Writing code that doesn't contain Roman Numerals

Question

I am writing code for an assignment an it must follow these guidelines: /* returns true if s consists only of letters that * are also Roman numerals */

I have written code that looks like this:

if (!s.contains("I") || !s.contains("V") || !s.contains("X") || 
!s.contains("L") || !s.contains("C") || !s.contains("D") || !s.contains("M") 
|| !s.contains("i") || !s.contains("v") || !s.contains("x") || 
!s.contains("l") || !s.contains("c") || !s.contains("d") || 
!s.contains("m")) {
        return false;
    } else{
        return true;
    }

}

This looks like it would work but it does not. Help would be appreciated!

Answer 1

Put the characters into a list and check if that list contains the character your checking. This is way cleaner and better maintainable. Now just run the string into a forloop. If you find a character that is roman break and return false..otherwise return true.

public static boolean checkRomanNums(String s){
    List<Character> romanNumerials=Arrays.asList('I','V','X','L','C','D','M');
    for(int i=0;i<s.length();i++){
        if(romanNumerials.contains(s.charAt(i))){
           return false;
        }
    }
    return true;
}

Answer 2

你应该使用类似return s.matches("(?i)[ivxlcdm]+");

Answer 3

public static boolean containsOnlyRomanNumerals(String s) {
  return s.matches("[IVXLCDMivxlcdm]*");
}

This should do the trick. The regular expression checks if s consists only of the characters in the square brackets.