How to get current timestamp in string format in J

问题:

How to get timestamp in string format in Java? "yyyy.MM.dd.HH.mm.ss"

String timeStamp = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss").format(new Timestamp());

This is what I have, but Timestamp() requires an parameters...

回答1:

Replace

new Timestamp();

with

new java.util.Date()

because there is no default constructor for Timestamp, or you can do it with the method:

new Timestamp(System.currentTimeMillis());

回答2:

Use java.util.Date class instead of Timestamp.

String timeStamp = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss").format(new Date());

This will get you the current date in the format specified.

回答3:

You can make use of java.util.Date instead of Timestamp :

String timeStamp = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss").format(new Date());

回答4:

tl;dr

Use only modern java.time classes. Never use the terrible legacy classes such as SimpleDateFormat, Date, or java.sql.Timestamp.

ZonedDateTime                    // Represent a moment as perceived 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" )  // Specify the time zone using proper Continent/Region name. Never use 3-4 character pseudo-zones such as PDT, EST, IST. 
)                                // Returns a `ZonedDateTime` object. 
.format(                         // Generate a `String` object containing text representing the value of our date-time object. 
    DateTimeFormatter.ofPattern( "uuuu.MM.dd.HH.mm.ss" )
)

java.time & JDBC 4.2

The modern approach uses the java.time classes as seen above.

If your JDBC driver complies with JDBC 4.2, you can directly exchange java.time objects with the database. Use PreparedStatement::setObject and ResultSet::getObject.

Use java.sql only for drivers before JDBC 4.2

If your JDBC driver does not yet comply with JDBC 4.2 for support of java.time types, you must fall back to using the java.sql classes.

The java.sql types, such as java.sql.Timestamp, should only be used for transfer in and out of the database. Immediately convert to java.time types in Java 8 and later.

java.time.Instant

A java.sql.Timestamp maps to a java.time.Instant, a moment on the timeline in UTC.

java.sql.Timestamp ts = myResultSet.getTimestamp( … );
Instant instant = ts.toInstant(); 

Time Zone

Apply the desired/expected time zone to get a ZonedDateTime.

ZoneId zoneId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );

Formatted Strings

Use a DateTimeFormatter to generate your string. The pattern codes are similar to those of java.text.SimpleDateFormat but not exactly, so read the doc carefully.

DateTimeFormatter formatter = DateTimeFormatter.ofPattern( "uuuu.MM.dd.HH.mm.ss" );
String output = zdt.format( formatter );

This particular format is ambiguous as to its exact meaning as it lacks any indication of offset-from-UTC or time zone.

ISO 8601

If you have any say in the matter, I suggest you consider using standard ISO 8601 formats rather than rolling your own. The standard format is quite similar to yours. For example:
2016-02-20T03:26:32+05:30.

The java.time classes use these standard formats by default, so no need to specify a pattern. The ZonedDateTime class extends the standard format by appending the name of the time zone (a wise improvement).

String output = zdt.toString(); // Example: 2007-12-03T10:15:30+01:00[Europe/Paris]

Convert to java.sql

You can convert from java.time back to java.sql.Timestamp. Extract an Instant from the ZonedDateTime.

New methods have been added to the old classes to facilitate converting to/from java.time classes.

java.sql.Timestamp ts = java.sql.Timestamp.from( zdt.toInstant() );

---

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.

回答5:

A more appropriate approach is to specify a Locale region as a parameter in the constructor. The example below uses a US Locale region. Date formatting is locale-sensitive and uses the Locale to tailor information relative to the customs and conventions of the user's region Locale (Java Platform SE 7)

String timeStamp = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss", Locale.US).format(new Date());

回答6:

You can use the following

new java.sql.Timestamp(System.currentTimeMillis()).getTime()

Result : 1539594988651

Hope this will help. Just my suggestion and not for reward points.

回答7:

Use below code to get current timestamps:

Timestamp ts = new Timestamp(date.getTime());

For reference

How to get current timestamps in Java