我我刚刚在SDK 8（Android 2.2）上测试了以下代码片段：

I've just tested on SDK 8 (Android 2.2) the following code snippet:

Calendar date1 = Calendar.getInstance();
Calendar date2 = Calendar.getInstance();

date1.clear();
date1.set(
   datePicker1.getYear(),
   datePicker1.getMonth(),
   datePicker1.getDayOfMonth());
date2.clear();
date2.set(
   datePicker2.getYear(),
   datePicker2.getMonth(),
   datePicker2.getDayOfMonth());

long diff = date2.getTimeInMillis() - date1.getTimeInMillis();

float dayCount = (float) diff / (24 * 60 * 60 * 1000);

textView.setText(Long.toString(diff) + " " + (int) dayCount);

13,2011 - 2011年11月11日）给出了 dayCount = 2.0

it works perfectly and in both cases (Nov 10,2011 - Nov 8,2011) and (Nov 13,2011 - Nov 11,2011) gives dayCount = 2.0