Code:
int daysPassed = getDays(date1) - getDays(date2)
public int getDays(Date date) {
//Get the number of days that have passed since 1/1/1970 00:00:00 GMT
long millis = date.getTime();
double seconds = Math.floor(millis / 1000);
double minutes = Math.floor(seconds / 60);
double hours = Math.floor(minutes / 60);
double days = Math.floor(hours / 24);
return (int) days;
}