The INSTANCEOF operator

When manipulating an object reference with a variable defined with a superclass of the real class used to instantiate the object, you sometimes need to identify the real class of the object.

This is possible with the INSTANCEOF operator.

This operator checks whether the left operand is an instance of the type or class specified by the right operand:

object_reference INSTANCEOF type_or_class

This example creates a java.lang.StringBuffer object, assigns the reference to a java.lang.Object variable, and tests whether the class type of the object reference is a java.lang.StringBuffer:

IMPORT JAVA java.lang.Object
IMPORT JAVA java.lang.StringBuffer
MAIN
  DEFINE o java.lang.Object
  LET o = StringBuffer.create()
  DISPLAY o INSTANCEOF StringBuffer    -- Shows 1 (TRUE)
END MAIN