String validations

Q: How to validate a string that contains characters other than alphabets, digits and some optional characters?

Assumption: Options characters here are:  -!@#$%^&*()_+|~-=\\’{

Answer:

String optonalChars = "-!@#$%^&*()_+|~-=\\’{";
String str = "pramod-!@#$%^&*()_+|~-=\\’{]";
for(int i = 0; i< str.length(); i++){
       char ch = str.charAt(i);
       if(!Character.isAlphabetic(ch) && ! Character.isDigit(ch) && optonalChars.indexOf(ch)<0){
             System.out.println("Invalid string");
             System.out.println("Invalid char is: " + ch);
             break;
       }
}
 
Output:
Invalid string
Invalid char is: ]