Implement String#hex_number? (in Java StringUtils.isHexNumber(String)), which should return true if given object is a hexadecimal number, false otherwise. Hexadecimal numbers consist of one or more digits from range 0-9 A-F (in any case), optionally prefixed by 0x.

StringUtils.java

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StringUtils {
  
  public static boolean isHexNumber(String s) {
     boolean b = false;
     if(s != null){
     Pattern p = Pattern.compile("^(0x)?[\\dA-Fa-f]+$");
     Matcher m = p.matcher(s);
     b =  m.matches();
     }
     return b;
  }
}

StringUtils.js

String.prototype.hexNumber = function() {
  return /^(0x)?[\da-f]+$/i.test(this);
};