Develop Reference

Formatting a Date from an Excel Sheet

I am reading a date column from an Excel Sheet in my Java program via Apache POI that returns the string Fri Jan 16 00:00:00 EST 2015. I need to format this string to 01/16/2016.
I try the following using the SimpleDateFormat to parse the String to a Date Object, then back to the formatted String I need
String inputDate = excelData.get(20).toString(); // Returns Fri Jan 16 00:00:00 EST 201
Date date = new SimpleDateFormat("MM/dd/yyyy").parse(inputDate);
String outputDate = new SimpleDateFormat("MM/dd/yyyy").format(date);
However the following is returned when trying to parse inputDate
Unparseable date: "Fri Jan 16 00:00:00 EST 2015"
Is my inputDate unreadable or am I missing something here? I've also thought of formatting the cell itself to the proper date format instead - thoughts?

Your problem is on this line:
Date date = new SimpleDateFormat(**"MM/dd/yyyy"**).parse(inputDate);
The date format you've described looks more like:
"DDD MMM DD HH:mm:ss tz yyyy" or something like that.
Use https://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html to find the right formatter in order to read the date.
The output looks fine, given you can read the input string format as the right format into a Date.

Your code tells SimpleDateFormat to use MM/dd/yyyy format to PARSE the date, so of course it can't work, since this is not the format of the string you get.
The POI FAQ at https://poi.apache.org/faq.html#faq-N1008D gives a snippet of code to read a date:
case HSSFCell.CELL_TYPE_NUMERIC:
double d = cell.getNumericCellValue();
// test if a date!
if (HSSFDateUtil.isCellDateFormatted(cell)) {
// format in form of M/D/YY
cal.setTime(HSSFDateUtil.getJavaDate(d));
cellText =
(String.valueOf(cal.get(Calendar.YEAR))).substring(2);
cellText = cal.get(Calendar.MONTH)+1 + "/" +
cal.get(Calendar.DAY_OF_MONTH) + "/" +
cellText;
}
Have you tried that?

Change
Date date = new SimpleDateFormat("MM/dd/yyyy").parse(inputDate);
to
Date date = new SimpleDateFormat("EEE MMM DD HH:mm:ss zzz yyyy").parse(inputDate);
zzz Time zone EST
EEE Day name in week Tuesday
MMM Month in year July
Reference: SimpleDateFormat doc

How to convert date strings from different TimeZones to Date object in one TimeZone

Im working on an RSS reader software. I get items with their pubDate (publish date) values as string, convert them to Date object, and put them to my DB. However, when I check my DB, I saw some interesting values such as the date of tomorrow.
I research this situation and found that it is about time zone value Z. For example when I get "Mon, 26 May 2014 21:24:29 -0500", it becomes "2014-05-27 05:24:29", the next day !
All I want is to get dates in any timezone and convert them to date in common timezone, such as my country's.
Here is my code :
public static String convert(String datestr) throws ParseException {
DateFormat formatter = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz");
Date date = formatter.parse(datestr);
SimpleDateFormat resultFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return resultFormatter.format(date);
}
And I use the method like that :
System.out.println(convert("Mon, 26 May 2014 21:24:29 -0500"));
The output is : 2014-05-27 05:24:29
Any idea ?

Since you haven't set a time zone, it's using your system's default.
Set a specific IANA time zone.
SimpleDateFormat resultFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
resultFormatter.setTimeZone(TimeZone.getTimeZone("America/New_York"));
return resultFormatter.format(date);

Looks like you passed a Date with timezone, but given a wrong format. If you are passing timezone like "-0500" you should rather use:
DateFormat formatter = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z");
Remember that the system will always display the date using the current, default timezone (TimeZone.getDefault()) unless you override it by:
resultFormatter.setTimeZone(...)

This is working as expected. The date is converted as per your system's timezone.
Check the UTC offset of your system and replace it in the sample date string and look at the output.
For e.g: India is UTC+5:30
String datestr="Mon, 26 May 2014 21:24:29 +0530";
output:
2014-05-26 21:24:29
Alternate solution
If you don't want to consider the timezone of the input date string then simply truncate this information and remove zzz from pattern as well as shown in below code:
String datestr = "Mon, 26 May 2014 21:24:29 -0530";
datestr = datestr.replaceAll("\\s[-+](\\d+)$", ""); // truncate the timezone info if not needed
DateFormat formatter = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss"); // remove zzz from the pattern
Date date = formatter.parse(datestr);
SimpleDateFormat resultFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println(resultFormatter.format(date));

Formatting Date from Date Object with only MM/DD/YYYY

Currently using Parse to obtain a date on an object by using:
Date date = object.getCreatedAt();
The returned String when displaying it in a TextView is this:
Mon Mar 17 22:39:27 CET 2014
However I really only want the MM/DD/YYYY to display like so: 3/17/2014
I've tried this:
Date date = object.getCreatedAt();
SimpleDateFormat originalFormat = new SimpleDateFormat("MMM DDD yyyy");
try {
Date originaldate = originalFormat.parse(date.toString());
finalDate = originaldate.toString();
} catch (java.text.ParseException e1) {
e1.printStackTrace();
}
but keep getting a ParseException for "Unparseable date", any idea what's going on? If I were to simply change this line back to this:
SimpleDateFormat originalFormat = new SimpleDateFormat("EEE MMM DDD HH:mm:ss z yyyy");
Then it prints out the full date again just fine with no parse exception, including all the date stuff I don't want.

Don't use parse method, use format instead :
Date date = object.getCreatedAt();
SimpleDateFormat formater = new SimpleDateFormat("M/d/yyyy");
String datestring = formater.format(date); // value is : 3/17/2014

http://docs.oracle.com/javase/6/docs/api/java/util/Date.html#toString()
java.util.Date.toString() method always returns a String of format
dow mon dd hh:mm:ss zzz yyyy
For example, Thu Jan 10 02:00:00 EET 1992.
Your Date format "MMM DDD yyyy" expects a date String like Jan 10 1992 where 10 represents not 10th day of January but 10th day of year 1992.
Therefore to convert a date to String and convert it back to Date object using your format, you need to do
Date originaldate = originalFormat.parse(originalFormat.parse(date.toString()));
Or to convert Date.toString() to Date object,
SimpleDateFormat toStringFormat = new SimpleDateFormat("dow mon dd hh:mm:ss zzz yyyy");
Date originaldate = toStringFormat.parse(date.toString());
Lastly, if you want a Date string with format like 3/17/2014, the correct format is M/d/yyyy.
Refer to http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html for help on how to write Date format.

Java new Date with time stamp in date format

I have used the following
SimpleDateFormat df = new SimpleDateFormat("dd-mm-yyyy hh:mm:ss zzz");
Date date = new Date();
String formattedDate= df.format(date);
Date dateWithTime = df.parse(formattedDate);
i got the formatted date as string when i conver this into date i got error like
java.text.ParseException: Unparseable date: "Tue Feb 26 11:45:43 IST 2013"
How would convert to date or how i format a current date and get as date?

I think your code wouldn't throw ParseException. But it sure would definitely yield wrong output. your format should be:
"dd-MM-yyyy hh:mm:ss zzz"
Note that
MM---> Months
mm---> Minutes
Test with your code with out correcting the format:
Sat Jan 26 06:24:07 GMT 2013
Test with your code with correcting the format:
Tue Feb 26 06:20:51 GMT 2013

The date format should be as follows as shown in the exception. Change it to -
EEE MMM d hh:mm:ss z yyyy

The correct simpledateformat will be
SimpleDateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

Please refer the link for proper date formatting and parsing
SimpleDateFormat

change date format to query database

how do I change date format of the following date
Thu May 17 00:00:00 GMT+05:30 2012
to
2012-05-17 00:00:00
I need it as date and not as string. I am using
new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("")
But its not giving the result.
Actually I am storing the values date wise. So when someone enters the data for the same date again it should overwrite.
If I pass it as date object into the hibernate query it gives the result. But not always. ON few occasions it inserts again that is it inserts duplicate data for the same date. Befroe entering I am adding a method to check if data exists for that date. criteria.add(Restrictions.eq("date", date));

You shouldn't be doing string manipulation at all here. You've said in comments that it's a date/time field in the database, so why would there be any string conversion involved in your code?
Specify parameters in JDBC as java.sql.Date, java.sql.Timestamp or whatever - and then fetch them that way too. Don't do a string conversion. Ignore whatever format happens to be displayed when you query the database in a tool - don't think of the result as having a "format" at all - they're just dates.

String str ="Thu May 17 00:00:00 GMT+05:30 2012";
DateFormat old_format = new SimpleDateFormat("EEE MMM dd hh:mm:ss z yyyy");
Date newDate = null;
try {
newDate = old_format.parse(str);
} catch (ParseException e) {
e.printStackTrace();
}
DateFormat new_format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date = new_format.format(newDate);
System.out.println("==>"+date);

Do exactly as you do now but change parse("") to format(theDate)
theDate being the Date object you want to format
See
http://docs.oracle.com/javase/6/docs/api/java/text/DateFormat.html#format(java.util.Date)

String date = "Thu May 17 00:00:00 GMT+05:30 2012";
String oldFormat = "EEE MMM dd hh:mm:ss z yyyy";
String newFormat = "yyyy-MM-dd HH:mm:ss";
SimpleDateFormat sdf1 = new SimpleDateFormat(oldFormat);
SimpleDateFormat sdf2 = new SimpleDateFormat(newFormat);
sdf2.format(sdf1.parse(date))