如何在java中将字符串转换为bcd格式的字节数组？

Question

I have the next string:

String points = "210987654321";

and I need to end up in the 6 byte array in bcd format which looks like this (same digits):

byte [] result = { 0x21, 0x09, (byte) 0x87, 0x65, 0x43, 0x21 };

How do I get there? points.getBytes(); gives not what I need.

Answer 1

Based on the code you provided and its expected output it looks like you're trying to convert into the BCD format (BCD is a rather generic definition) normally used to represent a string in which each letter represents a HEX digit into its corresponding byte representation (from comments to this answer: "packed BCD").

There are solutions in StackOverflow, such as the following:

• Convert a string representation of a hex dump to a byte array using Java?

In the interest of "not reinventing the wheel", however, I would favour functionality available in libraries like Apache Commons or Google Guava:

• https://commons.apache.org/proper/commons-codec/apidocs/org/apache/commons/codec/binary/Hex.html
• https://guava.dev/releases/16.0/api/docs/com/google/common/io/BaseEncoding.html

For Apache Commons it boils down to roughly this code:

byte[] result = Hex.decodeHex(points)

It is to be noted however that the above code will accept as inputs also strings containing letters up to the letter "F" so if that's not acceptable to you, you will have to make sure that your string only contains numbers.

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As BCD comprises a number of variants, I believe it's worth mentioning that before applying a BCD conversion you should determine which specific conversion you want to apply based on your software's purposes.

In the financial/services sector, for example, it's very common the need to convert into the EBCDIC format ( http://ascii-table.com/ebcdic-table.php ) to interact with IBM systems. In such case I recommend checking the following StackOverflow question and its related answers:

• Convert String from ASCII to EBCDIC in Java?

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Finally, if you really meant converting into another BCD format, you may have write your own code based the rules governing your specific BCD format. Before you start coding, of course, I still recommend looking for libraries performing the conversion for you.