How to show localized date units in a formatted string in Java/Android?

Question

Let's say I have a period of days:

Period p = Period.ofDays(3);

And I want to format the period with the "days" label in the string to get this string as output:

// "3 days"

...but, I want to localize the "days" component, so I can't use a formatted string like the following, otherwise it will only ever appear correctly in English:

String.format("%d days", numberOfDays); // Won't localize 'days'

What APIs are there in Java/Kotlin/Android to represent a period of time, like hours, days, weeks, years in a locale? I would rather not localize those words by myself if I can let the API do it.

Answer 1

As suggested in one comment, you can use my lib Time4J and use following code:

Period p = Period.ofDays(3);
Locale loc = Locale.ENGLISH; // or any other supported locale
String formatted = PrettyTime.of(loc).print(p); // 3 days

The tutorial also contains a list of currently supported languages. By the way, the Time4J-equivalent for java.time.Period would be net.time4j.Duration<CalendarUnit> if you are interested in other features like normalization or extended ISO-compatibility etc.

Note: If you are on Android then you should rather use the sister library Time4A instead of Time4J but the presented code would be the same.