CAST

The CAST operator converts a Java object to the user-defined type or Java class specified.

Syntax

CAST( obj AS type )

obj is a Java object.
type is a user-defined type or a Java class.

Usage

The CAST() operator is required when you want to assign an object reference to variable defined with a user-defined type or Java class which requires narrowing reference conversion.

Example

In this example, when assigning a java.lang.StringBuffer reference to a java.lang.Object variable, widening reference conversion occurs and no CAST() operator is needed, but when assigning an java.lang.Object reference to a java.lang.StringBuffer variable, you must cast the object reference to a java.lang.StringBuffer:

IMPORT JAVA java.lang.Object
IMPORT JAVA java.lang.StringBuffer
MAIN
  DEFINE sb1, sb2 java.lang.StringBuffer 
  DEFINE o java.lang.Object 
  LET sb1 = StringBuffer.create()
  LET o = sb1 -- Widening Reference Conversion does not need CAST()
  LET sb2 = CAST( o AS java.lang.StringBuffer ) -- Narrowing 
                  -- Reference Conversion needs CAST()
END MAIN

In order to cast an fgl.FglRecord object to a regular RECORD, you need to specify a user-defined type (TYPE definition):

IMPORT JAVA com.fourjs.fgl.lang.FglRecord
TYPE mytype RECORD f1, f2 INTEGER END RECORD
MAIN
  DEFINE r mytype
  DEFINE jr fgl.FglRecord
  LET jr = r
  LET r = CAST(jr AS mytype)
  -- This is denied:
  --   CAST(jr AS RECORD f1, f2 INTEGER END RECORD)
END MAIN