IsValidHex.java

public class IsValidHex {
    public static boolean isValidHexMethod(String hex) {
        if (hex.length() != 7) return false; 
        if (hex.charAt(0)!='#') return false; 
        for (int i = 1; i<hex.length(); i++) {
            if (hex.charAt(i) != 'A' && hex.charAt(i) != 'B' && hex.charAt(i) != 'C' && hex.charAt(i) != 'D' && hex.charAt(i) != 'E' && hex.charAt(i) != 'F' &&
                hex.charAt(i) != 'a' && hex.charAt(i) != 'b' && hex.charAt(i) != 'c' && hex.charAt(i) != 'd' && hex.charAt(i) != 'e' && hex.charAt(i) != 'f' &&
                hex.charAt(i) != '0' && hex.charAt(i) != '1' && hex.charAt(i) != '2' && hex.charAt(i) != '3' && hex.charAt(i) != '4' && hex.charAt(i) != '5' &&
                hex.charAt(i) != '6' && hex.charAt(i) != '7' && hex.charAt(i) != '8' && hex.charAt(i) != '9') {
                    return false; 
                }
        }
        return true; 
    }
}