Introduction

Consider we are creating an audio player application. There may be a chance of creating noisy output on the speaker because another app uses the audio hardware at the same time. To reduce this, Android has a built-in API called AudioFocusRequest.
Step 1

We have to register for an audio listener, so that the listener class will provide the information whether another application is using the audio or not.
Step 2

Add the following code to the class where you're going to implement the listeners. We have to get the audio service using AudioManger.
  1. public bool RequestAudioFocus()
  2. {
  3. var amanager = (AudioManager)GetSystemService(AudioService);
  4. AudioFocusRequest audioFocusRequest;
  5. if (Build.VERSION.SdkInt > BuildVersionCodes.O)
  6. {
  7. audioFocusRequest = amanager.RequestAudioFocus(new AudioFocusRequestClass.Builder(AudioFocus.Gain)
  8. .SetAudioAttributes(new AudioAttributes.Builder().SetLegacyStreamType(Stream.Music).Build())
  9. .SetOnAudioFocusChangeListener(this)
  10. .Build());
  11. }
  12. else
  13. {
  14. audioFocusRequest = amanager.RequestAudioFocus(this, Stream.Music, AudioFocus.Gain);
  15. }
  17. if (audioFocusRequest == AudioFocusRequest.Granted)
  18. {
  19. return true;
  20. }
  21. return false;
  22. }
Step 3

Implement the interface "AudioManager.IOnAudioFocusChangeListener" which implements a method called.

OnAudioFocusChange.
  1. public void OnAudioFocusChange([GeneratedEnum] AudioFocus focusChange)
  2. {
  3. }
Step 4

Inside "OnAudioFocusChange" Method implement the switch case to handle the audio Focus.
  1. switch (focusChange)
  2. {
  3. case AudioFocus.Gain:
  5. //Gain when other Music Player app releases the audio service
  7. }
  8. break;
  9. case AudioFocus.Loss:
  10. //We have lost focus stop!
  12. break;
  13. case AudioFocus.LossTransient:
  14. //We have lost focus for a short time, but likely to resume so pause
  16. break;
  17. case AudioFocus.LossTransientCanDuck:
  18. //We have lost focus but should till play at a muted 10% volume
  20. break;
  21. }
Step 5

The final implemetation will be like below.
  1. public class AudioFocus : AudioManager.IOnAudioFocusChangeListener
  2. {
  3. public AudioFocus()
  4. {
  5. RequestAudioFocus();
  6. }
  7. public bool RequestAudioFocus()
  8. {
  9. audioManager = (AudioManager)GetSystemService(AudioService);
  10. AudioFocusRequest audioFocusRequest;
  11. if (Build.VERSION.SdkInt > BuildVersionCodes.O)
  12. {
  13. audioFocusRequest = audioManager.RequestAudioFocus(new AudioFocusRequestClass.Builder(AudioFocus.Gain)
  14. .SetAudioAttributes(new AudioAttributes.Builder().SetLegacyStreamType(Stream.Music).Build()) .SetOnAudioFocusChangeListener(this)
  15. .Build());
  16. }
  17. else
  18. {
  19. audioFocusRequest = audioManager.RequestAudioFocus(this, Stream.Music, AudioFocus.Gain);
  20. }
  22. if (audioFocusRequest == AudioFocusRequest.Granted)
  23. {
  24. return true;
  25. }
  26. return false;
  27. }
  29. public void OnAudioFocusChange([GeneratedEnum] AudioFocus focusChange)
  30. {
  31. switch (focusChange)
  32. {
  33. case AudioFocus.Gain:
  35. //Gain when other Music Player app releases the audio service
  36. break;
  37. case AudioFocus.Loss:
  38. //We have lost focus stop!
  40. break;
  41. case AudioFocus.LossTransient:
  42. //We have lost focus for a short time, but likely to resume so pause
  44. break;
  45. case AudioFocus.LossTransientCanDuck:
  46. //We have lost focus but should till play at a muted 10% volume
  48. break;
  49. }
  50. }
  51. }
At last, remember to release the audio service.