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 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
String toString()	Converts the `DATETIME` value to a String object representing a datetime in the format `YYYY-MM-DD hh:mm:ss.fff`.
static void valueOf( 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 void valueOf( 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.
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

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 an 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.