Question

I have a byte array I want to assign as follows:

• First byte specifies the length of the string: (byte)string.length()
• 2nd – Last bytes contain string data from string.getBytes()

Other than using a for loop, is there a quick way to initialize a byte array using bytes from two different variables?

Answer 1

You can use System.arrayCopy() to copy your bytes:

String x = "xx";
byte[] out = new byte[x.getBytes().length()+1];
out[0] = (byte) (0xFF & x.getBytes().length());
System.arraycopy(x.getBytes(), 0, out, 1, x.length());

Though using something like a ByteArrayOutputStream or a ByteBuffer like other people suggested is probably a cleaner approach and will be better for your in the long run 🙂