Develop Reference

How to cast date and time in Android

In my application i want get some data from server and i should cast date and time!
I receive date and time with this format end_date: "2020-04-08 13:11:14" from server.
I want get now date and time from my device and to calculate with above date (end_date), if this time under 24h i should show for example 15 hour later, but if this time more than 24h i should show 2 days later!
But i don't know how can i it?
Can you help me with send code or send to me other tutorials?!
I searched that but I didn't find anything.

java.time
The modern approach uses java.time classes.
Parse the input string as a LocalDateTime.
To parse, replace the SPACE in the middle with a T to comply with ISO 8601 standard.
String input = "2020-04-08 13:11:14".replace( " " , "T" ) ;
LocalDateTime ldt = LocalDateTime.parse( input ) ;
Your input lacks an indicator of any time zone or offset-from-UTC. So we do not know if this was meant to be 1 PM in Tokyo Japan, 1 PM in Toulouse France, or 1 PM in Toledo Ohio US. So you cannot reliably compare this to the current date and time.
If you want to presume this string was meant to tell time in your time zone, then assign a time zone to get a ZonedDateTime.
ZoneId z = ZoneId.of( "Asia/Tokyo" ) ;
ZonedDateTime then = ldt.atZone( z ) ;
Capture the current moment in the same zone.
ZonedDateTime now = ZonedDateTime.now( z ) ;
Calculate 24 hours later.
ZonedDateTime twentyFourHoursFuture = now.plusHours( 24 ) ;
Compare.
boolean within24Hours = then.isBefore( twentyFourHoursFuture ) ;
Determine elapsed time using the Duration class.
Duration duration = Duration.between( then , now ) ;
If you want to trust the JVM’s current default time zone, call ZoneId.systemDefault. Beware that this default can be changed by other Java code during execution of your app.
ZoneId z = ZoneId.systemDefault() ;
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Try using the datetime library, or you can see this answer.
Also if you can choose, it's a good habit to pass the times in UTC from/to the server, it'll save some localization and timezone troubles.

Converting gmt to ist unparseable date exception

DateFormat utcFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
utcFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
DateFormat indianFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
indianFormat .setTimeZone(TimeZone.getTimeZone("Asia/Kolkata"));
String output = null;
try {
Date timestamp = null;
timestamp = utcFormat.parse(createdAt);
output = indianFormat.format(timestamp);
} catch (ParseException e) {
Log.d("ParseError", String.valueOf(e));
}
I want to convert GMT time of format "2020-03-16T18:50:39.656Z" to IST time of same format as GMT but I am getting unparseable exception

The Z at the end of your createdAt value is an ISO 8601 time zone symbol. To parse it, you need to have X in your date format string, not Z. Change your date format string to "yyyy-MM-dd'T'HH:mm:ss.SSSX" and your program will work.
Alternatively, you could keep Z in the date format string, but give your input as "2020-03-16T18:50:39.656+0000" - that is, use the four digit number to represent the time offset in the input, instead of Z.

tl;dr
Instant
.parse(
"2020-03-16T18:50:39.656Z"
)
.atZone(
ZoneId.of( "Asia/Kolkata" )
)
java.time
You are using terrible date-time classes that were supplanted years ago by the modern java.time classes with the adoption of JSR 310.
ISO 8601
Your input string is in standard ISO 8601 format. The Z on the end means UTC (an offset of zero hours-minutes-seconds), and is pronounced “Zulu”.
The java.time classes use ISO 8601 formats by default. So no need to specify a formatting pattern.
Instant
Parse your input as a Instant, representing a moment as seen in UTC.
String input = "2020-03-16T18:50:39.656Z" ;
Instant instant = Instant.parse( input ) ;
ZonedDateTime
Adjust to India time.
ZoneId z = ZoneId.of( "Asia/Kolkata" ) ;
ZonedDateTime zdt = instant.atZone( z ) ;
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

problems converting date to long

I am pulling data out of an Excel sheet, to load into Hubspot, using Java.
Here is how the data looks:
this date 2018-12-31 becomes Dec 31, 2017 once it's in side Hubspot.
This is wrong!
Here is my code:
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
df.setTimeZone(TimeZone.getTimeZone("UTC"));
Date dt = null;
try {
dt = df.parse(member.getUsageEndDate());
} catch (java.text.ParseException e3) {
//dt = null;
e3.printStackTrace();
}
Long l = dt.getTime();
If I open the data in Notepad, it looks like this: 31-May-2018
How can I get this converted properly?

tl;dr
OffsetDateTime.of(
LocalDate.parse( "2018-12-31" ) ,
LocalTime.MIN ,
ZoneOffset.UTC
)
.toInstant()
.toEpochMilli()
1546214400000
Details
Avoid legacy date-time classes
You are using troublesome old date-time classes long ago made legacy by the arrival of the java.time classes built into Java 8 and later.
ISO 8601
Your input string happens to comply with the ISO 8601 standard formats. These formats are used by default in java.time when parsing/generating strings. So no need to specify a formatting pattern.
LocalDate ld = LocalDate.parse( "2018-12-31" ) ;
First moment of the day
Apparently you need the first moment of the day in UTC for that date. Use OffsetDateTime with constant ZoneOffset.UTC.
OffsetDateTime odt = OffsetDateTime.of( ld , LocalTime.MIN , ZoneOffset.UTC ) ;
Dump to console.
System.out.println( "odt.toString(): " + odt );
See this code run live at IdeOne.com.
odt.toString(): 2018-12-31T00:00Z
Count-from-epoch
You appear to want the count of milliseconds since the epoch reference date of first moment of 1970 in UTC, 1970-01-01T00:00Z. Extract an Instant object, the basic building-block class in java.time, and call its handy Instant::toEpochMilli method.
long millisecondsSinceEpoch = odt.toInstant().toEpochMilli() ;
See this code run live at IdeOne.com.
1546214400000
Going the other direction.
Instant instant = Instant.ofEpochMilli( 1_546_214_400_000L ) ;
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

How do I print a millisecond count from epoch as a date-time in UTC using Java?

I am trying to use Java to format a time in milliseconds into a date in UTC. I have the following code:
long ms = 1427590800000;
Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.ROOT);
cal.setTimeInMillis(ms);
Date date = cal.getTime();
SimpleDateFormat dateFormat = new SimpleDateFormat("YYYY-MM-dd hh:mm:ss");
System.out.println(dateFormat.format(date)); // 2015-03-29 02:00:00
This is printing a time in BST (i.e. using the default time-zone) rather than UTC. It seems like the time-zone being set on the calendar has no bearing on the date being printed.
The actual time in UTC is shown by the following python snippet:
import datetime
ms = 1427590800000
print datetime.datetime.utcfromtimestamp(ms/1000.0) # 2015-03-29 01:00:00
Setting the default JVM time-zone to "UTC" results in the correct date being printed, but this doesn't seem like a safe solution.

java.time
The modern approach uses the industry-leading java.time classes.
Parse as an Instant, a moment in UTC with a resolution of nanoseconds.
long input = 1_427_590_800_000L ;
Instant instant = Instant.ofEpochMilli( input ) ;
ISO 8601
Generate a string in standard ISO 8601 format.
String output = instant.toString() ;
2015-03-29T01:00:00Z
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

You need to set the timezone to the formatter before formatting if you want a desired timezone.
Use dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); and then call dateFormat.format(date)

Date Conversion in Spring is one day off

I have a POST end-point that takes a couple of values, one being endDate and startDate. When the JSON posts in as:
{ "startDate" : "2015-01-30", "endDate" : "2015-12-30" }
Spring converts it to a java.util.Date Object that is always one day behind. In the logs I see:
Validating that startDate Thu Jan 29 16:00:00 PST 2015 < endDate Tue Dec 29 16:00:00 PST 2015
So it got the timezone correct. I had assumed it was related to UTC conversions, but I'm not sure how to configure this or modify it so that it converts it using the proper off-set. The timestamp portion of it isn't required - I only care that the year, day, and month match what is passed in.
if it matters, I'm using Spring (happened with 4.0.6 and 4.1.7) and a POST

tl;dr
LocalDate.parse( "2015-01-30" )
Use the right data type for the job
You are trying to fit a date-only value into a date-time type, java.util.Date. Square peg, round hole. While trying to come up with a time-of-day to associate with your date, a time zone is being injected, hence your problem.
LocalDate
Solution:
Never use the terrible old legacy date-time classes such as java.util.Date. Use only the modern java.time classes.
For a date-only value, use LocalDate.
Your input string happens to be in standard ISO 8601 format. The java.time classes use ISO 8601 formats by default when parsing/generating strings. So no need to specify a formatting pattern.
LocalDate ld = LocalDate.parse( "2015-01-30" ) ;
ZonedDateTime
If you want a moment, a date with a time-of-day, let java.time determine the first moment of the day. Never assume that moment is 00:00:00. In some zones on some dates it may be another time such as 01:00:00 because of anomalies such as Daylight Saving Time (DST).
ZonedId z = ZoneId.of( "America/Montreal" ) ;
ZonedDateTime zdt = ld.atStartOfDay( z ) ; // Let java.time determine the first moment of that date in that zone.
Instant
To adjust from to UTC (same moment, different wall-clock time), extract an Instant.
Instant instant = zdt.toInstant() ; // Adjust to UTC. Same moment, same simultaneous point on the timeline, different wall-clock time.
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

String str="2015-01-30";
try{
SimpleDateFormat isoFormat = new SimpleDateFormat("yyyy-MM-dd");
isoFormat.setTimeZone(TimeZone.getTimeZone("PST"));
Date date = isoFormat.parse(str);
System.out.println(date);
}catch(ParseException e){
e.printStackTrace();
}

Check here http://docs.spring.io/spring/docs/current/spring-framework-reference/html/mvc.html#mvc-ann-webdatabinder how to customize automatic Spring conversion:
#Controller
public class MyFormController {
#InitBinder
public void initBinder(WebDataBinder binder) {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
dateFormat.setLenient(false);
binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
}
// ...
}