Convert a double value to Packed decimal COBOL format PIC S9(5)V9(4) COMP-3/Packed decimal COBOL format PIC S9(3)V9(4) COMP-3 format in JAVA

Question

I am trying to convert a double value to Packed decimal COBOL format PIC S9(5)V9(4) COMP-3/Packed decimal COBOL format PIC S9(3)V9(4) COMP-3 format in JAVA, see below example :

Double Value : 00000.6775 Converted to Packed Decimal : ^@^FS,^@

Is this conversation possible in java?

Answer 1

Similar questions have been answered multiple times already on Stack overflow

For s9(5)V9(4) comp-3, 123.45 is represented in byte format as

00 12 34 50 0c

The C is the sign

Yes this is possible, the JRecord package will do it (may truncate extra digits though).

The approach is

• to Convert double to a unsigned and unscaled long / BigInteger i.e 123.45 --> 1234500 (for s9(5)v9(4))
• Convert the long to packed decimal

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At this point there are several approaches

• Repeatably Divide by 100 and use the remainder to lookup the byte value in a an array. See https://github.com/bmTas/JRecord/blob/master/Source/JRecord_Project/JRecord_Common/src/main/java/net/sf/JRecord/Types/smallBin/TypePackedDecimal9.java for an example
• Divide by by 10, use the remainder && shift 4 bit operator to create the answer
• Convert the number to a string, Add the sign char to the end and then **new BigInteger(UnscalledNumberAsString, 16).toByteArray() will do the conversion. See Conversion for an example