want current date and time in "dd/MM/yyyy HH:mm:ss.SS" format

Я использую следующий код, чтобы получить дату в формате "дд / ММ / гггг ЧЧ: мм: сс.СС".

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class DateAndTime{

    public static void main(String[] args) throws Exception{
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss.SS");
        String strDate = sdf.format(cal.getTime());
        System.out.println("Current date in String Format: "+strDate);

        SimpleDateFormat sdf1 = new SimpleDateFormat();
        sdf1.applyPattern("dd/MM/yyyy HH:mm:ss.SS");
        Date date = sdf1.parse(strDate);
        System.out.println("Current date in Date Format: "+date);
    }
}

И я получаю следующий вывод

Current date in String Format: 05/01/2012 21:10:17.287
Current date in Date Format: Thu Jan 05 21:10:17 IST 2012

Пожалуйста, подскажите, что мне следует сделать, чтобы отобразить дату в том же строковом формате (dd / MM / yyyy HH: mm: ss.SS), т. е. я хочу следующий вывод:

Current date in String Format: 05/01/2012 21:10:17.287
Current date in Date Format: 05/01/2012 21:10:17.287

SimpleDateFormat

sdf=new SimpleDateFormat("dd/MM/YYYY hh:mm:ss");
String dateString=sdf.format(date);

Это выдаст результат28/09/2013 09:57:19, как вы ожидали.

Для получения полной программы нажмите здесь

Вы не можете - потому что вы вызываете, Date.toString() который всегда будет включать системный часовой пояс, если это формат даты по умолчанию для языка по умолчанию. Само по себе значение Date не имеет понятия о формате. Если вы хотите отформатировать его определенным образом, используйте SimpleDateFormat.format()... использование Date.toString() почти всегда плохая идея.

Следующий код выдает ожидаемый результат. Это то, что вы хотите?

import java.util.Calendar;
import java.util.Date;

public class DateAndTime {

    public static void main(String[] args) throws Exception {
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss.SS");
        String strDate = sdf.format(cal.getTime());
        System.out.println("Current date in String Format: " + strDate);

        SimpleDateFormat sdf1 = new SimpleDateFormat();
        sdf1.applyPattern("dd/MM/yyyy HH:mm:ss.SS");
        Date date = sdf1.parse(strDate);
        String string = sdf1.format(date);
        System.out.println("Current date in Date Format: " + string);

    }
}

tl;dr

• Use modern java.time classes.


• Never use Date/Calendar/SimpleDateFormat classes.

Example:

ZonedDateTime                                // Represent a moment as seen in the wall-clock time used by the people of a particular region (a time zone).
.now(                                        // Capture the current moment.
    ZoneId.of( "Africa/Tunis" )              // Always specify time zone using proper `Continent/Region` format. Never use 3-4 letter pseudo-zones such as EST, PDT, IST, etc.
)
.truncatedTo(                                // Lop off finer part of this value.
    ChronoUnit.MILLIS                        // Specify level of truncation via `ChronoUnit` enum object.
)                                            // Returns another separate `ZonedDateTime` object, per immutable objects pattern, rather than alter (“mutate”) the original.
.format(                                     // Generate a `String` object with text representing the value of our `ZonedDateTime` object.
    DateTimeFormatter.ISO_LOCAL_DATE_TIME    // This standard ISO 8601 format is close to your desired output.
)                                            // Returns a `String`.
.replace( "T" , " " )                        // Replace `T` in middle with a SPACE.

java.time

The modern approach uses java.time classes that years ago supplanted the terrible old date-time classes such as Calendar & SimpleDateFormat.

want current date and time

Capture the current moment in UTC using Instant.

Instant instant = Instant.now() ;

To view that same moment through the lens of the wall-clock time used by the people of a particular region (a time zone), apply a ZoneId to get a ZonedDateTime.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "Pacific/Auckland" ) ;
ZonedDateTime zdt = instant.atZone( z ) ;

Or, as a shortcut, pass a ZoneId to the ZonedDateTime.now method.

ZonedDateTime zdt = ZonedDateTime.now( ZoneId.of( "Pacific/Auckland" ) ) ;

The java.time classes use a resolution of nanoseconds. That means up to nine digits of a decimal fraction of a second. If you want only three, milliseconds, truncate. Pass your desired limit as a ChronoUnit enum object.

ZonedDateTime
.now( 
    ZoneId.of( "Pacific/Auckland" ) 
)
.truncatedTo(
    ChronoUnit.MILLIS
)

in “dd/MM/yyyy HH:mm:ss.SS” format

I recommend always including the offset-from-UTC or time zone when generating a string, to avoid ambiguity and misunderstanding.

But if you insist, you can specify a specific format when generating a string to represent your date-time value. A built-in pre-defined formatter nearly meets your desired format, but for a T where you want a SPACE.

String output = 
    zdt.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME )
    .replace( "T" , " " )  
;

sdf1.applyPattern("dd/MM/yyyy HH:mm:ss.SS");

Date date = sdf1.parse(strDate);

Never exchange date-time values using text intended for presentation to humans.

Instead, use the standard formats defined for this very purpose, found in ISO 8601.

The java.time use these ISO 8601 formats by default when parsing/generating strings.

Always include an indicator of the offset-from-UTC or time zone when exchanging a specific moment. So your desired format discussed above is to be avoided for data-exchange. Furthermore, generally best to exchange a moment as UTC. This means an Instant in java.time. You can exchange a Instant from a ZonedDateTime, effectively adjusting from a time zone to UTC for the same moment, same point on the timeline, but a different wall-clock time.

Instant instant = zdt.toInstant() ;
String exchangeThisString = instant.toString() ;

2018-01-23T01:23:45.123456789Z

This ISO 8601 format uses a Z on the end to represent UTC, pronounced “Zulu”.

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.