title: Is there a listener to listen for changes in the volume in android?
body: <p>Is it possible to register a listener to listen for changes in the volume level of the music stream in Android?</p>
  
  <p>I'm displaying the actual volume in a SeekBar and I would like to change the seekbar if the user changes the volume with the hardware volume keys. At the moment the correct volume is displayed until the user changes the volume with hardware keys.</p>