Adapter

1// Target interface - what client expects
2interface MediaPlayer {
3    void play(String filename);
4}
5
6// Adaptee - existing class with incompatible interface
7class AdvancedVideoPlayer {
8    public void playMp4(String filename) {
9        System.out.println("Playing MP4: " + filename);
10    }
11    
12    public void playVlc(String filename) {
13        System.out.println("Playing VLC: " + filename);
14    }
15}
16
17// Another Adaptee
18class ThirdPartyAudioPlayer {
19    public void playAudio(String file, String format) {
20        System.out.println("Playing " + format + " audio: " + file);
21    }
22}
23
24// Adapter - makes AdvancedVideoPlayer compatible with MediaPlayer
25class VideoAdapter implements MediaPlayer {
26    private AdvancedVideoPlayer videoPlayer;
27    
28    public VideoAdapter() {
29        this.videoPlayer = new AdvancedVideoPlayer();
30    }
31    
32    @Override
33    public void play(String filename) {
34        if (filename.endsWith(".mp4")) {
35            videoPlayer.playMp4(filename);
36        } else if (filename.endsWith(".vlc")) {
37            videoPlayer.playVlc(filename);
38        }
39    }
40}
41
42// Adapter for third-party audio player
43class AudioAdapter implements MediaPlayer {
44    private ThirdPartyAudioPlayer audioPlayer;
45    
46    public AudioAdapter() {
47        this.audioPlayer = new ThirdPartyAudioPlayer();
48    }
49    
50    @Override
51    public void play(String filename) {
52        String format = filename.substring(filename.lastIndexOf('.') + 1);
53        audioPlayer.playAudio(filename, format);
54    }
55}
56
57// Client
58class UniversalPlayer implements MediaPlayer {
59    private MediaPlayer mp3Player;
60    private VideoAdapter videoAdapter;
61    private AudioAdapter audioAdapter;
62    
63    public UniversalPlayer() {
64        this.videoAdapter = new VideoAdapter();
65        this.audioAdapter = new AudioAdapter();
66    }
67    
68    @Override
69    public void play(String filename) {
70        if (filename.endsWith(".mp3")) {
71            System.out.println("Playing MP3: " + filename);
72        } else if (filename.endsWith(".mp4") || filename.endsWith(".vlc")) {
73            videoAdapter.play(filename);
74        } else {
75            audioAdapter.play(filename);
76        }
77    }
78}
79
80// Usage
81public class Main {
82    public static void main(String[] args) {
83        MediaPlayer player = new UniversalPlayer();
84        
85        player.play("song.mp3");     // Built-in
86        player.play("movie.mp4");    // Via VideoAdapter
87        player.play("clip.vlc");     // Via VideoAdapter
88        player.play("track.wav");    // Via AudioAdapter
89    }
90}