1public interface IPlayerState
2{
3    void Play();
4    void Pause();
5    void Stop();
6}

1public class PlayState : IPlayerState
2{
3    public void Play()
4    {
5        Console.WriteLine("Music is already playing.");
6    }
7
8    public void Pause()
9    {
10        Console.WriteLine("Music paused.");
11    }
12
13    public void Stop()
14    {
15        Console.WriteLine("Music stopped.");
16    }
17}
18
19public class PauseState : IPlayerState
20{
21    public void Play()
22    {
23        Console.WriteLine("Music resumed.");
24    }
25
26    public void Pause()
27    {
28        Console.WriteLine("Music is already paused.");
29    }
30
31    public void Stop()
32    {
33        Console.WriteLine("Music stopped.");
34    }
35}
36
37public class StopState : IPlayerState
38{
39    public void Play()
40    {
41        Console.WriteLine("Music started playing.");
42    }
43
44    public void Pause()
45    {
46        Console.WriteLine("Music cannot be paused. It's stopped.");
47    }
48
49    public void Stop()
50    {
51        Console.WriteLine("Music is already stopped.");
52    }
53}

1public class MusicPlayer
2{
3    private IPlayerState _state;
4
5    public MusicPlayer()
6    {
7        // حالت اولیه پخش
8        _state = new PlayState();
9    }
10
11    public void SetState(IPlayerState state)
12    {
13        _state = state;
14    }
15
16    public void Play()
17    {
18        _state.Play();
19    }
20
21    public void Pause()
22    {
23        _state.Pause();
24    }
25
26    public void Stop()
27    {
28        _state.Stop();
29    }
30}

1public class Program
2{
3    public static void Main()
4    {
5        MusicPlayer player = new MusicPlayer();
6
7        // پخش موسیقی
8        player.Play();
9
10        // توقف موسیقی
11        player.Stop();
12
13        // مکث موسیقی
14        player.Pause();
15        
16        // پخش مجدد موسیقی
17        player.Play();
18    }
19}

Music is already playing.
Music stopped.
Music is already stopped.
Music paused.
Music resumed.