Passing Java objects to functions

Java objects must be instantiated and referenced by a program variable. The object reference is stored in the variable and can be passed as a parameter or returned from a program function. The Java objects are passed by reference to functions. This means that the called function does not get a clone of the object, but rather a handle to the original object. The function can then manipulate and modify the original object provided by the caller:

IMPORT JAVA java.lang.StringBuffer

MAIN
  DEFINE x java.lang.StringBuffer
  LET x = StringBuffer.create()
  CALL change(x)
  DISPLAY x.toString()
END MAIN

FUNCTION change(sb)
  DEFINE sb java.lang.StringBuffer
  CALL sb.append("abc")
END FUNCTION

Similarly, Java object references can be returned from functions:

IMPORT JAVA java.lang.StringBuffer

MAIN
  DEFINE x java.lang.StringBuffer
  LET x = build()
  DISPLAY x.toString()
END MAIN

FUNCTION build()
  DEFINE sb java.lang.StringBuffer
  LET sb = StringBuffer.create()   -- Creates a new object.
  CALL sb.append("abc")
  RETURN sb  -- Returns the reference to the object, not a copy/clone.
END FUNCTION