Android to detect when you are holding down a button

I need to be able to tell when the user is holding a button down and when the user lets go. This is different from onClickListener and onLongClickListener. How would i go about doing something like this?

For example I press a button that starts a chronometer.(pseudo code)

if ButtonIsBeingPressed
{
chronometer start(); //and keep going
}
else chronometer stop();
//or on release or something
}