By using AudioManager  you can get current volume level and max volume level. At the time of button click/ option select you can control the volume level also. Here is the code.I hope this will help you to set volume.
AudioManager audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
int curVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
To Set Volume 
audioManager.setStreamVolume(AudioManager.STREAM_MUSIC,vol_level, 0);