Cheesy quick way of doing it is to subtract their time values from each other.
You can then work out number of hours by dividing by (60x60x1000) and days in a similar way.
long difference = date2.getTime() - date1.getTime();
int days = difference / (24 * 60 * 60 * 1000);
difference -= days * (24 * 60 * 60 * 1000);
int hours = difference / (60 * 60 * 1000);
It should suffice.