I have a date string "Wed Dec 02 00:00:00 ICT 2015". I tried to use SimpleDateFormat to convert this string to a date with format "YYYY-mm-DD". The code looks like this:
Date date = new SimpleDateFormat("YYYY-mm-DD").parse("Wed Dec 02 00:00:00 ICT 2015");
But I got an exception:
java.text.ParseException: Unparseable date: "Wed Dec 02 00:00:00 ICT 2015"
Most programming languages have a concept of "date/time" representation, which represents some point in time and allows the application of rules, such as time zones and leap years/seconds and other oddities to be applied.
When parsing a String value, you must know the format that the String is in, let's face it, what does 3/3/3 mean?
Java 8 replaced the existing Date/Calendar API which a much richer and less error prone API and you should make use of it as much as possible.
The first step is to construct a DateTimeFormatter of which represents the desired input format
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss z yyyy", Locale.ENGLISH);
See the JavaDocs for more details on the specifiers.
Next, you want to parse the text using the formatter...
String text = "Wed Dec 02 00:00:00 ICT 2015";
ZonedDateTime zdt = ZonedDateTime.parse(text, formatter);
System.out.println(zdt);
nb: I've used a ZonedDateTime because I want to carry over the time zone information, you could use a LocalDateTime, but that would depend on your underlying needs
This will print 2015-12-02T00:00+07:00[Asia/Bangkok]
I expect that the date will have "YYYY-mm-DD" format
An important concept to get your head around is, the toString value of the a date object has nothing to do with its underlying representation and only represents a human readable representation of the object.
To format the date value into something else, you need to use another DateTimeFormatter...
String formattedDate = DateTimeFormatter.ofPattern("yyyy-MM-dd").format(zdt);
System.out.println(formattedDate);
And the will print 2015-12-02
SimpleDateFormatDoes this serves your purpose:
Date date = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy").parse("Wed Dec 02 00:00:00 ICT 2015");
//convert this date to the desired format
DateFormat target = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(target.format(date));
Date, which a representation of a the number of milliseconds since the unix epoch. You will need to use a different formatter to format the Date instance into a String of the desired format
Date and SimpleDateFormat is strongly discouraged.
parseyourStringusing the format that it's in; thenformatyourDateusing the format that you want it to be in. Also better to use the Java 8 classes than the pre-Java 8 ones.Wed Dec 02 00:00:00 ICT 2015matchYYYY-mm-DD? The pattern and the input need to match before it will have any chance of parsing it. Having said that, you should be using the newerjava.timeAPI insteadparsemethod converts a String to a Date. Theformatmethod converts a Date to a String. You'll need both.SimpleDateFormatandDate. Those classes are poorly designed and long outdated, the former in particular notoriously troublesome. Instead useZonedDateTimeandDateTimeFormatter, both from java.time, the modern Java date and time API.