We Keep Coding

SimpleDateFormat not formatting offset date time correctly

I got a timestamp as follows, 2019-10-17T07:10:39.021+10:30 but when I parse through the SimpleDateFormat then print again, it appear as 2019-10-17T07:40:39.021+11:00
Looks like it added the 30min to time then change the time zone. Is there is a way to fix that.
Date date = null;
String value = "2019-10-17T07:10:39.021+10:30";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX", Locale.getDefault());
System.out.println("input :" + value);
try {
date = sdf.parse(value);
} catch (ParseException e) {
e.printStackTrace();
}
System.out.println("output :" + sdf.format(date));
Result
input :2019-10-17T07:10:39.021+10:30
output :2019-10-17T07:40:39.021+11:00
Should be same as input.

The date string you have 2019-10-17T07:10:39.021+10:30consists of offset, so from java-8 you can use OffsetDateTime
A date-time with an offset from UTC/Greenwich in the ISO-8601 calendar system, such as 2007-12-03T10:15:30+01:00.
OffsetDateTime dateTime = OffsetDateTime.parse(date);
System.out.println(dateTime.toString()); //2019-10-17T07:10:39.021+10:30

Why are you using Locale.getDefault(), that parameter is not necessary. Can you try just calling it as below,
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");

How can I reformat date and time?

How can I convert 24 hours time format into 12 hours format? I know this question has been asked many times, but my problem is different. My current time is:
Tue Nov 07 18:44:47 GMT+05:00 2017
I just want 6:44 pm from my date time. I tried this:
private void convertTime(String time)
{
try {
final SimpleDateFormat sdf = new SimpleDateFormat("H:mm");
final Date dateObj = sdf.parse(time);
System.out.println(dateObj);
System.out.println(new SimpleDateFormat("K:mm a").format(dateObj));
} catch (final ParseException e) {
e.printStackTrace();
}
}

final SimpleDateFormat sdf = new SimpleDateFormat("hh:mm");
Using hh will give you 12 hours format and HH 24 hour format. More details on documentation.
Edit:
Your initial format must be the following in order to parse your date string to a Date object:
final SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM d HH:mm:ss 'GMT'Z yyyy");
final Date dateObj = sdf.parse(time);
After that you can format time to your needs.

From SimpleDateFormat documentation:
"h:mm a": 12:08 PM
So the format you need for:
I just want 6:44 pm from my date time
is:
final SimpleDateFormat sdf1 = new SimpleDateFormat("EEE MMM d HH:mm:ss z yyyy");
Date date = sdf1.parse(time);
final SimpleDateFormat sdf = new SimpleDateFormat("h:mm a");
String newDateString = sdf.format(date);

try {
final SimpleDateFormat sdf = new SimpleDateFormat("hh:mm");
final Date dateObj = sdf.parse(time);
System.out.println(dateObj);
System.out.println(new SimpleDateFormat("K:mm a").format(dateObj));
} catch (final ParseException e) {
e.printStackTrace();
}

Parse yyyy-MM-DD String to Date yyyy-MM-DD in Android?

String startDateStr = "2017-02-03"
DateFormat formatter = new SimpleDateFormat("yyyy-MM-DD",Locale.US);
Date date = (Date)formatter.parse(startDateStr);
2017-02-03 date is parsed to Tue Jan 03 00:00:00 GMT+05:45 2017
Did I
miss something?
Update
I needed a string to be converted to a date object
while maintaining the same format.
The reason for this is I want to make use of public boolean after(Date when) method

This will work ^_^
DateFormat inputFormat = new SimpleDateFormat("yyyy-MM-dd");
DateFormat outputFormat = new SimpleDateFormat("dd MMM yyyy");
String startDateStr ="2017-02-03";
Date date = null;
try {
date = inputFormat.parse(startDateStr);
String startDateStrNewFormat = outputFormat.format(date);
} catch (ParseException e) {
e.printStackTrace();
}
Little explanation of your output :
D is Day in year (1-365)
d is day in month (1-31)
Check the document

Use SimpleDateFormat type for fomatter. You are creating DateFormat object but using SimpleDateFormat.
String startDateStr = "2017-02-03"
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd",Locale.US);
Date date = (Date)formatter.parse(startDateStr);

Yes you missed something. You used DD instead of dd in your yyyy-MM-DD format string. Here is how you do it:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String formattedDate = sdf.format(new Date());

How to convert date into gmt in java

DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'SSSX");
df.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println("Current date and time in GMT: " + df.format("2017-01-04"));
The above is my code and when I try to convert the date to gmt I get the error:
Exception in thread "main" java.lang.IllegalArgumentException: Cannot
format given Object as a Date at
java.text.DateFormat.format(DateFormat.java:310) at
java.text.Format.format(Format.java:157) at
Sample.main(Sample.java:24)
Please point out what am I doing wrong.
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'SSSX");
df.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println("Current date and time in GMT: " + df.format(new Date()));
This above code is working fine but I need something that works for any date.
And when I try this code:
try {
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'SSSX");
df.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println("Current date and time in GMT: " + df.parse("2017-01-04"));
} catch(Exception e) {
e.printStackTrace();
}
I am getting Unparseable date: "2017-01-04". Please tell me how to fix it

Try it..
String s = "2016-11-21 13:30:0.0";
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss);
Date d = null;
try
{
d = format.parse(s);
} catch (ParseException e)
{
e.printStackTrace();
}
SimpleDateFormat gmtFormat = new SimpleDateFormat("yyyy-MM-dd'T'SSSX");
gmtFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(gmtFormat.format(d));

When you have a date object then you can format it as you want:
DateFormat format = new SimpleDateFormat("yyyy-MM-dd");
format.setTimeZone(TimeZone.getTimeZone("GMT"));
//create a calendar representing your date.
Calendar cal = Calendar.getInstance();
cal.set(2017, 01, 04);
//format the date object to the pattern you want.
String DateToStr = format.format(cal.getTime());
System.out.println(DateToStr);
If you have your date as string you can also do:
String string = "2017-01-04";
DateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
format1.setTimeZone(TimeZone.getTimeZone("GMT"));
Date date = null;
try {
date = format1.parse(string);
} catch (Exception ex) {
ex.printStackTrace();
}
System.out.println(date);

The below code is to help in understanding better - you can try uncommenting the commented lines and compare the results. The point of interest for you in this whole block is gdf.parse(gmtFormat)
Date date = new Date();
DateFormat idf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
idf.setTimeZone(TimeZone.getTimeZone("IST"));
DateFormat gdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
gdf.setTimeZone(TimeZone.getTimeZone("GMT"));
//String istFormat = idf.format(date);
//System.out.println("IST: "+istFormat);
String gmtFormat = gdf.format(date);
System.out.println("GMT: "+ gmtFormat);
try {
//System.out.println("gmt parsed from istFormat: "+gdf.parse(istFormat));
//System.out.println("ist parsed from istFormat: "+idf.parse(istFormat));
System.out.println("gmt parsed from gmtFormat: "+gdf.parse(gmtFormat));
System.out.println("ist parsed from gmtFormat: "+idf.parse(gmtFormat));
} catch (ParseException e) {
e.printStackTrace();
}

Java convert UTC timestamp to local DateTime

I know there are dozens of answered posts about converting UTC Time/Date To/From local time already but non helped me to figure out what my problem is.
My question is:
By having UTC timestamp, how can i get local DateTime?
This is what I have right now but this just convert the timestamp to DateTime format.
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
sdf.setTimeZone(TimeZone.getDefault());
sdf.format(new Date(timestamp * 1000));
Edited: I'm saving the UTC timestamp on the cloud so every device (Android/iOS) can query and convert to it's time zone.

Try this is working with me
public String getDateCurrentTimeZone(long timestamp) {
try{
Calendar calendar = Calendar.getInstance();
TimeZone tz = TimeZone.getDefault();
calendar.setTimeInMillis(timestamp * 1000);
calendar.add(Calendar.MILLISECOND, tz.getOffset(calendar.getTimeInMillis()));
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date currenTimeZone = (Date) calendar.getTime();
return sdf.format(currenTimeZone);
}catch (Exception e) {
}
return "";
}

You can try this
String DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss a z" ;
final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
String dateTimeString = sdf.format(new Date());
System.out.println(dateTimeString); // current UTC time
long timeStamp=sdf.parse(dateTimeString).getTime(); //current UTC time in milisec
Calendar cal = Calendar.getInstance();
cal.setTime(new Date(timeStamp));
cal.add(Calendar.HOUR_OF_DAY, 5);
cal.add(Calendar.MINUTE, 30);
System.out.println(sdf.format(cal.getTime())); // time relevant to UTC+5.30

U can use Joda time to convert local to UTC and vice-versa
e.g Local to UTC
DateTime dateTimeNew = new DateTime(date.getTime(), DateTimeZone.forID("Asia/Calcutta"));
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
simpleDateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
String datetimeString = dateTimeNew.toString("yyyy-MM-dd HH:mm:ss");
long milis = 0;
try {
milis = simpleDateFormat.parse(datetimeString).getTime();
} catch (ParseException e) {
e.printStackTrace();
}