Parsing Java dates with truncated timezone information

Question

Consider the following date string

2012-10-01 01:02:03.004+0500

This is recognized in Java using the following SimpleDateFormat pattern:

yyyy-MM-dd HH:mm:ss.SSSZ

If, however, the timezone information above is truncated to 2 digits, i.e. like

2012-10-01 01:02:03.004+05

the date string does not comply to any valid format, so there is no SimpleDateFormat pattern that could be used in order to correctly parse it.

Is there any workaround for parsing the truncated timezone correctly without string preprocessing?

If not, which regular expression would be optimal for that preprocessing to be done for a large number of such date strings in 1 round, e.g. using a replaceFirst() call, as in this similar question?

That's a SimpleDateFormatpattern, not a DateFormat pattern. Try subclassing SimpleDateFormat to append 00 when needed. — Christoffer Hammarström
– Christoffer Hammarström, Commented Oct 18, 2012 at 10:06
You are right in both suggestions. The subclassing approach seems the most plausible at this point, along the lines of the similar question I linked to above. — PNS
– PNS, Commented Oct 18, 2012 at 10:26

Sergey Kalinichenko · Accepted Answer · 2012-10-18 10:02:27Z

2

I do not know a good solution without string preprocessing, but if replaceFirst is acceptable, you can use this code snippet:

dateStr.replaceFirst("(?<=[+-]\\d\\d)$", "00")

This code appends two zeros to strings ending in <plus|minus><digit><digit> (link to ideone).

answered Oct 18, 2012 at 10:02

Sergey Kalinichenko

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4 Comments

Christoffer Hammarström Over a year ago

The timezone can start with a <minus> too.

PNS Over a year ago

I was thinking of something like that, but I am concerned about performance. You are right in that there seems to be no ideal solution. Your proposal does work. You may want to change \\d\\d into \\d{2}, for elegance. Thanks! :-)

Sergey Kalinichenko Over a year ago

@PNS On the point of \\d{2}, programmers often count "zero, one, two, many", and I'm one of them. Besides, there may only be so much "elegance" when we are talking regular expressions ;-)

PNS Over a year ago

I prefer elegance, but no worries. It will do just fine! :-)

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