Different/Incorrect results in calendar field

Question

I'm trying to add event but it shows a different date that I'm trying to put and what I'm getting.

eventButton.setOnClickListener(
        new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                Calendar calendarEvent = Calendar.getInstance();
                Intent calendarIntent = new Intent(Intent.ACTION_EDIT);
                calendarIntent.setType("vnd.android.cursor.item/event");

                Calendar time = Calendar.getInstance();
                time.clear();
                time.set(2018, 05, 23);

                calendarIntent.putExtra(CalendarContract.Events.TITLE, "Whatever");
                calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME,time.getTimeInMillis());
                calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_END_TIME,time.getTimeInMillis());
                calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_ALL_DAY,true);
                calendarIntent.putExtra(CalendarContract.Events.RRULE, "FREQ=YEARLY");
                startActivity(calendarIntent);

            }
        }
);

I'm getting this Jun 22, instead of May 23: screenshot

Please don’t use 05 for 5. It works, but it’s a bad habit since you will get a compile error once you try 08 for 8. — Ole V.V., Apr 16 '18 at 10:33
FYI, the troublesome old date-time classes such as `java.util.Date`, `java.util.Calendar`, and `java.text.SimpleDateFormat` are now legacy, supplanted by the [*java.time*](https://docs.oracle.com/javase/10/docs/api/java/time/package-summary.html) classes. Much of the *java.time* functionality is back-ported to Java 6 & Java 7 in the [***ThreeTen-Backport***](http://www.threeten.org/threetenbp/) project. Further adapted for earlier Android in the [***ThreeTenABP***](https://github.com/JakeWharton/ThreeTenABP) project. See [*How to use ThreeTenABP…*](http://stackoverflow.com/q/38922754/642706). — Basil Bourque, Apr 17 '18 at 18:50

Ole V.V. · Answer 1 · 2018-04-17T19:13:55.010

    long eventTimeInMillis = LocalDate.of(2018, Month.MAY, 23)
            .atStartOfDay(ZoneOffset.UTC)
            .toInstant()
            .toEpochMilli();

As Jamie Corkhill said in a comment, you need the time at the start of day (00:00) in UTC. The above code not only gives you the time at 00:00 in UTC, it is also pretty clear about that this is what it gives you.

I am using java.time, the modern Java date and time API. I find it much nicer to work with than the long outdated Calendar class.

Question: Can I use java.time on Android?

Yes, java.time works nicely on 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, I’m told) the modern API comes built-in.
In Java 6 and 7 get the ThreeTen Backport, the backport of the new 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.timeto 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.

score 0 · Accepted Answer · 2018-04-15T19:12:15.327

0

The Java Calendar.set() method counts months just like arrays in programming, starting from 0 for January. Therefore, your month should be 4 for May, since January is 0, February is 1, March is 2, and so on. That is what I believe is causing your issue.

You may also use the Month enumeration. That is, instead of using your line

time.set(2018, 05, 23);

Use

time.set(2018, Calendar.May, 23);

I hope this helps.

edited Apr 15 '18 at 19:12

answered Apr 15 '18 at 18:46

Thanks for the answer. – CoDesign Apr 15 '18 at 19:20
You're right, this solves the Month problem but the day is again lesser by one, so, is there any other way for the day too or I just have to increment by one the date I've to add? – CoDesign Apr 15 '18 at 19:24
@CoDesign I'll get back to you on that shortly, I'm going to look into it and test it myself. – Apr 15 '18 at 19:27
@CoDesign From the docs, "If allDay is set to 1 eventTimezone must be TIMEZONE_UTC and the time must correspond to a midnight boundary." That means you should use `Calendar.getInstance(TimeZone.getTimeZone("UTC"));` – Apr 15 '18 at 19:43
@CoDesign I just tested your code on my emulator with the only change of decrementing your month by one as per my answer, and I get May 23rd, which is what you want. What timezone is your device in? It would be helpful if you could log `calendarEvent.getTimeZone().toString();` and show me it. – Apr 15 '18 at 19:53

Different/Incorrect results in calendar field

2 Answers2

Question: Can I use java.time on Android?

Links