We Keep Coding

Time String to time representation Java

I have a string like this 210115 I want to represent it as 21:01:15 any ideas?.
I tried using Gregorian calendar but it adds date to it which I don't want
SimpleDateFormat sdf = new SimpleDateFormat("HHmmss");
Date date = new Date();
try{
date = sdf.parse("210115");
}
catch(Exception e){
}
Calendar calendar = GregorianCalendar.getInstance();
calendar.setTime(date);
System.out.print(calendar.getTime());
Output is Thu Jan 01 21:01:15 UTC 1970 but what I want is just 21:01:15
Thanks.

To output a formatted date, you use another SimpleDateFormat object with a pattern with the format you want.
In this case, it sounds like you might want to use something like
SimpleDateFormat outputFormat = new SimpleDateFormat("HH:mm:ss");
System.out.println( outputFormat.format(date) );

So what you want is just a time, without time zone. I would recommend using the LocalTime class, which is exactly that, instead of the Date class.
LocalTime time = LocalTime.parse("210115", DateTimeFormatter.ofPattern("HHmmss"));

If u r getting the date string in "210115" this format and you want it in "21:01:15" format then why are you using date format.
Simply do string operation as:
String time="210115";
String newtime=time.substring(0,2)+":"+time.substring(2,4)+":"+time.substring(4,6);
System.out.println(newtime);
you will get the required format.21:01:15

Conversion of UTC to IST time in java is working in LOCAL but not in CLOUD SERVER

I am working in date conversion in java in that i am using following code snippet to convert the UTC time to IST format.It is working properly in the local when i run it but when i deploy it in server its not converting , its displaying only the utc time itself.Is there any configuaration is needed in server side.Please help me out.
CODE SNIPPET:
DateFormat sdf = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
String pattern = "dd-MM-yyyy HH:mm:ss";
SimpleDateFormat formatter;
formatter = new SimpleDateFormat(pattern);
try {
String formattedDate = formatter.format(utcDate);
Date ISTDate = sdf.parse(formattedDate);
String ISTDateString = formatter.format(ISTDate);
return ISTDateString;
}

Java Date objects are already/always in UTC. Time Zone is something that is applied when formatting to text. A Date cannot (should not!) be in any time zone other than UTC.
So, the entire concept of converting utcDate to ISTDate is flawed.
(BTW: Bad name. Java conventions says it should be istDate)
Now, if you want the code to return the date as text in IST time zone, then you need to request that:
DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
formatter.setTimeZone(TimeZone.getTimeZone("Asia/Kolkata")); // Or whatever IST is supposed to be
return formatter.format(utcDate);

Using Java 8 New API,
Instant s = Instant.parse("2019-09-28T18:12:17Z");
ZoneId.of("Asia/Kolkata");
LocalDateTime l = LocalDateTime.ofInstant(s, ZoneId.of("Asia/Kolkata"));
System.out.println(l);

Java: Compare dates on same timezone

Given:
SimpleDateFormat sd = new SimpleDateFormat ("yy-MM-dd hh:mm:ss.SSS");
sd.setTimeZone(TimeZone.getTimeZone("GMT"));
Date d = sd.parse("a date similar to now on local computer");
if I compare d.getTime() with new Date().getTime(), the values are different with more than one hour. Why?

Check your timezones. You are comparing a time that isn't in GMT.

You're explicitly setting your SimpleDateFormat to parse in GMT, which means that when you parse the current clock time, you're getting the moment of time when that time occurred, in the GMT time zone. If you're not in the GMT time zone, that won't be "now".

Date objects don't know anything about timezones - there is no explicit timezone information in a Date object. A Date object represents an "absolute" moment in time (it's a timestamp). This means you should not think of a Date object as "a date in a certain timezone" - it has no timezone.
Suppose that from some source you get a String that contains a date and time, without an explicit timezone mentioned in it, for example: 2014-12-16 17:30:48.382. Suppose that you know that this date and time is in the GMT timezone.
You could then parse it to a Date object with an appropriate SimpleDateFormat object:
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
// Set the timezone of the SimpleDateFormat to GMT, because you know the string
// should be interpreted as GMT
fmt.setTimeZone(TimeZone.getTimeZone("GMT"));
// Parse the String into a Date object
Date dateTime = fmt.parse("2014-12-16 17:30:48.382");
// Date object which is set to "now"
Date now = new Date();
// Compare it to "now"
if (dateTime.before(now)) {
System.out.println("The specified date is in the past");
} else if (dateTime.after(now)) {
System.out.println("The specified date is in the future");
} else {
System.out.println("The specified date is now");
}
If you want to print the date in a certain timezone, then do so by formatting it with a SimpleDateFormat set to the appropriate timezone.
DateFormat outfmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS z");
outfmt.setTimeZone(TimeZone.getTimeZone("EDT"));
// Will print dateTime in the EDT timezone
System.out.println(outfmt.format(dateTime));

Java datetime format convert

date here my problem:
String datetime = "2012-03-24 23:20:51";
I know that that string is in UTC timezone.
I need to convert this string to format "yyy-mm-dd'T'HH:mm:ssZ".
To do this I'm using following code:
SimpleDateFormat inFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
inFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
Date inDate = inFormatter.parse(datetime);
SimpleDateFormat outFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
outFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
String output = outFormatter.format(inDate);
The problem is that this code is running on a server with timezone UTC+1 and the result it gave me is this:
output = "2012-03-24T21:20:51+0000"
It removes 2 hours from the initial time and puts the UTC timestamp (0000).
Can you please help me solving this?
Thank you.

If the output format is UTC+1 then you should use that in the outformatter instead of UTC.
outFormatter.setTimeZone(TimeZone.getTimeZone("UTC+01:00"));
Also, if you don't want the +0000 at the end then remove the Z
SimpleDateFormat outFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");

Help Needed with Date Format in java

I have My Database data in this format
18-NOV-10
I have to pass the same format into java.util.Date like this
Date date = new java.util.Date(dateformater);
so that the result of java.util.Date is like this 18-NOV-10
Is this possible ??
I tried this way
String strDate = "12-NOV-07";
SimpleDateFormat sdfSource = new SimpleDateFormat("dd-MMM-yy");
Date date = sdfSource.parse(strDate);
System.out.println(date);
But i am getting the result as "Mon Nov 12 00:00:00 IST 2007 " which i want it only
12-NOV-07"

You can use java.text.DateFormat (actually SimpleDateFormat) to get you where you want to go, but maybe you shouldn't be storing the dates as strings in your database. It will do output and parsing.
SimpleDateFormat sdf =
new SimpleDateFormat("DD-MMM-YY");
Date parsed = sdf.parse(dateString);
See http://javatechniques.com/blog/dateformat-and-simpledateformat-examples/
Once you get the Date, you can turn it into the format you want but it will be held in memory as a Date object. You can get it in the form you want using
String dateString = sdf.format(parsed);

As others have pointed out, you should probably store your dates as dates, not strings; nevertheless...
If you want to turn a Date back into a string in that format you can use the following:
DateFormat formatter = new SimpleDateFormat("dd-MMM-yy");
Date date = new Date();
String dateStr = formatter.format(date); // Gives "22-May-11"
If you need MAY instead of May, just use toUpperCase() on the resultant string.

DateFormat sdf = new SimpleDateFormat("dd-MMM-yy");
Date d = sdf.parse("18-NOV-10");

Try System.out.println(sdfSource.format(date).toUpperCase()); instead. The Date object will always have a time component to it; there is no way to "disable" that feature. What you can do instead is to ignore it in your calculations and display. If all Date objects you use are set to the same time of the day, then you can safely ignore the effect of the time component in your comparisons. If you look carefully, the time component of your Date object is set to midnight.