Can you give an example of how the adapter pattern is used in software engineering?

The adapter pattern allows objects with incompatible interfaces to work together by converting the interface of one class into another interface expected by the client.

Example in Java: suppose we have an interface MediaPlayer with a method play(String audioType, String fileName), and a class AdvancedMediaPlayer with methods playVlc(String fileName) and playMp4(String fileName). To use AdvancedMediaPlayer through MediaPlayer, we create an adapter:

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

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

// Concrete implementations
class VlcPlayer implements AdvancedMediaPlayer {
    public void playVlc(String fileName) {
        System.out.println("Playing vlc file: " + fileName);
    }
    public void playMp4(String fileName) { }
}

class Mp4Player implements AdvancedMediaPlayer {
    public void playVlc(String fileName) { }
    public void playMp4(String fileName) {
        System.out.println("Playing mp4 file: " + fileName);
    }
}

// Adapter
class MediaAdapter implements MediaPlayer {
    AdvancedMediaPlayer advancedMusicPlayer;

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

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

// Client
class AudioPlayer implements MediaPlayer {
    MediaAdapter mediaAdapter;

    public void play(String audioType, String fileName) {
        if(audioType.equalsIgnoreCase("mp3")) {
            System.out.println("Playing mp3 file: " + fileName);
        } else if(audioType.equalsIgnoreCase("vlc") || audioType.equalsIgnoreCase("mp4")) {
            mediaAdapter = new MediaAdapter(audioType);
            mediaAdapter.play(audioType, fileName);
        } else {
            System.out.println("Invalid media type: " + audioType);
        }
    }
}

Thus, AudioPlayer uses MediaAdapter to play formats it doesn't directly support, ensuring interface compatibility.