Java tutorial
//package com.java2s; //License from project: Apache License public class Main { public static byte[] ConvertStringToHexBytes(String StringToConvert) { StringToConvert = StringToConvert.toUpperCase(); StringToConvert = StringToConvert.replaceAll(" ", ""); char[] CharArray = StringToConvert.toCharArray(); char[] Char = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; int result = 0; byte[] ConvertedString = new byte[] { (byte) 0x00, (byte) 0x00 }; for (int i = 0; i <= 1; i++) { for (int j = 0; j <= 15; j++) { if (CharArray[i] == Char[j]) { if (i == 1) { result = result + j; j = 15; } else if (i == 0) { result = result + j * 16; j = 15; } } } } ConvertedString[0] = (byte) result; result = 0; for (int i = 2; i <= 3; i++) { for (int j = 0; j <= 15; j++) { if (CharArray[i] == Char[j]) { if (i == 3) { result = result + j; j = 15; } else if (i == 2) { result = result + j * 16; j = 15; } } } } ConvertedString[1] = (byte) result; return ConvertedString; } }