Question

Background:

In my database table, I have two timestamps

timeStamp1 = 2011-08-23 14:57:26.662
timeStamp2 = 2011-08-23 14:57:26.9

When I do an “ORDER BY TIMESTAMP ASC”, timeStamp2 is considered as the greater timestamp(which is correct).

Requirement: I need to get the difference of these timestamps (timeStamp2 – timeStamp1)

My implementation:

public static String timeDifference(String now, String prev) {
    try {
        final Date currentParsed = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").parse(now);
        final Date previousParsed = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").parse(prev);
        long difference = currentParsed.getTime() - previousParsed.getTime();
        return "" + difference;
    } catch (ParseException e) {
        return "Unknown";
    }
}

The answer should have been 238ms, but the value that is returned is -653ms.
I’m not sure what I’m doing wrong. Any suggestions?

Answer 1

I’m not entirely sure, but the JavaDoc states this:

For parsing, the number of pattern letters is ignored unless it’s needed to separate two adjacent fields.

This indicates that the milliseconds from 2011-08-23 14:57:26.9 would be parsed as 9 instead of 900. Adding the trailing zeros might work: 2011-08-23 14:57:26.900.