Re: Help with BCD conversion
HarishD wrote:
Lew wrote:
Roedy Green wrote:
[snip]
The code OP presented with case clauses is fundamentally incorrect in
that it treats each of the cases as different. They are not, and
should be handled by the same code.I think that is mainly why everyone
has been reluctant to delve into it.
Amen to that.
--
Lew
Please don't quote sigs.
Thanks everyone for trying to help me. The reason I was going about
the conversion the way I was is due to the underlying code I am
constrained to use. The abstract class that does the transmission
requires a String. The vendor requirement was for certain fields to be
BCD encoded and some to EBCDIC. During the conversion of the byte
array to String a particular byte pattern (0x90) would get transformed
(to 0x3F). Fortunately I was able to override a method and was able to
Java 'String' doesn't hold bytes.
manually fix this transformation before transmission.
Congratulations on your creation of a solution.
A few notes to bear in mind for future reference, and for other readers, on
matters sometimes overlooked.
Conversion between byte array and Java 'String' is fraught with peril. There
are a plethora of 'String' encodings already, and you add BCD and EBCDIC.
Point zero - see Point three.
Point one - there are libraries out there, one wagers. Have you looked about?
Even should there be, it's not all that hard a problem that you would resist a
custom solution out of hand.
Point two - Isolate your encodings from each other, converting not between
each other but to a single /lingua franca/ encoding. Happily, Java 'String'
already provides that central encoding, likewise 'StringBuilder'.
Point three - *explicitly* control the 'byte'-'String[Builder]' encoding.
Don't leave it up to anyone's default. This is the single most important
point, so let's also call it Point zero. (Going back in time to add Point
zero. Done.)
Point four - Your data are character sequences. Your posts bespeak a focus on
bytes. Bytes are likely not the most effective model.
Point five - 0x90 is an 'int' constant. Quiz: sign extended?
Corollary: There is nothing to fear from signed bytes but your own
carelessness. Yeah, yeah, yeah - whatever, Java left out unsigned bytes. They
were wrong to do so. Let's all be whiny crybabies over it.
Lesson: You have to know what the frak you're doing. Control it. Don't guess.
Point six - There are always subtleties.
--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg