convert string to instant with different time component formats [duplicate] - java

I have a java component to format the date that I retrieve. Here is my code:
Format formatter = new SimpleDateFormat("yyyyMMdd");
String s = "2019-04-23 06:57:00.0";
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss.S");
try
{
Date date = simpleDateFormat.parse(s);
System.out.println("Formatter: "+formatter.format(date));
}
catch (ParseException ex)
{
System.out.println("Exception "+ex);
}
The code works great as long as the String s has the format "2019-04-23 06:57:00.0";
My Question is, how to tweak this code so it will work for below scenarios ex,
my s string may have values like
String s = "2019-04-23 06:57:00.0";
or
String s = "2019-04-23 06:57:00";
Or
String s = "2019-04-23";
right now it fails if I don't pass the ms.. Thanks!

Different types
String s = "2019-04-23 06:57:00";
String s = "2019-04-23";
These are two different kinds of information. One is a date with time-of-day, the other is simply a date. So you should be parsing each as different types of objects.
LocalDateTime.parse
To comply with the ISO 8601 standard format used by default in the LocalDateTime class, replace the SPACE in the middle with a T. I suggest you educate the publisher of your data about using only ISO 8601 formats when exchanging date-time values as text.
LocalDateTime ldt1 = LocalDateTime.parse( "2019-04-23 06:57:00".replace( " " , "T" ) ) ;
The fractional second parses by default as well.
LocalDateTime ldt2 = LocalDateTime.parse( "2019-04-23 06:57:00.0".replace( " " , "T" ) ) ;
See this code run live at IdeOne.com.
ldt1.toString(): 2019-04-23T06:57
ldt2.toString(): 2019-04-23T06:57
LocalDate.parse
Your date-only input already complies with ISO 8601.
LocalDate ld = LocalDate.parse( "2019-04-23" ) ;
See this code run live at IdeOne.com.
ld.toString(): 2019-04-23
Date with time-of-day
You can strip out the time-of-day from the date.
LocalDate ld = ldt.toLocalDate() ;
And you can add it back in.
LocalTime lt = LocalTime.parse( "06:57:00" ) ;
LocalDateTime ldt = ld.with( lt ) ;
Moment
However, be aware that a LocalDateTime does not represent a moment, is not a point on the timeline. Lacking the context of a time zone or offset-from-UTC, a LocalDateTime cannot hold a moment, as explained in its class JavaDoc.
For a moment, use the ZonedDateTime, OffsetDateTime, or Instant classes. Teach the publisher of your data to include the offset, preferably in UTC.
Avoid legacy date-time classes
The old classes SimpleDateFormat, Date, and Calendar are terrible, riddled with poor design choices, written by people not skilled in date-time handling. These were supplanted years ago by the modern java.time classes defined in JSR 310.

In case of you have optional parts in pattern you can use [ and ].
For example
public static Instant toInstant(final String timeStr){
final DateTimeFormatter formatter = DateTimeFormatter
.ofPattern("yyyy-MM-dd HH[:mm[:ss[ SSSSSSSS]]]")
.withZone(ZoneId.of("UTC"));
try {
return Instant.from(formatter.parse(timeStr));
}catch (DateTimeException e){
final DateTimeFormatter formatter2 = DateTimeFormatter
.ofPattern("yyyy-MM-dd")
.withZone(ZoneId.of("UTC"));
return LocalDate.parse(timeStr, formatter2).atStartOfDay().atZone(ZoneId.of("UTC")).toInstant();
}
}
cover
yyyy-MM-dd
yyyy-MM-dd HH
yyyy-MM-dd HH:mm
yyyy-MM-dd HH:mm:ss
yyyy-MM-dd HH:mm:ss SSSSSSSS

Related

Change date format Java getting Unparseable date Error

I have a date in the following format:
lastUpdatedDate = "12/14/2021 09:15:17";
I used the following code/format to convert date into yyyy-MM-dd hh:mm:ss format:
SimpleDateFormat dt = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
Date lastUpdatedDateFormatted = dt.parse(lastUpdatedDate);
But it gives me below error:
java.text.ParseException: Unparseable date: "12/14/2021 09:15:17"
output should be: 2021-12-14 09:15:17
How can I achieve this?
Change the format to
SimpleDateFormat dt = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
Date lastUpdatedDateFormatted = dt.parse(lastUpdatedDate);
System.out.println(lastUpdatedDateFormatted);
And it should be able to parse the date then.
As you are wanting to display or output the date in yyyy-MM-dd HH:mm:ss format, you should parse the date first then format the date to desired format.
try {
String lastUpdatedDate = "12/14/2021 09:15:17";
Date lastDate = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss").parse(lastUpdatedDate);
System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(lastDate));
} catch (ParseException e) {
e.printStackTrace();
}
Your formatting pattern fails to match your input string.
And you are using terrible date-time classes that were years ago supplanted by the modern java.time classes defined in JSR 310.
java.time
The modern solution uses the java.time classes.
Your input lacks an indicator of time zone or offset from UTC, so parse as a LocalDateTime object.
LocalDateTime ldt =
LocalDateTime
.parse(
"12/14/2021 09:15:17" ,
DateTimeFormatter.ofPattern( "MM/dd/uuuu hh:mm:ss" ) ;
) ;
Your desired output is nearly compliant with the ISO 8601 standard format used by default in java.time, except for that SPACE in the middle rather than T.
String output = ldt.toString().replace( "T" , " " ) ;

How to parse this specific date data?

I've a csv file with this form :
I don't arrive to parse this type of data.
I try with a simple example but it doesn't work. However, I think my SimpleDateFormat is correct.
Date date = null;
String date1 ="22 févr. 17, 17:11";
SimpleDateFormat formater = null;
formater = new SimpleDateFormat("dd MMM YY , hh:mm ");
try {
date = formater.parse(date1);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Avoid legacy date-time classes
You are using terrible date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310.
java.time
Use only classes from the java.time packages. For a date with time of day but lacking the context of a time zone or offset-from-UTC, that would be LocalDateTime.
Specify a Locale to determine the human language used in translation, and the cultural norms used in deciding issues of abbreviation, punctuation, capitalization, order of parts, and so on.
String input = "1 mars 17, 20:21" ;
DateTimeFormatter f =
DateTimeFormatter
.ofPattern( "d MMM uu, HH:mm" )
.withLocale( Locale.CANADA_FRENCH ) ;
LocalDateTime ldt = LocalDateTime.parse( input , f ) ;
These formatting codes are explained in the Javadoc. Study carefully. Case-sensitive.

Java 8 DateTimeFormatter

I need to replace SimpleDataFormat with Java 8 DateTimeFormatter. Below is the code with SimpleDateFormat.
DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date = sdf.parse(source);
Now I need to change it to DateTimeFormatter. I tried as below
LocalDateTime ld = LocalDateTime.now();
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
Date startdate = dtf.parse(dtf);
Now this is generating exception.
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate localDate = LocalDate.parse("2017-02-11", dtf);
System.out.println(localDate.toString());
if you want Date object from LocalDate,the following works
Date date = Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
As #JonSkeet advised, If you're using Java 8 you should probably avoid java.util.Date altogether
If looking for equivalent of your sdf in DateTimeFormatter try DateTimeFormatter.ISO_LOCAL_DATEExplore the DateTimeFormatter class for more formats.
LocalDateTime time = LocalDateTime.now();
time.format(DateTimeFormatter.ISO_LOCAL_DATE);
Use LocalDate instead of LocalDateTime if intrested in Date only.
tl;dr
java.util.Date.from(
LocalDate.parse( "2017-01-23" )
.atStartOfDay( ZoneId.of( "America/Montreal" ) )
.toInstant()
)
No need of formatting pattern
No formatting pattern needed. Your input string happens to be in standard ISO 8601 format. These standard formats are used by default in the java.time classes for parsing and generating strings.
LocalDate
Use LocalDate for a date-only value, without time-of-day and without time zone.
LocalDate ld = LocalDate.parse( "2017-01-23" );
ZonedDateTime
If you want a date-time, let java.time determine the first moment of the day. Do not assume that first moment is 00:00:00.
Determining first moment of the day requires a time zone. The date varies around the globe by zone.
ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ld.atStartOfDay( z );
If you want to perceive that moment through the lens of UTC, extract an Instant object.
Instant instant = zdt.toInstant();
The Instant is equivalent to the old legacy class java.util.Date. Both represent a moment on the timeline in UTC. The modern class has a finer resolution, nanoseconds rather than milliseconds.
Avoid java.util.Date
As others mentioned, you should stick with the modern java.time classes. But if you must, you can convert. Look to new methods added to the old classes.
java.util.Date d = java.util.Date.from( instant ) ;
One way of doing it would be -
LocalDateTime ld = LocalDateTime.now();
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
String date = ld.format(dtf);

Unparseable MMM-dd-yyyy

I will be direct with my question. I am wondering why I can't parse a fromat MMM-dd-yyyy into yyyy-MM-dd (java.sql.Date format)? Any suggestion on how I am going to convert a String into a format of (yyyy-MM-dd)?
Here is the code:
public DeadlineAction(String deadline){
putValue(NAME, deadline);
deadLine = deadline;
SimpleDateFormat formatter = new SimpleDateFormat("yyyy MM dd");
try {
finalDate = (Date) formatter.parse(deadLine);
}catch(ParseException e) {
JOptionPane.showMessageDialog(null, e.getMessage(),"Error",JOptionPane.ERROR_MESSAGE);
}
}
Thank you
Basically, you can't parse a String in the format of MMM-dd-yyyy using the format of yyyy MM dd, it just doesn't make sense, you need one formatter to parse the value and another to format itm for example
SimpleDateFormat to = new SimpleDateFormat("yyyy MM dd");
SimpleDateFormat from = new SimpleDateFormat("MMM-dd-yyyy");
Date date = from.parse(deadLine);
String result = to.format(date)
The question that needs to be asked is, why you would bother. If your intention is to put this value into the database, you should be creating an instance of java.sql.Date (from the java.util.Date) and using PreparedStatement#setDate to apply it to your query, then letting the JDBC driver deal with it
The answer by MadProgrammer is correct. You must define a formatting pattern to fit the format of your input data string.
You could avoid the problem in the first place by using the java.time framework.
java.time
The java.time framework is built into Java 8 and later (also back-ported to Java 6 & 7 and to Android). These classes supplant the old troublesome legacy date-time classes (java.util.Date/.Calendar).
ISO 8601
Your input strings are apparent is standard ISO 8601 format, YYYY-MM-DD such as 2016-01-23.
The java.time classes use ISO 8601 formats by default when parsing/generating strings that represent date-time values. So no need to specify a formatting pattern.
Parsing string
For a date-only value without time-of-day and without time zone, use LocalDate class.
LocalDate localDate = LocalDate.parse( "2016-01-23" );
Generating string
To generate a string representing that LocalDate object’s value, just call toString to get a string in ISO 8601 format.
String output = localDate.toString(); // 2016-01-23
For other formats, use the java.time.format package. Usually best to let java.time automatically localize to the user’s human language and cultural norms defined by a Locale.
DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDate( FormatStyle.MEDIUM );
Locale locale = Locale.CANADA_FRENCH;
formatter = formatter.withLocale( locale );
String output = localDate.format( formatter );
Or you can specify your own particular pattern. Note that you should still specify a Locale to determine aspects such as the name-of-month or name-of-day. Here is a demo of the pattern that seems to be asked in the Question (not sure as Question is unclear).
DateTimeFormatter formatter = DateTimeFormatter.ofPattern( "MMM-dd-yyyy" );
Locale locale = Locale.US;
formatter = formatter.withLocale( locale );
String output = localDate.format( formatter );
Try something like:
try {
final String deadLine = "Oct-12-2006";
SimpleDateFormat formatter = new SimpleDateFormat("MMM-dd-yyyy");//define formatter for yout date time
Date finalDate = formatter.parse(deadLine);//parse your string as Date
SimpleDateFormat formatter2 = new SimpleDateFormat("yyyy-MM-dd");// define your desired format
System.out.println(formatter2.format(finalDate));//format the string to your desired date format
} catch (Exception e) {
//handle
}
Your example is not unparseable. I removed the dashes from MMM-dd-yyyy to MMM dd yyyy. You can put them back if needed. I also removed the any extra code to make the solution clear.
import java.sql.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
public DeadlineAction(String deadline){
//if deadline has format similar to "December 19 2011"
try {
finalDate = new java.sql.Date(
((java.util.Date) new SimpleDateFormat("MMM dd yyyy").parse(deadline)).getTime());
}catch(ParseException e) {
//Your exception code
e.printStackTrace();
}
}
This works for almost every conversion to sqlDate. Just change SimpleDateFormat("MMM dd yyyy") to what you need it to be.
Example: new SimpleDateFormat("MMM-yyyy-dd").parse("NOVEMBER-2012-30")

Convert java.util.Date to String

I want to convert a java.util.Date object to a String in Java.
The format is 2010-05-30 22:15:52
Convert a Date to a String using DateFormat#format method:
String pattern = "MM/dd/yyyy HH:mm:ss";
// Create an instance of SimpleDateFormat used for formatting
// the string representation of date according to the chosen pattern
DateFormat df = new SimpleDateFormat(pattern);
// Get the today date using Calendar object.
Date today = Calendar.getInstance().getTime();
// Using DateFormat format method we can create a string
// representation of a date with the defined format.
String todayAsString = df.format(today);
// Print the result!
System.out.println("Today is: " + todayAsString);
From http://www.kodejava.org/examples/86.html
Format formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String s = formatter.format(date);
Commons-lang DateFormatUtils is full of goodies (if you have commons-lang in your classpath)
//Formats a date/time into a specific pattern
DateFormatUtils.format(yourDate, "yyyy-MM-dd HH:mm:SS");
tl;dr
myUtilDate.toInstant() // Convert `java.util.Date` to `Instant`.
.atOffset( ZoneOffset.UTC ) // Transform `Instant` to `OffsetDateTime`.
.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME ) // Generate a String.
.replace( "T" , " " ) // Put a SPACE in the middle.
2014-11-14 14:05:09
java.time
The modern way is with the java.time classes that now supplant the troublesome old legacy date-time classes.
First convert your java.util.Date to an Instant. The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds (up to nine (9) digits of a decimal fraction).
Conversions to/from java.time are performed by new methods added to the old classes.
Instant instant = myUtilDate.toInstant();
Both your java.util.Date and java.time.Instant are in UTC. If you want to see the date and time as UTC, so be it. Call toString to generate a String in standard ISO 8601 format.
String output = instant.toString();
2014-11-14T14:05:09Z
For other formats, you need to transform your Instant into the more flexible OffsetDateTime.
OffsetDateTime odt = instant.atOffset( ZoneOffset.UTC );
odt.toString(): 2020-05-01T21:25:35.957Z
See that code run live at IdeOne.com.
To get a String in your desired format, specify a DateTimeFormatter. You could specify a custom format. But I would use one of the predefined formatters (ISO_LOCAL_DATE_TIME), and replace the T in its output with a SPACE.
String output = odt.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME )
.replace( "T" , " " );
2014-11-14 14:05:09
By the way I do not recommend this kind of format where you purposely lose the offset-from-UTC or time zone information. Creates ambiguity as to the meaning of that string’s date-time value.
Also beware of data loss, as any fractional second is being ignored (effectively truncated) in your String’s representation of the date-time value.
To see that same moment through the lens of some particular region’s wall-clock time, apply a ZoneId to get a ZonedDateTime.
ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = instant.atZone( z );
zdt.toString(): 2014-11-14T14:05:09-05:00[America/Montreal]
To generate a formatted String, do the same as above but replace odt with zdt.
String output = zdt.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME )
.replace( "T" , " " );
2014-11-14 14:05:09
If executing this code a very large number of times, you may want to be a bit more efficient and avoid the call to String::replace. Dropping that call also makes your code shorter. If so desired, specify your own formatting pattern in your own DateTimeFormatter object. Cache this instance as a constant or member for reuse.
DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuu-MM-dd HH:mm:ss" ); // Data-loss: Dropping any fractional second.
Apply that formatter by passing the instance.
String output = zdt.format( f );
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old date-time classes such as java.util.Date, .Calendar, & java.text.SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to java.time.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations.
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP (see How to use…).
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time.
Altenative one-liners in plain-old java:
String.format("The date: %tY-%tm-%td", date, date, date);
String.format("The date: %1$tY-%1$tm-%1$td", date);
String.format("Time with tz: %tY-%<tm-%<td %<tH:%<tM:%<tS.%<tL%<tz", date);
String.format("The date and time in ISO format: %tF %<tT", date);
This uses Formatter and relative indexing instead of SimpleDateFormat which is not thread-safe, btw.
Slightly more repetitive but needs just one statement.
This may be handy in some cases.
Why don't you use Joda (org.joda.time.DateTime)?
It's basically a one-liner.
Date currentDate = GregorianCalendar.getInstance().getTime();
String output = new DateTime( currentDate ).toString("yyyy-MM-dd HH:mm:ss");
// output: 2014-11-14 14:05:09
It looks like you are looking for SimpleDateFormat.
Format: yyyy-MM-dd kk:mm:ss
In single shot ;)
To get the Date
String date = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()).format(new Date());
To get the Time
String time = new SimpleDateFormat("hh:mm", Locale.getDefault()).format(new Date());
To get the date and time
String dateTime = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss", Locale.getDefaut()).format(new Date());
Happy coding :)
public static String formateDate(String dateString) {
Date date;
String formattedDate = "";
try {
date = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss",Locale.getDefault()).parse(dateString);
formattedDate = new SimpleDateFormat("dd/MM/yyyy",Locale.getDefault()).format(date);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return formattedDate;
}
If you only need the time from the date, you can just use the feature of String.
Date test = new Date();
String dayString = test.toString();
String timeString = dayString.substring( 11 , 19 );
This will automatically cut the time part of the String and save it inside the timeString.
Here are examples of using new Java 8 Time API to format legacy java.util.Date:
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss:SSS Z")
.withZone(ZoneOffset.UTC);
String utcFormatted = formatter.format(date.toInstant());
ZonedDateTime utcDatetime = date.toInstant().atZone(ZoneOffset.UTC);
String utcFormatted2 = utcDatetime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss:SSS Z"));
// gives the same as above
ZonedDateTime localDatetime = date.toInstant().atZone(ZoneId.systemDefault());
String localFormatted = localDatetime.format(DateTimeFormatter.ISO_ZONED_DATE_TIME);
// 2011-12-03T10:15:30+01:00[Europe/Paris]
String nowFormatted = LocalDateTime.now().toString(); // 2007-12-03T10:15:30.123
It is nice about DateTimeFormatter that it can be efficiently cached as it is thread-safe (unlike SimpleDateFormat).
List of predefined fomatters and pattern notation reference.
Credits:
How to parse/format dates with LocalDateTime? (Java 8)
Java8 java.util.Date conversion to java.time.ZonedDateTime
Format Instant to String
What's the difference between java 8 ZonedDateTime and OffsetDateTime?
The easiest way to use it is as following:
currentISODate = new Date().parse("yyyy-MM-dd'T'HH:mm:ss", "2013-04-14T16:11:48.000");
where "yyyy-MM-dd'T'HH:mm:ss" is the format of the reading date
output: Sun Apr 14 16:11:48 EEST 2013
Notes: HH vs hh
- HH refers to 24h time format
- hh refers to 12h time format
public static void main(String[] args)
{
Date d = new Date();
SimpleDateFormat form = new SimpleDateFormat("dd-mm-yyyy hh:mm:ss");
System.out.println(form.format(d));
String str = form.format(d); // or if you want to save it in String str
System.out.println(str); // and print after that
}
Let's try this
public static void main(String args[]) {
Calendar cal = GregorianCalendar.getInstance();
Date today = cal.getTime();
DateFormat df7 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
String str7 = df7.format(today);
System.out.println("String in yyyy-MM-dd format is: " + str7);
} catch (Exception ex) {
ex.printStackTrace();
}
}
Or a utility function
public String convertDateToString(Date date, String format) {
String dateStr = null;
DateFormat df = new SimpleDateFormat(format);
try {
dateStr = df.format(date);
} catch (Exception ex) {
ex.printStackTrace();
}
return dateStr;
}
From Convert Date to String in Java
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date = "2010-05-30 22:15:52";
java.util.Date formatedDate = sdf.parse(date); // returns a String when it is parsed
System.out.println(sdf.format(formatedDate)); // the use of format function returns a String
Date date = new Date();
String strDate = String.format("%tY-%<tm-%<td %<tH:%<tM:%<tS", date);
One Line option
This option gets a easy one-line to write the actual date.
Please, note that this is using Calendar.class and SimpleDateFormat, and then it's not
logical to use it under Java8.
yourstringdate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(Calendar.getInstance().getTime());

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