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Converting date without time for different timezone

I store the date in UTC long and displayed in user timezone. But when I try to store only days without time it misleading to different dates.
Eg: Scheduling event on 05/06/2016 (06 May 2016). This date is unique for all regions without timezone. If user from GMT+5:30 timezone trying to add a event on 05/06/2016 then it ISO-8601 format is 2016-05-05T16:00:00.000Z and milliseconds is 1462464000000.
Then user from GMT timezone try to view this event. The date will be 05/05/2016 instead of 05/06/2016.
Is there any way to convert date without any timezone.

Java 8 provides the solution for your problem. If you can use Java 8, use java.time.LocalDate which represents only the date without the time. Store the long value returned by toEpochDay method.
A sample code is given below:
LocalDate date = LocalDate.of(2016, 5, 4);
// Store this long value
long noOfDays = date.toEpochDay(); // No of days from 1970-01-01
LocalDate newDate = LocalDate.ofEpochDay(noOfDays);
System.out.println(newDate); // 2016-05-04

Always store the whole timestap.
Whenever you want to display just convert the timestamp to whichever timezone you want to convert it to & display it.
These would help in conversions: (Time-stamp to Date or viseversa)
// timestamp to Date
long timestamp = 5607059900000; //Example -> in ms
Date d = new Date(timestamp );
// Date to timestamp
long timestamp = d.getTime();
//If you want the current timestamp :
Calendar c = Calendar.getInstance();
long timestamp = c.getTimeInMillis();
Refer : convert TimeStamp to Date in Java
You may display different date formats using SimpleDateFormat.
Eg:
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class MainClass {
public static void main(String[] args) {
String pattern = "MM/dd/yyyy";
SimpleDateFormat format = new SimpleDateFormat(pattern);
try {
Date date = format.parse("12/31/2006");
System.out.println(date);
} catch (ParseException e) {
e.printStackTrace();
}
// formatting
System.out.println(format.format(new Date()));
}
}

Convert UTC time to local time java Android

Im retrieving some values from a json service and the retrieved datetime values are stored in UTC format.
i've tried a lot of sample codes to convert the datetime values to user local timezone but im still getting the same value after conversion.
This is what i have actually: (copied from other posts)
String sJsonDate = "2015-07-08T12:08:13.0625+00:00";
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
simpleDateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
try {
Date localDateTime = simpleDateFormat.parse(sJsonDate);
} catch (ParseException e) {
e.printStackTrace();
}
The result value (localDateTime) is the same as the original value.
I am in Paraguay (GMT-4) and the resulting values needs to be minus one hour diference, like this: ("2015-07-08 07:13:25") (The values are stored in Argentina)
Help please!

I've found the solution, we are using day light savings so i had to disccount one hour to the resulting datetime.
So, i share the code for someone else:
public Date getDateInTimeZone(Date currentDate, String timeZoneId) {
TimeZone timeZone = TimeZone.getTimeZone(timeZoneId);
Date localDateTime = new Date(currentDate.getTime() + timeZone.getOffset(currentDate.getTime()));
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(localDateTime.getTime());
if (timeZone.useDaylightTime()) {
// time zone uses Daylight Saving
cal.add(Calendar.MILLISECOND, timeZone.getDSTSavings() * -1);// in milliseconds
}
return cal.getTime();
}
Usage:
String sDate = "2015-07-08T12:08:13.0625+00:00";
try {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
Date theDate = simpleDateFormat.parse(sDate);
Date localDateTime = getDateInTimeZone(theDate, TimeZone.getDefault().getID());
} catch (ParseException e) {
e.printStackTrace();
}

SimpleDateFormat returns wrong date value during parse

I m facing a problem:I want to get current time of GMT TimeZone in long.
I m using the following code as given below:
TimeZone timeZoneGmt = TimeZone.getTimeZone("GMT");
long gmtCurrentTime = getCurrentTimeInSpecificTimeZone(timeZoneGmt);
public static long getCurrentTimeInSpecificTimeZone(TimeZone timeZone) {
Calendar cal = Calendar.getInstance();
cal.setTimeZone(timeZone);
long finalValue = 0;
SimpleDateFormat sdf = new SimpleDateFormat(
"MMM dd yyyy hh:mm:ss:SSSaaa");
sdf.setTimeZone(timeZone);
Date finalDate = null;
String date = sdf.format(cal.getTime());
try {
finalDate = sdf.parse(date);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finalValue = finalDate.getTime();
return finalValue;
}
As given in, above method
while formatting
String date = sdf.format(cal.getTime());
I m getting correct current time in GMT but as i do parsing by following code:
finalDate=sdf.parse(date);
Date got changed from current GMT time to 15:35:16 IST 2013 that is current time of my system.
I tried with Calendar as well in another way:
TimeZone timeZoneGmt=TimeZone.get("GMT");
Calendar calGmt = Calendar.getInstance();
calGmt.setTimeZone(timeZoneGmt);
long finalGmtValue = 0;
finalGmtValue = calGmt.getTimeInMillis();
System.out.println("Date......" + calGmt.getTime());
but still getting date as current time of my System Thu Jan 23 15:58:16 IST 2014 Not getting GMT current time.

You've misunderstood how Date works. A Date doesn't have a time zone - if you use Date.toString() you'll always see the default time zone. The long value in a Date is purely the number of milliseconds since the Unix epoch: it doesn't have any concept of time zone or calendar system.
If you want to represent a date and time in a particular time zone and calendar, use Calendar instead - but for getting "the current date and time as a long" you can just use System.currentTimeMillis(), which again does not have anything to do with the system time zone.
Additionally, even if you did want to do manipulation like this, you shouldn't be using string conversions. You're not conceptually performing any string conversions, so why introduce them?
If your aim is to display (as a string) the current date and time in a particular time zone, you should just use something like:
Date date = new Date(); // This will use the current time
SimpleDateFormat format = new SimpleDateFormat(...); // Pattern and locale
format.setTimeZone(zone); // The zone you want to display in
String formattedText = format.format(date);
When working with date and time APIs - particularly bad ones like the Java Calendar/Date API - it's very important that you understand exactly what each value in your system represents.

Parsing time string and changing timezone

I am retrieving data from a webservice that provides a timestamp in the form of HH:mm:ss I am using SimpleDateFormat to convert this string into a date object then change its timezone if needed and also convert it from 24hour to 12 hour time.
Problem: When a time is fed in for 12am it looks like this 00:00:00
so 12:05 is 00:05:00
When i get the results they look like this.
times fed in 22:00:00 to 00:01:00
times retrieved 10:00 pm to 0:01 am
I have been looking around to see if there is a way to fix it but i feel like i will need to make a special case and parse the string myself if it has a 0 in the hours place.
Any help would be greatly appreciated.
public String parseTime(String time) {
String mTime = null;
TimeZone thisTimeZone = TimeZone.getDefault();
TimeZone ourTimeZone = TimeZone.getTimeZone("America/Los_Angeles");
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss", Locale.US);
SimpleDateFormat sdfThisTimeZone = new SimpleDateFormat("K:mm:a",
Locale.getDefault());
Date date = null;
sdfThisTimeZone.setTimeZone(thisTimeZone);
sdf.setTimeZone(ourTimeZone);
try {
date = sdf.parse(time);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mTime = sdfThisTimeZone.format(date.getTime());
//**********************************New: Does Not Work********************************
DecimalFormat nft = new DecimalFormat("00"); mTime = nft.format(mTime);
//**********************************New **********************************************
return mTime;
}
I have tried the line using DecimalFormat but i just copied it into the code for now to see if it would work. Unfortunately it made my app crash. The code that i have posted is executed inside an Async Task so i am not sure if that makes any difference but still thankyou for your help. Eventually i will solve this. But for now it is such a small detail that only occurs for 1 hour at 12am that i am moving on to bigger issues. If anyone can shed some light on this that would be awesome.

String getConvertedDateTime (String dateTime) {
String convertedDateTime = dateTime;
if (convertedDateTime != null
&& !convertedDateTime.equalsIgnoreCase("")
&& !convertedDateTime.equalsIgnoreCase("null")) {
try {
SimpleDateFormat formatter = new SimpleDateFormat("HH:mm:ss");
Calendar calendar = Calendar.getInstance();
java.util.Date convertedDate = formatter
.parse(convertedDateTime);
formatter.setTimeZone(TimeZone.getTimeZone("America/Los_Angeles"));
convertedDateTime = formatter.format(convertedDate.getTime());
} catch (Exception e) {
e.printStackTrace();
}
}
return convertedDateTime;
}

Java ParseException while attempting String to Date parsing

I'm having a hard time Parsing/Formatting a Date string received back from a web service. I've attempted multiple approaches, but with no luck.
Sample Date String:
2011-10-05T03:00:00Z
Exception:
W/System.err(10072): java.text.ParseException: Unparseable date: "2011-10-05T05:00:00Z" (at offset 10)
W/System.err(10072): at java.text.DateFormat.parse(DateFormat.java:626)
Sample Code:
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:SSSS");
Date date = formatter.parse(info.AiringTime);
I've found that if I remove the "T" between the date and the time and replace it with a space, it will format just fine. Anybody have any suggestions?
--UPDATE--
After looking deeper into the API documentation, I found this:
All response DateTime values are in UTC format. You need to apply the UTC offset to calculate the local time for display.
DateTime is a date-and-time value specified in one of the following formats:
UTC format: YYYY-MM-DDThh:mm:ssZ. For example: 2011-03-15T02:00:00Z.
Local time with an offset: YYYY-MM-DDThh:mm:ss + or - hh:mm (positive or negative offset). For example, for US Pacific time: 2011-03-14T06:00:00 -08:00.
Any suggestions on the UTC format approach?

You could try:
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
String dateString = dateString.replace("Z", "GMT+00:00");
Date date = dateFormat.parse(dateString);
The above code should correctly handle the case where a timezone is specified in the date. As Z represents the UTC/GMT timezone it is replaced by GMT so the SimpleDateFormat can interpret it correctly (i would love to know a cleaner way of handling this bit if anyone knows one).

Try,
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");

This pattern should parse the date you provide: "yyyy-MM-dd'T'HH:mm:ss'Z'".
If you want to use SimpleDateFormat and you have a limited number of variations, you can create separate formatters for each pattern and chain them:
Date date = formatter1.parse(info.AiringTime);
if (date == null)
{
date = formatter2.parse(info.AiringTime);
if (date == null)
{
date = formatter2.parse(info.AiringTime);
if (date == null)
{
date = formatter3.parse(info.AiringTime);
}
}
}
or put them in a list and iterate until non-null or no more formatters.
If you have too many patterns for this to be practical, you can parse it yourself or try one of these libraries.

This worked for me
SimpleDateFormat isoDateFormat = new SimpleDateFormat("yyyy-mm-dd'T'hh:mm:ss'Z'");
SimpleDateFormat viewFriendlyDateFormat = new SimpleDateFormat("dd/MMM/yyyy hh:mm:ss aaa");
String viewFriendlyDate = "";
try {
Date date = isoDateFormat.parse(timestamp);
viewFriendlyDate = viewFriendlyDateFormat.format(date);
} catch (ParseException e) {
e.printStackTrace();
}

SimpleDateFormat isoDateFormat = new SimpleDateFormat("yyyy-mm-dd'T'hh:mm:ss'Z'");
SimpleDateFormat viewFriendlyDateFormat = new SimpleDateFormat("dd/MMM/yyyy hh:mm:ss aaa");
String viewFriendlyDate = "";
try {
Date date = isoDateFormat.parse(timestamp);
viewFriendlyDate = viewFriendlyDateFormat.format(date);
} catch (ParseException e) {
e.printStackTrace();
}