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How to resolve Unparseable date Exception in Java 8 with Date format yyyy-MM-dd hh:mm a

I have a text file from which I am reading and setting transaction POJO class data, to get the difference between start and end time I need to parse the time information in date object.
DateFormat format = new SimpleDateFormat(dateFormat);
System.out.println("Date format in play:"+dateFormat);
Transaction transaction = storageRepositroy.getTransaction(key);
Date start = format.parse(transaction.getStartDate() + " " + transaction.getStartTime());//line no. 29
Date end = format.parse(transaction.getEndDate() + " " + transaction.getEndTime());
I am getting exception while running this code
Exception is
Date format in play:yyyy-MM-dd hh:mm a
java.text.ParseException: Unparseable date: "2020–03–01 03:15 PM"
at java.text.DateFormat.parse(DateFormat.java:366)
at dc.tech.transaction.util.TimeUtil.calculateAverageTime(TimeUtil.java:29)
yyyy-MM-dd hh:mm a is the date format which I am passing to SimleDateFormat constructor. I am unable to understand and debug why I am getting this error.

java.time
I recommend that you use java.time, the modern Java date and time API, for your date and time work.
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("uuuu\u2013MM\u2013dd");
DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("hh:mm a", Locale.ENGLISH);
String dateString = "2020–03–01";
String timeString = "03:15 PM";
LocalDate date = LocalDate.parse(dateString, dateFormatter);
LocalTime time = LocalTime.parse(timeString, timeFormatter);
LocalDateTime dateTime = date.atTime(time);
System.out.println(dateTime);
Output:
2020-03-01T15:15
With java.time it is straightforward to combine date and time after parsing, so I prefer to parse them individually.
What went wrong in your code?
Credits go to Ajeetkumar for noticing and reporting in comments: The hyphen in your date string is not a usual minus sign or hyphen with character value 2D hexadecimal (45 decimal), but a en dash with character value 2013 hexadecimal (8211 decimal). So when you specify a usual hyphen in your format pattern string, they don’t match, and parsing fails. Instead I am using a Unicode escape for putting the en dash into the format pattern string. Simply pasting it in there would have worked too (provided that you save your .java file with a character encoding that supports it), but I wanted to make the reader aware that something special was going on here, so I preferred the Unicode escape with \u.
There is another problem with your code: You are not providing any locale for your formatter. So it uses the default locale of your JVM. As long as that locale expects PM, parsing will work. If one day you change your locale setting or run your code on a computer or JVM with a different default locale, parsing will suddenly fail, at you may have a hard time figuring out why. I have specified English locale for parsing the time. Some would prefer doing it for the date too even though technically it isn’t necessary.
Links
Oracle tutorial: Date Time explaining how to use java.time.
Unicode Character 'EN DASH' (U+2013) on FileFormat.info.

I always stick to this mantra: use exactly the same format as your date-time string.
In the solutions given below, I have copied your date-time string into the pattern that I've specified for SimpleDateFormat and DateTimeFormatter and replaced the numbers with the corresponding letters e.g. 2020 with yyyy while keeping the rest of things (symbols, space etc.) intact.
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
public class Main {
public static void main(String[] args) throws ParseException {
DateFormat sdf = new SimpleDateFormat("yyyy–MM–dd hh:mm a", Locale.ENGLISH);// Make sure to use Locale
String dateTimeString = "2020–03–01 03:15 PM";// The string copied from the exception you have got
Date date = sdf.parse(dateTimeString);
System.out.println(sdf.format(date));
}
}
Output:
2020–03–01 03:15 PM
Note: The date-time API of java.util and their formatting API, SimpleDateFormat are outdated and error-prone. I suggest you should stop using them completely and switch to the modern date-time API.
Using the modern date-time API:
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy–MM–dd hh:mm a", Locale.ENGLISH);// Make sure to use Locale
String dateTimeString = "2020–03–01 03:15 PM";// The string copied from the exception you have got
System.out.println(LocalDateTime.parse(dateTimeString, dtf));
}
}
Output:
2020-03-01T15:15
Learn more about the modern date-time API at Trail: Date Time.
If you are doing it for your Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

Json response to postgresql datetime conversion Java postgresql

I am getting the JSON responses for the Date time field as follows:
/Date(1534291200000)/ and PT12H18M02S
SELECT CAST('ClearingDate' AS TIMESTAMP) from testdata;
On using CAST functions or to_timestamp I am getting the following error:
ERROR: invalid input syntax for type timestamp: "/Date(1534291200000)/"
SQL state: 22007
How can I convert this to timestamp using postgresql? If not postgresql is there a way to do so in Java?

The solution to directly convert it in PostgreSQL:
to_timestamp(CAST(SUBSTRING (CAST(Clearingdate AS varchar), 9, 10) AS NUMERIC))
from date_test;
I finally figured it out. Thanks a lot for all your inputs.

use timestamp (import java.sql.Timestamp)
String fromJson = "/Date(1534291200000)/";
String ts = fromJson.substring(6, fromJson.length()-2);
Long tsInMillisSec = Long.parseLong(ts);
Timestamp ts = new Timestamp(tsInMillisSec);

Sorry, I don’t know how to do this in PostgreSQL. In Java:
String timestampString = "/Date(1534291200000)/";
String millisString = timestampString.replaceFirst("^/Date\\((\\d+)\\)/$", "$1");
Instant inst = Instant.ofEpochMilli(Long.parseLong(millisString));
System.out.println(inst);
Output is
2018-08-15T00:00:00Z
I am using a regular expression for validating the syntax of the string and taking out just the substring of digits. This number denoted milliseconds since the epoch. The Instant class from java.time, the modern Java date and time API, is the correct one to use for a timestamp (forget about the outdated Timestamp class, we don’t need it anymore).
If you need to store this back into PostgreSQL:
PreparedStatement stmt = yourConnection.prepareStatement(
"insert into your_table(your_timestamp_column) values (?);");
stmt.setObject(1, inst);
Please modify to your database design and situation.
Link: Oracle tutorial: Date Time explaining how to use java.time.

java.time
The date-time API of java.util and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern date-time API.
For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7.
If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.
Instant#ofEpochMilli
The key here is to get an object of Instant out of the milliseconds in the given string. Once you have Instant, you can convert it to other java.time types e.g. ZonedDateTime or even to the legacy java.util.Date.
A note on the regex, \D+: \D specifies a non-digit while + specifies its one or more occurrence(s).
Demo:
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String text = "/Date(1534291200000)/";
// Replace all non-digits i.e. \D+ with a blank string
Instant instant = Instant.ofEpochMilli(Long.parseLong(text.replaceAll("\\D+", "")));
System.out.println(instant);
// Now you can convert Instant to other java.time types e.g. ZonedDateTime
// ZoneId.systemDefault() returns the time-zone of the JVM. Replace it with the
// desired time-zone e.g. ZoneId.of("Europe/London")
ZonedDateTime zdt = instant.atZone(ZoneId.systemDefault());
// Print the default format i.e. the value of zdt#toString
System.out.println(zdt);
// A custom format
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE MMMM dd HH:mm:ss uuuu", Locale.ENGLISH);
String strDateTimeFormatted = zdt.format(dtf);
System.out.println(strDateTimeFormatted);
}
}
Output:
2018-08-15T00:00:00Z
2018-08-15T01:00+01:00[Europe/London]
Wed August 15 01:00:00 2018
How to get java.util.Date from an Instant?
You should avoid using java.util.Date but for whatsoever purpose, if you want to get java.util.Date, all you have to do is to use Date#from as shown below:
Date date = Date.from(instant);
What about PT12H18M02S?
You can parse it to java.time.Duration which is modelled on ISO-8601 standards and was introduced with Java-8 as part of JSR-310 implementation.
If you have gone through the above links, you might have already learnt that PT12H18M02S specifies a duration of 12 hours 18 minutes 2 seconds which you add to a date-time object (e.g. zdt obtained above) to get a new date-time.
Duration duration = Duration.parse("PT12H18M02S");
ZonedDateTime zdtUpdated = zdt.plus(duration);
System.out.println(zdtUpdated);
Output:
2018-08-15T13:18:02+01:00[Europe/London]
Learn about the modern date-time API from Trail: Date Time.
How to use java.time types with JDBC?
The PostgreSQL™ JDBC driver implements native support for the Java 8 Date and Time API (JSR-310) using JDBC 4.2.
Note that ZonedDateTime, Instant and OffsetTime / TIME [ WITHOUT TIMEZONE ] are not supported. Also, note that all OffsetDateTime instances will have to be in UTC (have offset 0). This is because the backend stores them as UTC.
OffsetDateTime odt = zdt.withZoneSameInstant(ZoneOffset.UTC).toOffsetDateTime();
PreparedStatement st = conn.prepareStatement("INSERT INTO mytable (columnfoo) VALUES (?)");
st.setObject(1, odt);
st.executeUpdate();
st.close();

This might work:
select cast(cast('{"dtJson":"2020-10-23 13:40:54"}'::json->'dtJson' as varchar) as timestamp);

How to convert UTC formatted string to calendar in specific timezone?

I'm trying to convert some string that is in UTC time to a java Calendar object that should be set to GMT-5.
My current UTC string input is this:
UTC date : 20050329174411
I use this code (I detect the 'pattern' as shown below):
DateFormat dateFormat = new SimpleDateFormat(pattern);
Date date = dateFormat.parse(utcDate);
calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT-5"));
calendar.setTime(date);
I then printed the time like this:
calendar.getTime()
And I got this result:
GMT date : Tue Mar 29 17:44:11 EST 2005
I need to support theses date/time string patterns:
FORMAT_UTC4 = "yyyy";
FORMAT_UTC6 = "yyyyMM";
FORMAT_UTC8 = "yyyyMMdd";
FORMAT_UTC10 = "yyyyMMddHH";
FORMAT_UTC12 = "yyyyMMddHHmm";
FORMAT_UTC14 = "yyyyMMddHHmmss";
I would be expecting the time to be set to "12:44:11". I have read a couple of examples and I find date time handling pretty confusing. For me, it's always the same, I get some sort of string formatted UTC and I convert it to GMT-5. I really feel it should be easy!
Ref 1 : How can I get the current date and time in UTC or GMT in Java?
Ref 2 : How to handle calendar TimeZones using Java?

You must set the SimpleDateFormat's time zone to UTC before parsing the date. Else, it uses your default timezone.
And to display the date in the "GMT-5" timezone, you should use another DateFormat, with the timezone set to GMT-5, and format the date with this DateFormat. The toString() method of Date uses your default time zone to transform the date into something readable.

java.time
Note that GMT-5 or timezone offset of -05:00 hours is a fixed offset i.e. independent of the DST and type to represent a date-time with timezone offset is OffsetDateTime.
Demo:
import java.time.Instant;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;
public class Main {
public static void main(String[] args) {
Instant instant = Instant.ofEpochMilli(20050329174411L);
OffsetDateTime odt = instant.atOffset(ZoneOffset.of("-05:00"));
// Alternatively
// OffsetDateTime.ofInstant(instant, ZoneOffset.of("-05:00"));
System.out.println(odt);
}
}
Output:
2605-05-15T18:52:54.411-05:00
If you are looking for an automatic adjustment of timezone offset as per the DST, use ZonedDateTime.
Demo:
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Main {
public static void main(String[] args) {
Instant instant = Instant.ofEpochMilli(20050329174411L);
ZonedDateTime zdt = instant.atZone(ZoneId.of("America/Chicago"));
// Alternatively
// ZonedDateTime.ofInstant(instant, ZoneId.of("America/Chicago"));
System.out.println(zdt);
}
}
Output:
2605-05-15T18:52:54.411-05:00[America/Chicago]
Learn more about java.time, the modern date-time API* from Trail: Date Time.
If at all you need an object of java.util.Calendar from this object of ZonedDateTime, you can do so as follows:
Calendar calendar = Calendar.getInstance();
calendar.setTime(Date.from(zdt.toInstant()));
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

Get only the date from the timestamp

This is my Below function in which I am passing timestamp, I need only the date in return from the timestamp not the Hours and Second. With the below code I am getting-
private String toDate(long timestamp) {
Date date = new Date (timestamp * 1000);
return DateFormat.getInstance().format(date).toString();
}
This is the output I am getting.
11/4/01 11:27 PM
But I need only the date like this
2001-11-04
Any suggestions?

Use SimpleDateFormat instead:
private String toDate(long timestamp) {
Date date = new Date(timestamp * 1000);
return new SimpleDateFormat("yyyy-MM-dd").format(date);
}
Updated: Java 8 solution:
private String toDate(long timestamp) {
LocalDate date = Instant.ofEpochMilli(timestamp * 1000).atZone(ZoneId.systemDefault()).toLocalDate();
return date.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
}

You can use this code to get the required results
protected Timestamp timestamp = new Timestamp(Calendar.getInstance().getTimeInMillis());
protected String today_Date=timestamp.toString().split(" ")[0];

java.time
The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API*.
Also, quoted below is a notice from the home page of Joda-Time:
Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.
Solution using java.time, the modern Date-Time API:
You can use Instant#ofEpochSecond to get an Instant out of the given timestamp and then use LocalDate.ofInstant to get a LocalDate out of the obtained Instant.
Demo:
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
public class Main {
public static void main(String[] args) {
// Test
System.out.println(toDate(1636120105L));
}
static LocalDate toDate(long timestamp) {
return LocalDate.ofInstant(Instant.ofEpochSecond(timestamp), ZoneId.systemDefault());
}
}
Output:
2021-11-05
ONLINE DEMO
Learn more about the modern Date-Time API from Trail: Date Time. Check this answer and this answer to learn how to use java.time API with JDBC.
* If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring. Note that Android 8.0 Oreo already provides support for java.time.

Joda-Time
The Joda-Time library offers a LocalDate class to represent a date-only value without any time-of-day nor time zone.
Time Zone
Determining a date requires a time zone. A moment just after midnight in Paris means a date that is a day ahead of the same simultaneous moment in Montréal. If you neglect to specify a time zone, the JVM’s current default time zone is applied – probably not what you want as results may vary.
Example Code
long millisecondsSinceUnixEpoch = ( yourNumberOfSecondsSinceUnixEpoch * 1000 ); // Convert seconds to milliseconds.
DateTimeZone timeZone = DateTimeZone.forID( "America/Montreal" );
LocalDate localDate = new LocalDate( millisecondsSinceUnixEpoch, timeZone );
String output = localDate.toString(); // Defaults to ISO 8601 standard format, YYYY-MM-DD.
Previous Day
To get the day before, as requested in a comment.
LocalDate dayBefore = localDate.minusDays( 1 );
Convert to j.u.Date
The java.util.Date & .Calendar classes should be avoided as they are notoriously troublesome. But if required, you may convert.
java.util.Date date = localDate.toDate(); // Time-of-day set to earliest valid for that date.

Generating UTC Time in java

I want to get the UTC time for 01/01/2100 in Java to '2100-01-01 00:00:00'. I am getting "2100-01-01 00:08:00". Any idea, how to correct this.
public Date getFinalTime() {
Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
DateFormat df = new SimpleDateFormat("dd/MM/yyyy");
Date finalTime = null;
try
{
finalTime = df.parse("01/01/2100");
} catch (ParseException e)
{
e.printStackTrace();
}
calendar.setTime(finalTime);
return calendar.getTime();
}

You need to specify the time zone for the SimpleDateFormat as well - currently that's parsing midnight local time which is ending up as 8am UTC.
TimeZone utc = TimeZone.getTimeZone("UTC");
Calendar calendar = Calendar.getInstance(utc);
DateFormat df = new SimpleDateFormat("dd/MM/yyyy");
df.setTimeZone(utc);
Date finalTime = null;
try
{
finalTime = df.parse("01/01/2100");
} catch (ParseException e)
{
e.printStackTrace();
}
calendar.setTime(finalTime);
As ever though, I would personally recommend using Joda Time which is far more capable in general. I'd be happy to translate your example into Joda Time if you want.
Additionally, I see you're returning calendar.getTime() - that's just the same as returning finalTime as soon as you've computed it.
Finally, just catching a ParseException and carrying on as if it didn't happen is a very bad idea. I'm hoping this is just sample code and it doesn't reflect your real method. Likewise I'm assuming that really you'll be parsing some other text - if you're not, then as Eyal said, you should just call methods on Calendar directly. (Or, again, use Joda Time.)

You need to set the time zone of the SimpleDateFormat object as well, otherwise it assumes the default time zone.
Anyway, it seems like using only a Calendar is enough in your case. Use its setters to set the right values for all fields (year, month, day, hour, etc), and then retrieve the time.

The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API*.
Also, quoted below is a notice at the Home Page of Joda-Time:
Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.
Solution using java.time, the modern API:
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String strDate = "01/01/2100";
DateTimeFormatter dtfInput = DateTimeFormatter.ofPattern("d/M/u", Locale.ENGLISH);
ZonedDateTime zdt = LocalDate.parse(strDate, dtfInput)
.atStartOfDay(ZoneId.of("Etc/UTC"));
// Default format
System.out.println(zdt);
// Getting and displaying LocalDateTime
LocalDateTime ldt = zdt.toLocalDateTime();
System.out.println(ldt);
// A custom format
DateTimeFormatter dtfOutput = DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss", Locale.ENGLISH);
// Alternatively dtfOutput.format(ldt);
String formatted = dtfOutput.format(zdt);
System.out.println(formatted);
// Converting to some other types
OffsetDateTime odt = zdt.toOffsetDateTime();
Instant instant = zdt.toInstant();
System.out.println(odt);
System.out.println(instant);
}
}
Output:
2100-01-01T00:00Z[Etc/UTC]
2100-01-01T00:00
2100-01-01 00:00:00
2100-01-01T00:00Z
2100-01-01T00:00:00Z
ONLINE DEMO
The Z in the output is the timezone designator for zero-timezone offset. It stands for Zulu and specifies the Etc/UTC timezone (which has the timezone offset of +00:00 hours).
Note: The Date-Time without timezone name or timezone offset should be represented by LocalDateTime (which is used for events that are normally not represented with timezone information). In this sense, LocalDateTime is useless in this case and you should use ZonedDateTime itself or Instant or OffsetDateTime. I recommend you also check this answer and this answer if you are dealing with JDBC.
Learn more about java.time, the modern Date-Time API* from Trail: Date Time.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

java.time
Like Arvind Kumar Avinash I very clearly recommend that you use java.time, the modern Java date and time API, for your date and time work. If what you want is a fixed (constant) date and time, use OffsetDateTime.of().
OffsetDateTime finalTime = OffsetDateTime.of(2100, 1, 1, 0, 0, 0, 0, ZoneOffset.UTC);
System.out.println(finalTime);
Output:
2100-01-01T00:00Z
The trailing Z means UTC.
Tutorial link
Oracle tutorial: Date Time explaining how to use java.time.

TimeZone utc = TimeZone.getTimeZone("UTC");
Calendar calendar = Calendar.getInstance(utc);
DateFormat dateformat = new SimpleDateFormat("dd/MM/yyyy");
dateformat.setTimeZone(utc);
Timezone needs to be set.