NumberFormatException while parsing date with SimpleDateFormat.parse()

Joda-Time

FYI, the Joda-Time 2.3 library provides a class expressly for your purpose, time-only, without any date: LocalTime. And, it is thread-safe (immutable instances). Seems a much better option than manhandling the troublesome java.util.Date class.

LocalTime localTime = new LocalTime();

Dump to console…

System.out.println( "localTime: " + localTime );

When run…

localTime: 16:26:28.065

java.time

Java 8 brings the new java.time package, inspired by Joda-Time, defined by JSR 310.

In java.time, you will find a LocalTime class similar to the one in Joda-Time.

The likely cause is the fact that SimpleDateFormat isn't threadsafe, and you're referencing it from multiple threads. While extremely difficult to prove (and about as hard to test for), there is some evidence this is the case:

1. .11331133EE22 - notice how everything is doubled
2. 880044E.3880044E3 - same here

You probably have at least two threads interleaving. The E was throwing me, I was thinking it was attempting to deal with scientific notation (1E10, etc), but it's likely part of the time zone.

Thankfully, the (formatting) basic fix is simple:

private static final String FORMAT_STRING = "HH:mm:ss.SSSZ";    

public static Date getCurrentTimeOnly() {

    SimpleDateFormat formatter = new SimpleDateFormat(FORMAT_STRING);

    String onlyTimeStr = formatter.format(new Date());
    return formatter.parse(onlyTimeStr);
}

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There's a couple of other things you could be doing here, too, with a few caveats:

1 - If the timezone is UTC (or any without DST), this is trivial

public static Date getCurrentTimeOnly() {

    Date time = new Date();

    time.setTime(time.getTime() % (24 * 60 * 60 * 1000));

    return time;
}

2 - You're going to have trouble testing this method, because you can't safely pause the clock (you can change the timezone/locale). For a better time dealing with date/time in Java, use something like JodaTime. Note that LocalTime doesn't have a timezone attached, but Date only returns an offset in integer hours (and there are zones not on the hour); for safety, you need to either return a Calendar (with the full timezone), or just return something without it:

// This method is now more testable.  Note this is only safe for non-DST zones
public static Calendar getCurrentTimeOnly() {

    Calendar cal = new Calendar();

    // DateTimeUtils is part of JodaTime, and is a class allowing you to pause time!
    cal.setTimeInMillis(DateTimeUtils.currentTimeMillis() % (24 * 60 * 60 * 1000));

    return cal;
}