How to store time spent or total duration in Java?

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I am automating a excel report using the POI API for Java. I will have few reports in my disposal which I read using POI, process them, and create a new excel report.

One of columns from an excel file has total time spent, that is, it could in following format, 46:23:12 - this reads as 46 hours, 23 minutes and 12 seconds.

I understand how to read date and time values and I usually store them in java.util.Date. The problem here is this is a time duration, the hours spent could be more than 24. Which datatype could be suitable for this? And how do I read this using POI?

duration apache-poi time java
4 Answers

The accepted answer is correct and meets the requirements completely. This answer provides some additional details as well as an alternative way to create ISO-8601 standards string from the given string of 46:23:12.

java.time.Duration is modelled on ISO-8601 standards and was introduced with Java-8 as part of JSR-310 implementation. With Java-9 some more convenience methods were introduced.

Demo:

import java.time.Duration;

public class Main {
    public static void main(String[] args) {
        String iso8601DurationString = toIso8601DurationString("46:23:12");
        System.out.println(iso8601DurationString);

        Duration duration = Duration.parse(iso8601DurationString);
        // Default format
        System.out.println(duration);

        // Custom format
        // ####################################Java-8####################################
        String formattedDuration = String.format(
                "%02d Day %02d Hour %02d Minute %02d Second %d Millisecond %d Nanosecond", duration.toDays(),
                duration.toHours() % 24, duration.toMinutes() % 60, duration.toSeconds() % 60,
                duration.toMillis() % 1000, duration.toNanos() % 1000000000L);
        System.out.println(formattedDuration);
        // ##############################################################################

        // ####################################Java-9####################################
        formattedDuration = String.format("%02d Day %02d Hour %02d Minute %02d Second %d Millisecond %d Nanosecond",
                duration.toDaysPart(), duration.toHoursPart(), duration.toMinutesPart(), duration.toSecondsPart(),
                duration.toMillisPart(), duration.toNanosPart());
        System.out.println(formattedDuration);
        // ##############################################################################
    }

    static String toIso8601DurationString(String duration) {
        char[] symbols = "HMS".toCharArray();
        String[] durationParts = duration.split(":");
        StringBuilder sb = new StringBuilder("PT");
        for (int i = 0; i < durationParts.length; i++) {
            sb.append(durationParts[i]).append(symbols[i]);
        }
        return sb.toString();
    }
}

Output:

PT46H23M12S
PT46H23M12S
01 Day 22 Hour 23 Minute 12 Second 0 Millisecond 0 Nanosecond
01 Day 22 Hour 23 Minute 12 Second 0 Millisecond 0 Nanosecond

Learn about the modern date-time API from Trail: Date Time.

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