DateTimeFormatter - parsing string with time zone

Question

I have a JSpinner for selecting specific time (with today's date) and I need to convrert the String result into LocalDateTime instance. However, I can't seem to write the regex string right. Could you tell me what am I doing wrong, please?

JSpinner:

        SpinnerDateModel sm = new SpinnerDateModel(date, null, null, Calendar.HOUR_OF_DAY);
        spinnerStart = new JSpinner(sm);
        JSpinner.DateEditor de = new JSpinner.DateEditor(spinnerStart, "hh:mm");
        spinnerStart.setEditor(de);

When checking the value with spinnerStart.getValue().toString(), I get the following:

Mon May 25 12:21:24 CEST 2015

I am trying to parse the string according to this documentation but am getting an exception:

SEVERE [global]
java.time.DateTimeException: Unable to obtain LocalTime from TemporalAccessor: {MinuteOfHour=21, MilliOfSecond=0, NanoOfSecond=0, HourOfAmPm=0, MicroOfSecond=0, SecondOfMinute=24},ISO,Europe/Paris resolved to 2015-05-25 of type java.time.format.Parsed
    at java.time.LocalTime.from(LocalTime.java:409)
    at java.time.LocalDateTime.from(LocalDateTime.java:457)

This is my progress so far:

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE MMM dd hh:mm:ss zzzz yyyy");
LocalDateTime startTime = LocalDateTime.parse(spinnerStart.getValue().toString(), dtf);

I tried using 'V' instead of 'z' and some other choices with offsets as well but cannot seem to figure it out. Thanks for any tips.

Answer 1

So, you have a java.util.Date object, which represents a precise instant on the time-line. And to transform it into a LocalDateTime, you're transforming the Date into a String, and then parse the String.

That's a bad strategy. You shouldn't do that.

Just use the date transformation methods:

LocalDateTime localDateTime = 
    date.toInstant()
        .atZone(ZoneId.systemDefault())
        .toLocalDateTime();

Of course, if you want the value for another time zone than the default one, you'll need to pass the appropriate ZoneId.