问题
Android has the Hardware button for controlling volume (increase/decrease). I want to same functionality by using buttons in my application with visual volume control and it should be disappeared after some time (in sec).
回答1:
You need to use the AudioManager class. Developer doc is here. Depending on which volume you want to adjust (ringer/media) you may need to change the audiomode via AudioManager.
Finally, to make the buttons disappear just use View.GONE on them. I would create a Runnable in the onClickListener and use a postDelayed to make the View disappear.
来源：https://stackoverflow.com/questions/5117051/how-to-control-volume-in-android