Any help or hint would be greatly appreciated. From the below code I get this date:2023-01-25 16:30:22.998. How can I get this date: "FrmDt": "2023-01-16T23:59:59.938Z". It has a "T" which I not sure what this mean?

    java.util.Date tsFrom = new java.util.Date();
    Calendar calFrom = Calendar.getInstance();
    calFrom.setTime(tsFrom);
    calFrom.add(Calendar.YEAR, -1);
    tsFrom.setTime(calFrom.getTime().getTime()); // or
    sqlTSFromDate = new Timestamp(calFrom.getTime().getTime());
    System.out.println("From date:"   sqlTSFromDate);

CodePudding user response：

tl;dr

Instant 
.now()
.minus( 
    Period.ofYears( 1 ) 
)
.toString() 

ISO 8601

Study the ISO 8601 standard formats for textually representing date-time values.

Avoid legacy classes

Never use the legacy classes Date, Calendar, Timestamp. They are terribly flawed, designed by people who did not understand date-time handling.

java.time

Instead, use the java.time classes defined in JSR 310.

Apparently you want one year prior to the the current moment as seen in UTC. To represent a moment in UTC, use java.time.Instant class.

Instant oneYearAgoInUtc = 
    Instant 
    .now()
    .minus( 
        Period.ofYears( 1 ) 
    )
;

To generate text in standard ISO 8601, merely call toString. The java.time classes use ISO 8601 formats by default when generating/parsing text.

String output = oneYearAgoInUtc.toString() ; 

The T separates the year-month-day portion from the hour-minute-second portion.

The Z indicates an offset from UTC of zero hours-minutes-seconds.

CodePudding user response：

As several comments said, this is an ISO 8601 date. In java, you can parse or write using SimpleDateFormat. With the Z at the end, makle sure to use UTC/Zulu time.

Amending your code:

public static String ISO_8601 = "yyyyMMdd'T'HHmmss'Z'";
...

    SimpleDateFormat dateFormat = new SimpleDateFormat(ISO_8601);
    dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
    sqlTSFromDate = dateFormat.format(tsFrom)