Parsing time strings like "1h 30min"

Anyone know of a Java library that can parse time strings such as "30min" or "2h 15min" or "2d 15h 30min" as milliseconds (or some kind of Duration object). Can Joda-Time do something like this?

(I have an ugly long method to maintain that does such parsing and would like to get rid of it / replace it with something that does a better job.)

Solution 1:

You'll probably have to tweak this a bit for your own format, but try something along these lines:

PeriodFormatter formatter = new PeriodFormatterBuilder()
    .appendDays().appendSuffix("d ")
    .appendHours().appendSuffix("h ")
    .appendMinutes().appendSuffix("min")
    .toFormatter();

Period p = formatter.parsePeriod("2d 5h 30min");

note that there is a appendSuffix that takes a variants parameter if you need to make it more flexible.

Update: Joda Time has since added Period.toStandardDuration(), and from there you can use getStandardSeconds() to get the elapsed time in seconds as a long.

If you're using an older version without these methods you can still calculate a timestamp yourself by assuming the standard 24/hr in a day, 60min/hr, etc. (In this case, take advantage of the constants in the DateTimeConstants class to avoid the need for magic numbers.)

Solution 2:

Duration parsing is now included in Java 8. Use standard ISO 8601 format with Duration.parse.

Duration d = Duration.parse("PT1H30M")

You can convert this duration to the total length in milliseconds. Beware that Duration has a resolution of nanoseconds, so you may have data loss going from nanoseconds to milliseconds.

long milliseconds = d.toMillis();

The format is slightly different than what you describe but could be easily translated from one to another.

Solution 3:

I wanted to make the day, hour and minute optional and this seems to work to do that. Note that the appendSuffix() calls do not have a space after the character.

Using Joda 2.3.

PeriodParser parser = new PeriodFormatterBuilder()
        .appendDays().appendSuffix("d").appendSeparatorIfFieldsAfter(" ")
        .appendHours().appendSuffix("h").appendSeparatorIfFieldsAfter(" ")
        .appendMinutes().appendSuffix("min")
        .toParser();

The above code passes these tests.

@Test
public void testConvert() {
    DurationConverter c = new DurationConverter();

    Duration d;
    Duration expected;

    d = c.convert("1d");
    expected = Duration.ZERO
            .withDurationAdded(Duration.standardDays(1),1);
    assertEquals(d, expected);

    d = c.convert("1d 1h 1min");
    expected = Duration.ZERO
            .withDurationAdded(Duration.standardDays(1),1)
            .withDurationAdded(Duration.standardHours(1),1)
            .withDurationAdded(Duration.standardMinutes(1),1);
    assertEquals(d, expected);


    d = c.convert("1h 1min");
    expected = Duration.ZERO
            .withDurationAdded(Duration.standardHours(1),1)
            .withDurationAdded(Duration.standardMinutes(1),1);
    assertEquals(d, expected);

    d = c.convert("1h");
    expected = Duration.ZERO
            .withDurationAdded(Duration.standardHours(1),1);
    assertEquals(d, expected);

    d = c.convert("1min");
    expected = Duration.ZERO
            .withDurationAdded(Duration.standardMinutes(1),1);
    assertEquals(d, expected);

}