Parsing date from Calendar in Java

Question

Hi, I am having following function

public static Date parseDate(String date, String format) throws ParseException
 {
         SimpleDateFormat formatter = new SimpleDateFormat(format);
         return formatter.parse(date);
 }

I am using this as follows in my code

Calendar eDate = Calendar.getInstance();
eDate.add(Calendar.DAY_OF_MONTH,10);
Date date = null;
  try {
   date = parseDate(eDate.getTime().toString(),"yyyy-MM-dd hh-mm-ss");
  } catch (ParseException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

But it is throwing -

 java.text.ParseException: Unparseable date

What is the problem here?

Answer 1

You're currently formatting with the default format from java.util.Date, and then parsing with a potentially different format. You should also change your format string - it's currently using a 12 hour clock with no am/pm indicator, and minutes twice. I think you mean: "yyyy-MM-dd HH-mm-ss"

Answer 2

You're inserting a Zulu Timestamp (UNIX), getTime() returns the number of milliseconds since January 1, 1970, 00:00:00 GMT. Then you define the format as yyyy-mm-dd hh-mm-ss and try to parse the timestamp with this pattern. Which doesn't match.

You could use Date date = calendar.getTime(); and then format it via new SimpleDateFormat("yyyy-MM-dd HH-mm-ss").format(date);

Answer 3

You'll be happy to hear that there's never a need to parse a date from a Calendar object: The way to pull a Date out of a Calendar is via the getTime() method.

---

EDIT:

To output the date in eDate in ISO style format:

final DateFormat isoFormat = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
String formattedDate = isoFormat.format(eDate.getTime());

That's untested, but I think it should work.

Answer 4

Don't use toString() for anything like that. toString() should be used only for debug messages.

Use DateFormat.format(..) to produce a string in a predictable form.

Answer 5

you can simply use the date returned by the calendar, instead of transforming it into string and back into a date (apparently using a wrong date format). The date can be obtained by:

eDate.getTime()

There seems to be no need for SimpleDateFormat in your case.

Answer 6

The format is not stored in the Date. It is stored in the String. The Date#toString() returns a fixed format which is described in its Javadoc.

Do the formatting only at the moment you need to display a Date to a human as a String.

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH, 10);
Date date = calendar.getTime();
String formattedDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date);
System.out.println(formattedDate);

Note that MM stands for months and mm for minutes. See also SimpleDateFormat javadoc.

Answer 7

Check the Date.toString() method.

The api states that it returns it in the format:

dow mon dd hh:mm:ss zzz yyyy

which is:

Mon Jan 28 14:22:07 EST 2004

You are telling the parser to expect: 2004-01-28 14-22-07

Answer 8

eDate.getTime().toString()

returns a String representation of a date in this format:

dow mon dd hh:mm:ss zzz yyyy (see the java.util.Date API).

You are trying to parse a date using this format:

yyyy-mm-dd hh-mm-ss .

The code is correctly throwing the ParseException.