Unparseable Date: 'Day name in week' (SimpleDateFormat)

Question

I'm trying to convert a date from String to a Date object:

String dateString = "Mon, 04 Sep 2017 18:30:28";
String dateFormat = "EEE, dd MMM yyyy HH:mm:ss";

Results in the following exception:

java.text.ParseException: Unparseable date: "Mon, 04 Sep 2017 18:30:28"

I tried different strings and formats and the problems seems to be the name of week ('EEE'). Without it works perfectly.

Also this works perfectly:

String dateString = "04 Sep 2017 18:30:28, Mon";
String dateFormat = "dd MMM yyyy HH:mm:ss, EEE";

Answer 1

Month and weekdays are abbreviated text. The text is language dependent and if you don't provide a specific Locale when instantiating the SimpleDateFormatter the system's Locale is used instead. The reason why your parsing fails with the weekday and not the month can be that the abbreviated name of the month in your system's default language is coincidentally the same as in English.

Here is some code how you should parse a date with text:

SimpleDateFormat formatter = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss", Locale.ENGLISH);
formatter.setLenient(false);
ParsePosition pos = new ParsePosition(0);
return formatter.parse(toParse, pos);

with toParse being a string containing your date as text.

Answer 2

You haven't added the locale which must have caused parse exception while parsing text(s) for Day Of Week & Month

    public static void main(String[] args) throws ParseException {
        String dateString = "Mon, 04 Sep 2017 18:30:28";
        SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss", Locale.ENGLISH);
        System.out.println(dateFormat.parse(dateString));
    }

Produces the following output

Mon Sep 04 18:30:28 IST 2017