CODEWITHSUNDEEP
javasimpledateformatdatetime-parsing
Diane Kaplan
Diane Kaplan

Reputation: 1708

SimpleDateFormat parsing issue for dateFormat using milliseconds

I'm working on migrating some data (in java) where I'm pulling date strings from several different sources (that use different formats) and I need to send them along in a consistent format. So I have a method that takes a string (and the source it came from so I know which format to use) and converts it into a date, so I can go from there.

Problem: all of the formats work perfectly except for the first one: the resulting date values returned are between 0-17 minutes off from the original string I give it!

// Take a string, convert to a date
public static Date convertStringToDate (String dateString, String source) {
    String dateFormat = null;
    switch (source)
    {
        case "DATA": //@FIXME: these vary 0-17 minutes off!
            dateFormat = "yyyy-MM-dd HH:mm:ss.SSSSSS"; // 2018-08-29 20:09:26.863631 (ex: mailing list records)
            break;
        case "DATA_EN": // encrypted dates use a different format
            dateFormat = "yyyy-MM-dd HH:mm:ss ZZZZ"; // 2019-06-12 14:33:27 +0000 (ex: encrypted_patient_information_complete_at)
            break;
        case "DatStat":
            dateFormat = "yyyy-MM-dd'T'HH:mm:ss'Z'"; // 2018-08-29T14:33:49Z (ex: followup survey)
            break;
        case "download":
            if (dateString.length() > 10 ){ // the majority of these will be in format 1/9/16 9:30
                dateFormat = "M/dd/yy HH:mm"; // 2/16/18 19:58 (ex: csv from datstat)
            } else { // dates submitted at midnight lose their time and have format 9-Jan-16
                dateFormat = "dd-MMM-yy"; // 9-Jan-16
            }
            break;
        default:
            dateFormat = "INVALID SOURCE VALUE GIVEN";
            break;
    }

    SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
    Date dt = null;
    try {
        dt = sdf.parse(dateString);
    }
    catch (Exception ex) {
        throw new RuntimeException("An error has occurred trying to parse timestamp." + dateString, ex);
    }
    return dt;
}

Example input/output:

I'm wondering if there's something particular to this format that I'm not getting right, but haven't found anything in reading around. Does anyone see what the issue could be? Or have you seen this before?

Upvotes: 1

Views: 1044

Answers (1)

Asoub
Asoub

Reputation: 2371

As Other have mentionned in comment, other thread answers this well: https://stackoverflow.com/a/6157860/5190019

The fact is that SSSSSS doesn't exist as a format for this class, it expects only 3 number for milliseconds. So it is interpreted as such. DateFormat will interpret 712754 as 712754/1000 seconds rather than 0.712754 seconds. And if you do the calculus it's 11,86. minutes, which mean 11mn52 seconds. So 33:08+11:52, is 45:00, the result you get.

As for the solution, you can either strip the rest of the milliseconds part because you don't need it anyway (as you did) or use another class (all comments from Ole V.V are on point).

Upvotes: 1

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