System.out.format does not have a way to print date-time easily

[Anil Philip]

I prefer using System.out.format but I see that there is no datatype format to print date and time

        System.out.format("now is %tD\n", ZonedDateTime.now(ZoneId.of("America/Chicago")));

Output:

now is 03/05/24

They are all broken up, unlike System.out.println which will automatically print everything.

        System.out.println(" now is \n" + ZonedDateTime.now(ZoneId.of("America/Chicago")));

now is
2024-03-05T10:51:22.312851400-06:00[America/Chicago]

[Stephan van Hulst]

Okay, so you could do one of these:

System.out.printf("now is %s%n",          ZonedDateTime.now(ZoneId.of("America/Chicago")));

System.out.printf("now is %1$tD %1$tT%n", ZonedDateTime.now(ZoneId.of("America/Chicago")));

[Ron McLeod]

The formatting sequence %tD represents the date/time in the format YY/mm/DD.  If you want some different, then you need to build a custom formatting sequence.

For example:
jshell> System.out.format("now is %1$tY-%1$tm-%1$tdT%1$tH:%1$tM:%1$tS ... %n",    ZonedDateTime.now(ZoneId.of("America/Chicago"))); now is 2024-03-05T11:31:29 ...
%1$ refers to the first argument,  tY specifies year,  tm specifies month, etc.

[Ron McLeod]

I'm sure this is available in the Javadocs somewhere, but this is a good reference for Date and Time Formatting.

[Anil Philip]

Stephan van Hulst wrote:Okay, so you could do one of these:

System.out.printf("now is %s%n",          ZonedDateTime.now(ZoneId.of("America/Chicago")));

Hey, this trick worked! Using format() with %s

        System.out.format("now is %s\n", ZonedDateTime.now(ZoneId.of("America/Chicago")));

now is 2024-03-05T11:40:31.940694800-06:00[America/Chicago]

[Anil Philip]

Ron McLeod wrote:
For example:
jshell> System.out.format("now is %1$tY-%1$tm-%1$tdT%1$tH:%1$tM:%1$tS ... %n",    ZonedDateTime.now(ZoneId.of("America/Chicago"))); now is 2024-03-05T11:31:29 ...

That is really hard to memorize all the flags!
Looking at Stefan's reply using printf, I tried it and found that %s also works for format().

now is 2024-03-05T11:40:31.940694800-06:00[America/Chicago]

[Mike Simmons]

It's not really a trick - this is the standard way to simply invoke toString() on whatever object you're passing.  (It also works on primitives, just printing the value.)  If the toString() is what you want, then that's all you need.  If you need something else, then they have other codes to break the data/time into parts.

[Stephan van Hulst]

When using a format string, use %n for newlines, not \n.

%n is platform independent. \n is not.

[Campbell Ritchie]

Ron McLeod wrote:I'm sure this is available in the Javadocs somewhere. . . .

Of course it is. About forty pages' worth of Javadoc, in the Formatter documentation. The other link you gave might be easier to read.

[Anil Philip]

Mike Simmons wrote:It's not really a trick - this is the standard way to simply invoke toString() on whatever object you're passing..

I didn't think of it before. using the %s flag to automatically call toString().

[Campbell Ritchie]

Anil Philip wrote:. . . That is really hard to memorize all the flags! . . .

You should know better than to try memorising details of the Javadocs. [Except maybe for a cert exam.] That is why the information is there behind a hyperlink.

[Anil Philip]

Stephan van Hulst wrote:When using a format string,

I was wondering. It would be nice to be able to use a text-block as (or in) the format string for format() and also println().

   
// DOES NOT COMPILE
     System.out.format("now is %s %s\n", """
                The textblock says it is time for lunch right now ))
                """, ZonedDateTime.now(ZoneId.of("America/Chicago )); 

But this compiles and prints

        System.out.println("""
     now is \n""" + ZonedDateTime.now(ZoneId.of("America/Chicago")));

now is
2024-03-05T12:29:47.674428500-06:00[America/Chicago]

[Carey Brown]

To get the formatting you want use DateTimeFormatter:

		DateTimeFormatter	dtf = DateTimeFormatter.ofPattern( "yyyy-MM-dd HH:mm:ss" );
		System.out.printf( "Chicago time is now: %s%n",
				dtf.format( ZonedDateTime.now(ZoneId.of("America/Chicago") ) ) );

Output:

Chicago time is now: 2024-03-05 12:33:10

[Ron McLeod]

Anil Philip wrote:I was wondering. It would be nice to be able to use a text-block as (or in) the format string for format() and also println().

   
// DOES NOT COMPILE
     System.out.format("now is %s %s\n", """
                The textblock says it is time for lunch right now ))
                """, ZonedDateTime.now(ZoneId.of("America/Chicago )); 

It's not clear (to me) what you are wanting to do, but with a text block, I would do something like this:jshell> """   ...>The textblock says it is time for lunch right now: %s   ...>""".formatted(ZonedDateTime.now(ZoneId.of("America/Chicago"))); $4 ==> "The textblock says it is time for lunch right now: 2024-03-05T12:36:12.722731422-06:00[America/Chicago]\n"

[Anil Philip]

Ron McLeod wrote:
It's not clear (to me) what you are wanting to do, but with a text block, I would do something like this:jshell> """   ...>The textblock says it is time for lunch right now: %s   ...>""".formatted(ZonedDateTime.now(ZoneId.of("America/Chicago"))); $4 ==> "The textblock says it is time for lunch right now: 2024-03-05T12:36:12.722731422-06:00[America/Chicago]\n"

I don't use jshell but when I try it here, it doesn't compile.

//DOES NOT COMPILE
        System.out.format("""
                The textblock says it is time for lunch right now %s
                """.formatted(ZonedDateTime.now(ZoneId.of("America/Chicago )));

[Anil Philip]

Anil Philip wrote:

//DOES NOT COMPILE
        System.out.format("""
                The textblock says it is time for lunch right now %s
                """.formatted(ZonedDateTime.now(ZoneId.of("America/Chicago )));

correction:

        System.out.format("""
                The textblock says it is time for lunch right now %s
                """.formatted(ZonedDateTime.now(ZoneId.of("America/Chicago" ))));

The textblock says it is time for lunch right now 2024-03-05T12:50:02.058123100-06:00[America/Chicago]

Thanks to all! I never knew about formatted and how to combine text-blocks with sout and soutf.

[Mike Simmons]

Anil Philip wrote:

   
// DOES NOT COMPILE
     System.out.format("now is %s %s\n", """
                The textblock says it is time for lunch right now ))
                """, ZonedDateTime.now(ZoneId.of("America/Chicago )); 

There's no problem with using a text block here.  The problem is that you never closed the quotes after America/Chicago, and you're missing a closing parentheses as well.

[Update - OK, I see this has now been corrected above.]

[Anil Philip]

Mike Simmons wrote:The problem is that you never closed the quotes after America/Chicago, and you're missing a closing parentheses as well.

Thank you. I replied to my earlier post.
Your method is a little different than mine but yours is more in line with the traditional way and what I was trying to do.
Notice it doesn't use formatted().

        System.out.format("now is %s %s\n", """
                The textblock says it is time for lunch right now 
                """, ZonedDateTime.now(ZoneId.of("America/Chicago") ));

[Mike Simmons]

Syntactically, text blocks can be used anywhere you would use a String, really.  As long as you know how to make a text block in general, there are no special tricks for combining them with specific methods like System.out.format().

[Ron McLeod]

Anil Philip wrote:

        System.out.format("""
                The textblock says it is time for lunch right now %s
                """.formatted(ZonedDateTime.now(ZoneId.of("America/Chicago" ))));

There is no need to use System.out.format -- the formatting is performed in the String#formatted method:

System.out.print("""
        The textblock says it is time for lunch right now %s
        """
        .formatted(ZonedDateTime.now(ZoneId.of("America/Chicago"))));

[Anil Philip]

Ron McLeod wrote:
There is no need to use System.out.format -- the formatting is performed in the String#formatted method:

thanks

[Campbell Ritchie]

Ron McLeod wrote:. . . String#formatted method: . . .

I wasn't aware of that method; tt appears to be an instance counterpart of the static String#format() method, which I have known about for ages.