java date in mmddhhmmss format

Question

I want to add date to the file so i maintain archive. I want date in this format: mmddhhmmss

So the file name is "cGroup0307131614", just that i want to add timestamp. Not necessary it should be mmddhhmmss format but a format that maintains timestamp.

I tried the foll:

java.util.Date date= new java.util.Date();
     System.out.println(new Timestamp(date.getTime()));

But o/p is 2013-03-07 14:59:30.252. I dont want any spaces colons or special characters.

Answer 1

SimpleDateFormat simpleDateFormat =
            new SimpleDateFormat("MMddhhmmss");
String dateAsString = simpleDateFormat.format(new Date());
System.out.println(dateAsString);

Output:

0307114712

Answer 2

tl;dr

ZonedDateTime
    .now( ZoneId.of( "America/Montreal" ) )
    .format( DateTimeFormatter.ofPattern( "MMddHHmmss" ) )

java.time

The modern way is with the java.time classes which supplant the old legacy date-time classes.

Instant

Grab the current moment in UTC with the Instant class. 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).

Instant instant = Instant.now();  // UTC

May be best to stick with UTC. If so, transform to the more flexible OffsetDateTime for formatting. Specify ZoneOffset.UTC constant.

OffsetDateTime odt = instant.atOffset( ZoneOffset.UTC );

DateTimeFormatter

Define a DateTimeFormatter for your desired format. I do not recommend leaving out the year, but if you insist, here we go.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "MMddHHmmss" );

Create a String with that formatter.

String output = odt.format( f );

ZonedDateTime

Apply a time zone to see the same moment through the lens of a particular region’s wall-clock time.

Specify a proper time zone name in the format of continent/region. 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( "America/Montreal" );
ZonedDateTime zdt = instant.atZone( z );

Use DateTimeFormatter to generate a String, as seen above.

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, & 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. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8 and 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 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….

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.