Processing Java Strings and Dates

Question

I need to process a list of Strings which may or may not be times. When I do receive a time, it will need to be converted from "HH:mm:ss" to number of milliseconds before processing:

final String unknownString = getPossibleTime();    

final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
dateFormat.setLenient(false);
try {
    final Date date = dateFormat.parse(unknownString);
    //date.getTime() is NOT what I want here, since date is set to Jan 1 1970

    final Calendar time = GregorianCalendar.getInstance();
    time.setTime(date);

    final Calendar calendar = GregorianCalendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, time.get(Calendar.HOUR_OF_DAY));
    calendar.set(Calendar.MINUTE, time.get(Calendar.MINUTE));
    calendar.set(Calendar.SECOND, time.get(Calendar.SECOND));

    final long millis = calendar.getTimeInMillis();
    processString(String.valueOf(millis));
}
catch (ParseException e) {
    processString(unknownString);
}

This code works, but I really dislike it. The exception handling is particularly ugly. Is there a better way to accomplish this without using a library like Joda-Time?

Hmm, wouldn't this be more suited for [codereview](http://codereview.stackexchange.com)? — fge, Jun 12 '13 at 14:38
maybe avoiding using the calendar? http://docs.oracle.com/javase/6/docs/api/java/util/Date.html#getTime() — fGo, Jun 12 '13 at 14:40
on date there is a method getTime(); this should return your final long millis if I got it right — user1121883, Jun 12 '13 at 14:41
@fGo How can I make sure the date is set to today and not Jan 1 1970 with only one Calendar? Its possible with the deprecated Date getters (getHours(), getMinutes(), getSeconds()), but I would prefer not using deprecated methods. — dbyrne, Jun 12 '13 at 14:44

John Strickler · Accepted Answer · 2013-06-13T12:29:47.283

2

public static long getTimeInMilliseconds(String unknownString) throws ParseException {

   DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
   String dateString = dateFormat.format(Calendar.getInstance().getTime());

   DateFormat timeFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
   return timeFormat.parse(dateString + " " + unknownString).getTime();
}

Handle the ParseException outside of this method however you'd like. I.e. ("No time information provided"... or "unknown time format"... etc.)

.getTime() returns the time in milliseconds. It's part of the java.util.Date API.

edited Jun 13 '13 at 12:29

answered Jun 12 '13 at 14:42

John Strickler

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The problem is that `date` is set to Jan 1 1970, not the current day. I'll update the code above with a comment to make that more clear. – dbyrne Jun 12 '13 at 14:46
@dbryne Good catch - I tried something a bit different. Check again. – John Strickler Jun 12 '13 at 14:56
[SimpleDateFormat is not threadsafe](http://stackoverflow.com/questions/6840803) so using static instances carries risk. – McDowell Jun 12 '13 at 21:04
@McDowell Thanks, I didn't know that but it makes sense. – John Strickler Jun 13 '13 at 12:30

score 1 · Answer 2 · answered Jun 12 '13 at 14:42

1

Why don't you first check if the input is actually of HH:mm:ss format. You can do this by trying match input to regex [0-9]?[0-9]:[0-9]?[0-9]:[0-9]?[0-9] first and if it matches then treat it as date otherwise call processString(unknownString);

answered Jun 12 '13 at 14:42

Saurabh

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`(\d|[01]\d|2[0-3]):([0-5]\d):([0-5]\d)` so you don't allow 30:73:99 as a valid time. – Eric Jablow Jun 12 '13 at 21:25

Processing Java Strings and Dates

2 Answers2