Can't convert ISO 8601 date to String in Android

Question

I have an Android application that shows the creation date of a ticket with info I get from the server.

The thing is that I can't parse the string I'm getting I get an exception when I try to parse it with a SimpleDateFormat

This is what I get from the server:

2017-07-04 23:59:51.486559-05

This is the format I use to parse it:

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSX", Locale.ENGLISH);

The exception I'm getting with this approach is:

java.lang.IllegalArgumentException: Unknown pattern character 'X'
 at java.text.SimpleDateFormat.validatePatternCharacter(SimpleDateFormat.java:323)
 at java.text.SimpleDateFormat.validatePattern(SimpleDateFormat.java:312)
 at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:365)
 at com.unipagos.app.wallet.payment.receipts.datamodels.PaymentReceipt.dateFromString(PaymentReceipt.java:320)

I've been at it for several hours and I've also tried with

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSZ", Locale.ENGLISH);

to no avail, getting this exception:

java.text.ParseException: Unparseable date: "2016-05-30 20:41:19.934959+00" (at offset 23)
 at java.text.DateFormat.parse(DateFormat.java:579)
 at com.unipagos.app.wallet.payment.receipts.datamodels.PaymentReceipt.dateFromString(PaymentReceipt.java:326)
 at com.unipagos.app.wallet.payment.receipts.datamodels.PaymentReceipt.loadReceiptJSONObject(PaymentReceipt.java:164)
 at com.unipagos.app.history.HistoryListFragment.populateTransactionList(HistoryListFragment.java:371)
 at com.unipagos.app.history.HistoryListFragment.access$3200(HistoryListFragment.java:83)

Am I missing something?

Answer 1

SimpleDateFormat cannot parse your date-time string. The string has microseconds (6 decimals on the seconds), where SimpleDateFormat only supports milliseconds (3 decimals).

ThreeTenABP

So this seems to be a good occasion for you to abandon the long outdated classes Date and SimpleDateFormat. General experience says that the modern Java date and time API is much nicer to work with. For Android you get it in ThreeTenABP, link below. The rest is straightforward when you know how:

    DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSSX", Locale.ENGLISH);
    OffsetDateTime odt = OffsetDateTime.parse(creationDateFromServer, dtf);
    System.out.println(odt);

This prints

2017-07-04T23:59:51.486559-05:00

This agrees with your input, 2017-07-04 23:59:51.486559-05. And by the way, the printed string is in ISO 8601; this is what the modern classes’ toString() methods produce.

Oldfashioned solution

If you insist on sticking to the outdated classes, one way through is to strip off the last three decimals so there are only three, add two digits to the time zone offset so there are four, and use Z for parsing it:

    creationDateFromServer = creationDateFromServer
            .replaceFirst("(\\.\\d{3})\\d{3}((?:\\+|-)\\d{2})$", "$1$200");
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSZ", Locale.ENGLISH);
    try {
        Date d = df.parse(creationDateFromServer);
        System.out.println(d);
    } catch (ParseException pe) {
        System.out.println(pe + " at offset " + pe.getErrorOffset());
    }

Note how hard it is to read the regular expression. Also this will break if the offset comes as for example +0530 one day. Output is:

Wed Jul 05 06:59:51 CEST 2017

The Date is printed in my local time zone, in this case at offset +0200, so the time printed agrees with 23:59:51.486-0500 on the day before. This means that internally the Date object holds the right point in time.

Link

How to use ThreeTenABP in Android Project