Develop Reference

Date in String to Date in Date conversion

I'm having date in String format as "2019-10-30 12:17:47". I want to convert this to an instance of Date along with the time so that I can compare two date obejcts.
This is what I've tried:
String dateString = "2019-10-30 12:17:47" //Date in String format
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss"); //sdf
Date d1 = format.parse(dateString);
But here I'm getting exception as "Unparseble date exception".
Kindly help...

What went wrong in your code?
In your format pattern string, yyyy-MM-dd HH-mm-ss, you have got two spaces between the date and the time. Since your date string, 2019-10-30 12:17:47, has got only one space there, your formatter objects by throwing the exception. This was also what Tim Biegeleisen said in a comment. The comment by deHaar is true too: The hyphens between hour, minute and second don’t match the colons in your date string either.
What to do instead?
See the good answer by deHaar

You should really switch to java.time (as already suggested in one of the comments below your question). It isn't more difficult than the outdated temporal classes from java.util but less error-prone and more powerful concerning offsets, time zones, daylight saving time and the multitude of different calendars the world has.
See this little example:
public static void main(String[] args) {
String dateString = "2019-10-30 12:17:47";
// define your pattern, should match the one of the String ;-)
String datePattern = "yyyy-MM-dd HH:mm:ss";
// parse the datetime using the pattern
LocalDateTime ldt = LocalDateTime.parse(dateString,
DateTimeFormatter.ofPattern(datePattern));
// print it using a different (here a built-in) formatting pattern
System.out.println(ldt.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
// or you just use the one defined by you
System.out.println(ldt.format(DateTimeFormatter.ofPattern(datePattern)));
// or you define another one for the output
System.out.println(ldt.format(DateTimeFormatter.ofPattern("MMM dd yyyy HH-mm-ss")));
}
The output on my system looks like this:
2019-10-30T12:17:47
2019-10-30 12:17:47
Okt 30 2019 12-17-47

The date in string you want to format does not match the formatter. See more detail here,
https://docs.oracle.com/javase/tutorial/i18n/format/simpleDateFormat.html
#Test
public void test2() {
String dateString = "2019-10-30 12:17:47"; //Date in String format
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //sdf
try {
Date d1 = format.parse(dateString);
} catch (ParseException e) {
e.printStackTrace();
}
}

There are two ways to do it
first is your way
String dateString = "2019-10-30 12:17:47"; // Date in String format
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); // sdf
Date d1 = format.parse(dateString
second is my way (Local date)
LocalDate resultDate = dateFormat("2019-10-30 12:17:47");
System.out.println(resultDate);
public static LocalDate dateFormat(String textTypeDateTime) {
final DateTimeFormatter dateTimetextFormatter =
DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
return LocalDate.parse(textTypeDateTime, dateTimetextFormatter);
}

Java - SimpleDateFormat parse from String issue

I'm trying to parse the following string to a Date object:
String str = "04/15/2014 10:30:24"
I'm using SimpleDateFormat :
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
java.util.Date orderDate = sdf.parse(str);
java.sql.Date orderSqlDate = new java.sql.Date(orderDate.getTime());
but orderSqlDate always returned: 04/15/2014 00:00:00
how to use SimpleDateFormat in java exactly?

The java.sql.Date javadoc states
To conform with the definition of SQL DATE, the millisecond values
wrapped by a java.sql.Date instance must be 'normalized' by setting
the hours, minutes, seconds, and milliseconds to zero in the
particular time zone with which the instance is associated.
If you're going to use java.sql.Date, there's no way around this.

You are also doing correct.
But to get the result in the format you want, you need to use .format("/your format/") method after parsing the string.
String date = "15/12/2014 10:42:24";
SimpleDateFormat dateParser = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date parseDate = dateParser.parse(date);
formatter.format(parseDate) // this will change format of date as you want.

I don't think the way you parse is wrong. Are you sure you print orderDate right ?
The following code demonstrates both parsing and formatting (printing).
public static void main(String[] args) {
String format = "MM/dd/yyyy HH:mm:ss";
try {
SimpleDateFormat sdf = new SimpleDateFormat(format);
Date orderDate = new SimpleDateFormat(format).parse("04/15/2014 10:30:24");
System.out.println(sdf.format(orderDate));
} catch (Exception e) {
e.printStackTrace();
}
}

Provide Locale in the SimpleDateFormat constructor, otherwise parsing might be dependant on your local settings:
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale.ROOT);

How to convert "MM-dd-yyyy hh:mm" String date format to GMT format?

My Date format is like as "MM-dd-yyyy hh:mm" its not current date ,I have to send this date
to server but before send it need to change this date to GMT format but when I change by following code:
private String[] DateConvertor(String datevalue)
{
String date_value[] = null;
String strGMTFormat = null;
SimpleDateFormat objFormat,objFormat1;
Calendar objCalendar;
Date objdate1,objdate2;
if(!datevalue.equals(""))
{
try
{
//Specify your format
objFormat1 = new SimpleDateFormat("MM-dd-yyyy,HH:mm");
objFormat1.setTimeZone(Calendar.getInstance().getTimeZone());
objFormat = new SimpleDateFormat("MM-dd-yyyy,HH:mm");
objFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
//Convert into GMT format
//objFormat.setTimeZone(TimeZone.getDefault());//);
objdate1=objFormat1.parse(datevalue);
//
//objdate2=objFormat.parse(datevalue);
//objFormat.setCalendar(objCalendar);
strGMTFormat = objFormat.format(objdate1.getTime());
//strGMTFormat = objFormat.format(objdate1.getTime());
//strGMTFormat=objdate1.toString();
if(strGMTFormat!=null && !strGMTFormat.equals(""))
date_value = strGMTFormat.split(",");
}
catch (Exception e)
{
e.printStackTrace();
e.toString();
}
finally
{
objFormat = null;
objCalendar = null;
}
}
return date_value;
}
its not change in required format ,I have tried by above code first try to get current timeZone and after that try change string date into that timezone after that convert GMT.
anyone guide me.
thanks in advance.

Try the below code. The first sysout prints the date object which picks up default OS timezone i.e. IST in my case. The second sysout prints the date in the required format after converting the date to GMT timezone.
If you know the timezone of your date string then set that in the formatter. I assumed you need the same date format in the GMT timezone.
SimpleDateFormat format = new SimpleDateFormat("MM-dd-yyyy,HH:mm");
Date date = format.parse("01-23-2012,09:40");
System.out.println(date);
format.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(format.format(date));

you need to use TimeZone's getRawOffset() method:
Date localDate = Calendar.getInstance().getTime();
TimeZone tz = TimeZone.getDefault();
Date gmtDate = new Date(date.getTime() - tz.getRawOffset());
it
returns the amount of time in milliseconds to add to UTC to get standard time in this time zone. Because this value is not affected by daylight saving time, it is called raw offset.
If you want to consider DST as well (you might want this ;-) )
if (tz.inDaylightTime(ret)) {
Date dstDate = new Date(gmtDate.getTime() - tz.getDSTSavings());
if (tz.inDaylightTime(dstDate) {
gmtDate = dstDate;
}
}
The last check is needed if you are right on the edge of a summer time change and would, for instance, go back into standard time by the conversion.
Hope that helps,
-Hannes

Date to XMLGregorianCalendar with specific format

I am getting a Date object, which i need to convert to XMLGregorian Calendar specific format
I tried below ways
String formattedDate = sdf.format(categoryData.getBulkCollectionTime()); //yyyy-MM-dd HH:mm:ss
XMLGregorianCalendar xmlCal = DatatypeFactory.newInstance().newXMLGregorianCalendar(formattedDate);
dataListType.setTimestamp(xmlCal);
I am getting an exception, for sure I am doing wrong here. But I want to format the Date object into specified format, which is done by sdf.format perfectly.
But how do I create the XMLGregorianCalendar object for the same (from formattedDate)?

You should fixed your date format:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
String date = sdf.format(new Date());
XMLGregorianCalendar xmlCal = DatatypeFactory.newInstance().newXMLGregorianCalendar(date);

You can do it by the date object itself:
String formattedDate = sdf.format(categoryData.getBulkCollectionTime()); //yyyy-MM-dd HH:mm:ss
convertStringToXmlGregorian(formattedDate);
public XMLGregorianCalendar convertStringToXmlGregorian(String dateString)
{
try {
Date date = sdf.parse(dateString);
GregorianCalendar gc = (GregorianCalendar) GregorianCalendar.getInstance();
gc.setTime(date);
return DatatypeFactory.newInstance().newXMLGregorianCalendar(gc);
} catch (ParseException e) {
// Optimize exception handling
System.out.print(e.getMessage());
return null;
}
}

How to format a date String into desirable Date format

I was trying to format a string into date.
For this I have written a code:-
Calendar cal = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
System.out.println(sdf.format( cal.getTime() ));
This is fine..
But now I want to convert a string into a date formatted like above..
For example
String dt="2010-10-22";
And the output should be like this:-
2010-10-22T00:00:00
How do I do this?

String dt = "2010-10-22";
SimpleDateFormat sdfIn = new SimpleDateFormat("yyyy-MM-dd");
ParsePosition ps = new ParsePosition(0)
Date date = sdfIn.parse(dt, pos)
SimpleDateFormat sdfOut = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
System.out.println(sdfOut.format( date ));

This should do it for you, remember to wrap it in a try-catch block just in case.
DateFormat dt = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
try
{
Date today = dt.parse("2010-10-22T00:00:00");
System.out.println("Your Date = " + dt.format(today));
} catch (ParseException e)
{
//This parse operation may not be successful, in which case you should handle the ParseException that gets thrown.
//Black Magic Goes Here
}

If your input is going to be ISO, you could also look at using the Joda Time API, like so:
LocalDateTime localDateTime = new LocalDateTime("2010-10-22");
System.out.println("Formatted time: " + localDateTime.toString());

The same class you use for output formatting of dates can also be used to parse dates on input.
SimpleDateFormat reference
To use your example, to parse the sample date:
String dt = "2010-10-22";
SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(dateFormatter.parse(dt));
The fields that are not specified (ie. hour, minutes, etc) will be 0. So your same code can be used to format the date on output.

Date Format Example
Containing the Conversion of String Date object from one format to another