Java String, single char to hex bytes

Question

I want to convert a string by single char to 5 hex bytes and a byte represent a hex number:

like

String s = "ABOL1";

to

byte[] bytes = {41, 42, 4F, 4C, 01}

I tried following code , but Byte.decode got error when string is too large, like "4F" or "4C". Is there another way to convert it?

String s = "ABOL1";
char[] array = s.toCharArray();
for (int i = 0; i < array.length; i++) {
  String hex = String.format("%02X", (int) array[i]);
  bytes[i] = Byte.decode(hex);
}                

Solution 1

Use String hex = String.format("0x%02X", (int) array[i]); to specify HexDigits with 0x before the string.

A better solution is convert int into byte directly:

bytes[i] = (byte)array[i];

Solution 2

Is there any reason you are trying to go through string? Because you could just do this:

bytes[i] = (byte) array[i];

Or even replace all this code with:

byte[] bytes = s.getBytes(StandardCharsets.US_ASCII);

Solution 3

You can convert from char to hex String with String.format():

String hex = String.format("%04x", (int) array[i]);

Or threat the char as an int and use:

String hex = Integer.toHexString((int) array[i]);

Comments

[fge]

A char is not a byte!

[user207421]

There is no such thing as a 'hex byte'. The data is already in the format you require. Just copy the bytes.