java date parse exception while conveting UTC to l

问题:

I get a UTC date with following format and how can convert this UTC date to my local time zone?

my input date is 2015-03-17 06:00:00 +0000 and I tried the following coding its gives parsing exception.

My code:

DateFormat utcFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss 'Z'");
utcFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = utcFormat.parse("2015-03-17 06:00:00 +0000"); // java.text.DateFormat.parse(Unknown Source)
utcFormat.setTimeZone(TimeZone.getDefault());
System.out.println(utcFormat.format(date));

回答1:

You have two mistakes in your code.

1. As others already mentioned you have additional ' in your pattern around Z.
2. You specify the pattern as dd-MM-yyyy but try to parse the date as yyyy-MM-dd.

Correct version:

DateFormat utcFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z");
utcFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = utcFormat.parse("2015-03-17 06:00:00 +0000");
utcFormat.setTimeZone(TimeZone.getDefault());
System.out.println(utcFormat.format(date));

回答2:

I think this is due to the quotes in the date pattern.

Try this...

DateFormat utcFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss ZZZZ");

回答3:

Remove ' surrounding Z and try again.

回答4:

I should like to contribute the modern answer. The Date and SimpleDateFormat classes used in the question are long outdated, and today we have so much better. I recommend the modern Java date and time API known as JSR-310 or java.time:

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss Z");
    System.out.println(ZonedDateTime.parse("2015-03-17 06:00:00 +0000", formatter)
            .withZoneSameInstant(ZoneId.systemDefault())
            .format(formatter));

On my computer in the Europe/Copenhagen time zone this prints

2015-03-17 07:00:00 +0100

Using ZoneId.systemDefault() is fragile, though, since any program running on the JVM can change its default time zone and thereby alter the behaviour of the above snippet. If you can, it’s better to use a time zone ID in the region/city format, for example ZoneId.of("Asia/Tomsk") or ZoneId.of("America/Argentina/Rio_Gallegos").

Question: Can I use the modern API with my Java version?

If using at least Java 6, you can.

• In Java 8 and later the new API comes built-in.
• In Java 6 and 7 get the ThreeTen Backport, the backport of the new classes (that’s ThreeTen for JSR-310, where the modern API was first defined).
• On Android, use the Android edition of ThreeTen Backport. It’s called ThreeTenABP, and I think that there’s a wonderful explanation in this question: How to use ThreeTenABP in Android Project.

回答5:

This function is tested and works perfectly with any java.util.Date object.

private SimpleDateFormat getDateFormat() {
    SimpleDateFormat dateFormat = (SimpleDateFormat) SimpleDateFormat.getDateTimeInstance(SimpleDateFormat.SHORT, SimpleDateFormat.DEFAULT, Locale.getDefault());
    String pattern = dateFormat.toLocalizedPattern();
    pattern = pattern.trim();
    dateFormat.applyLocalizedPattern(pattern);
    return dateFormat;
}

//And here is the usage
SimpleDateFormat sdf = getDateFormat();
sdf.format(new Date());

I refactored the code from the following web site which you may find of great use for formatting to different types of java.util.Date objects:

https://www.programcreek.com/java-api-examples/index.php?class=java.text.SimpleDateFormat&method=applyLocalizedPattern

Hope this helps