Using the DATETIME type

When calling a Java method with an expression evaluating to a DATETIME, the runtime system converts the DATETIME value to an instance of the com.fourjs.fgl.lang.FglDateTime class implemented in $FGLDIR/lib/fgl.jar. You can then manipulate the DATETIME from within the Java code.

You must add $FGLDIR/lib/fgl.jar to the class path in order to compile Java code with com.fourjs.fgl.lang.FglDateTime class.

The com.fourjs.fgl.lang.FglDateTime class implements the following:

Table 1. Fields of the com.fourjs.fgl.lang.FglDateTime class
Field	Description
`final static int YEAR`	Time qualifier for year
`final static int MONTH`	Time qualifier for month
`final static int DAY`	Time qualifier for day
`final static int HOUR`	Time qualifier for hour
`final static int MINUTE`	Time qualifier for minute
`final static int SECOND`	Time qualifier for second
`final static int FRACTION`	Time qualifier for fraction (start qualifier)
`final static int FRACTION1`	Time qualifier for fraction(1) (end qualifier)
`final static int FRACTION2`	Time qualifier for fraction(2) (end qualifier)
`final static int FRACTION3`	Time qualifier for fraction(3) (end qualifier)
`final static int FRACTION4`	Time qualifier for fraction(4) (end qualifier)
`final static int FRACTION5`	Time qualifier for fraction(5) (end qualifier)

Table 2. Methods of the com.fourjs.fgl.lang.FglDateTime class
Method	Description
`static int encodeTypeQualifier( int startUnit, int endUnit)`	Returns the encoded type qualifier for a datetime with to datetime qualifiers passed: encoded qualifier = (length * 256) + (startUnit * 16) + endUnit Where length defines the total number of significant digits in this time data. For example, with `DATETIME YEAR TO MINUTE`: startUnit = YEAR length = 12 (YYYYMMDDhhmm) endUnit = MINUTE
`java.lang.String toString()`	Converts the `DATETIME` value to a String object representing a datetime in the format `YYYY-MM-DD hh:mm:ss.fff`.
`static FglDateTime valueOf( long milliseconds)`	Creates a new `FglDateTime` object representing the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.
`static FglDateTime valueOf( java.lang.String val)`	Creates a new `FglDateTime` object from a String object representing a datetime value in the format: `YYYY-MM-DD hh:mm:ss.fff`
`static FglDateTime valueOf( java.lang.String val, int startUnit, int endUnit)`	Creates a new `FglDateTime` object from a String object representing a datetime value in the format `YYYY-MM-DD hh:mm:ss.fff`, using the qualifiers passed as parameter.

In the Java code, you can convert the com.fourjs.fgl.lang.FglDateTime to a java.util.Calendar object as in this example:

public static void useDatetime(FglDateTime dt) throws ParseException {
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
   Calendar cal = Calendar.getInstance();
   cal.setTime( sdf.parse(dt.toString()) );
   ...
}

If you need to create a com.fourjs.fgl.lang.FglDateTime object in your program, you can use the valueOf() class method as in this example:

IMPORT JAVA com.fourjs.fgl.lang.FglDateTime
MAIN
  DEFINE dt com.fourjs.fgl.lang.FglDateTime
  LET dt = FglDateTime.valueOf("2008-12-23 11:22:33.123")
  LET dt = FglDateTime.valueOf("11:22:33.123",
                FglDateTime.HOUR, FglDateTime.FRACTION3)
  DISPLAY dt.toString()
END MAIN

The valueOf() method expects a string representing a complete date-time specification, from year to milliseconds, equivalent to a DATETIME YEAR TO FRACTION(3) data type.