Where can I find code for converting Java data types to/from other data formats such as: EBCDIC, IBM370 COMP (binary numbers up to 9 digits), and COMP-16 (packed decimal numbers)?

You will have to use the java.io.InputStreamReader class. This can convert data in any encoding to Unicode as long as the right ByteToCharConvertor is available. Here are the supported encodings and some more info on Character Stream I/O.