public class Main {
public static byte[] hexStringToByteArray(String s) {
byte[] b = new byte[s.length() / 2];
for (int i = 0; i < b.length; i++) {
int index = i * 2;
int v = Integer.parseInt(s.substring(index, index + 2), 16);
b[i] = (byte) v;
}
return b;
}
}