Time without date

yaugenka :

I get time with time zone (without date component) from a PostgreSQL server in json like this { "time": "03:00:00+01" }. How do I handle this in Android? Is there any structure which can hold just time without date? Or converting it to the epoch Date representation i.e. Thu Jan 01 03:00:00 GMT+01:00 1970 is the only good solution?

Ole V.V. :

OffsetTime from java.time and ThreeTenABP

An OffsetTime is a time of day without date and with an offset from UTC. It thus very precisely models the information in your string from JSON. So I would clearly prefer it over Date. Also because the Date class is poorly designed and long outdated.

    String timeStringFromJson = "03:00:00+01";
    DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("HH:mm:ssX");
    OffsetTime parsedTime = OffsetTime.parse(timeStringFromJson, timeFormatter);
    System.out.println("Parsed time: " + parsedTime);

Output from this snippet is:

Parsed time: 03:00+01:00

As a detail that may or may not matter to you, the offset from the string is retained, contrary to what Date can do because a Date hasn’t got a time zone or offset.

Question: Doesn’t java.time require Android API level 26?

java.time works nicely on both older and newer Android devices. It just requires at least Java 6.

• In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
• In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
• On (older) Android use the Android edition of ThreeTen Backport. It’s called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

Links

• Oracle tutorial: Date Time explaining how to use java.time.
• Java Specification Request (JSR) 310, where java.time was first described.
• ThreeTen Backport project, the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
• ThreeTenABP, Android edition of ThreeTen Backport
• Question: How to use ThreeTenABP in Android Project, with a very thorough explanation.