LegacyJ FAQ

Calls between COBOL and Java

Question: "We would like more information about implementing CALLS between the PERCobol compiled programs and our own hand crafted Java.  The issue concerns how we should code the inclusion of a packed decimal number in a parameter string. Our Cobol programs send parameters in a single block - this is constructed and de-constructed into individual fields within each program.  These fields have datatypes of their own right such as string, zoned and packed".

Passing numerics between COBOL and Java with  PERCobol:

Here is some information on how VS Cobol II (AIX/ASCII) stores numbers:

http://www-3.ibm.com/software/awdtools/cobol/library/booksghi/Igya1mst.pdf
Go to page 29 ( pdf page 55 )

This pdf and others are available at:
http://www-3.ibm.com/software/awdtools/cobol/aix/library/

Also, attached is a snippet of code that may help you get started.

The attached snippet is for storing a string into a byte[] and int offset.  You'll need to understand the variable into which it's being placed, its picture (PIC S999V99 for instance, stripped to 99999 for even/odd purposes here), its sign (the implicit SIGN TRAILING, SIGN LEADING, etc.), and its size in bytes (itemSize, the number of bytes the packed-decimal uses; the listing file will have this information if you don't know it.  In general, number of 9's plus one for sign, divided by two and rounded up if necessary).  (The Cobol programmers will be well aware of these concepts.)

This takes care of a number of cases, so if a case is known never to occur, it may be stripped away; the sign leading and trailing are done in separate areas, for instance.

Additional Tips

An easy method for passing data back and forth from Java to COBOL is by using the GET-PROPERTY, SET-PROPERTY feature:

WORKING-STORAGE SECTION.

01 my-outer-array occurs 3 times.
     05 my-array occurs 5 times pic x(10) is get-property
            set-property.

Then use:

cobolObj.setMyArray(1,1,"Hello");

or

String result=cobolObj.getMyArray(1,1);