Each 2 Digit to Hexadecimal Byte Sequence

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Conversion {
  public static void main(String[] args) {
    List<Byte> ret = new ArrayList<Byte>();
    String s = "1234567890abcdef01234567890abcdef";
    Pattern p = Pattern.compile("..");
    Matcher m = p.matcher(s);
    while (m.find()) {
      char[] cs = m.group().toCharArray();
      int d = 0;
      for (int i = 0; i < cs.length; i++) {
        d = d * 16 + Character.digit(cs[i], 16);
      }
      ret.add((byte )d);
    }
    System.out.println(Arrays.toString(ret.toArray()));
  }
}