Here an other solution
public static String toHexString(byte[] ba) {
StringBuilder str = new StringBuilder();
for(int i = 0; i < ba.length; i++)
str.append(String.format("%x", ba[i]));
return str.toString();
}
public static String fromHexString(String hex) {
StringBuilder str = new StringBuilder();
for (int i = 0; i < hex.length(); i+=2) {
str.append((char) Integer.parseInt(hex.substring(i, i + 2), 16));
}
return str.toString();
}