如何检测Android上按下和释放按钮的时间

I would like to start a timer that begins when a button is first pressed and ends when it is released (basically I want to measure how long a button is held down). I'll be using the System.nanoTime() method at both of those times, then subtract the initial number from the final one to get a measurement for the time elapsed while the button was held down.I would like to start a timer that begins when