The following code, placed on onResume() of a Home Screen replacement activity, allows you to run a block of code when Home is tapped twice in succession. int detectDoubleTap = 0; // Define this either as a static variable in external class or else in the onCreate() and make variable global
if (System.currentTimeMillis() - detectDoubleTap < 250) {
// Code to be run on double tap
}
detectDoubleTap = System.currentTimeMillis();
While this works fine, it doesn't seem (to answer my question) that there is any way to forcibly override whatever the user has set up as the Double Tap Launch App. So if there is an app that is launched on double tap, the code above will run, AND the app will launch.