Convert hex string to byte []

Convert hex to byte and byte to hex.

public static byte[] hexStringToByteArray(String s) {                int len = s.length();                byte[] data = new byte[len/2];                for(int i = 0; i < len; i+=2){                    data[i/2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));                }                return data;            }final protected static char[] hexArray = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};public static String byteArrayToHexString(byte[] bytes) {            char[] hexChars = new char[bytes.length*2];            int v;            for(int j=0; j < bytes.length; j++) {                v = bytes[j] & 0xFF;                hexChars[j*2] = hexArray[v>>>4];                hexChars[j*2 + 1] = hexArray[v & 0x0F];            }            return new String(hexChars);        }

If we want to convert hex to byte array, we should make sure that hex string length should be of even length. Below method handles this

public static byte[] hexToByteArray(String hex) {    hex = hex.length()%2 != 0?"0"+hex:hex;    byte[] b = new byte[hex.length() / 2];    for (int i = 0; i < b.length; i++) {        int index = i * 2;        int v = Integer.parseInt(hex.substring(index, index + 2), 16);        b[i] = (byte) v;    }    return b;}