")){
         advancedMusicPlayer.playVlc(fileName);
      }
      else if(audioType.contains("mp4")){
         advancedMusicPlayer.playMp4(fileName);
      }
   }
}

Step 4

Create concrete class implementing the MediaPlayer interface.

AudioPlayer.cs

public class AudioPlayer implements MediaPlayer {
   MediaAdapter mediaAdapter; 

   @Override
   public void play(String audioType, String fileName) {  

      //inbuilt support to play mp3 music files
      if(audioType.contains("mp3")){
         System.out.println("Playing mp3 file. Name: " + fileName);   
      } 
      
      //mediaAdapter is providing support to play other file formats
      else if(audioType.contains("vlc") || audioType.contains("mp4")){
         mediaAdapter = new MediaAdapter(audioType);
         mediaAdapter.play(audioType, fileName);
      }
      
      else{
         Console.Write("Invalid media. " + audioType + " format not supported");
      }
   }   
}

Step 5

Use the AudioPlayer to play different types of audio formats.

Client.cs

public class AdapterPatternDemo {
   public static void main(String[] args) {
      AudioPlayer audioPlayer = new AudioPlayer();

      audioPlayer.play("mp3", "beyond the horizon.mp3");
      audioPlayer.play("mp4", "alone.mp4");
      audioPlayer.play("vlc", "far far away.vlc");
      audioPlayer.play("avi", "mind me.avi");
   }
}

Step 6

Verify the output.

Playing mp3 file. Name: beyond the horizon.mp3
Playing mp4 file. Name: alone.mp4
Playing vlc file. Name: far far away.vlc
Invalid media. avi format not supported