First of all you have to get it clear how to interpret a Double value as Date. E.g. in Oracle and Excel the represents the integer part the days and the fraction the time. Of course the routine do you mentioned cannot do this because it expects a date formatted String, this is not what you have provided!
Here is an example of a routine which converts a Double into a Date:
public static Date getDuration(Double timeInExcel) {
if (timeInExcel != null) {
int wholeDays = (int) Math.floor(timeInExcel);
int millisecondsInDay = (int) ((timeInExcel - wholeDays) * DAY_MILLISECONDS + 0.5);
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(0);
cal.set(Calendar.DAY_OF_YEAR, wholeDays + 1);
cal.set(Calendar.MILLISECOND, millisecondsInDay);
return cal.getTime();
} else {
return null;
}
}
This is a simple approach and I do not know in which way your Double value have to be interpreted as Date. This is the first question you have to ask!
