Question

I want to pattern the string like this:

letters (in here there may be letters, numbers and whitespace)

I have try for this but it doesn’t work.

Scanner cin = new Scanner(System.in);
String format = "^[a-zA-Z]* ([a-zA-Z_0-9\\s]*)$";
String userInput = cin.nextLine();
if (userInput.matches(format)) {
   System.out.println("Correct Patten");
} else {
   System.out.println("Incorrect Pattern");
}

Thanks in advance…

Answer 1

Some characters in regex has special meaning, parenthesis is one of them. For them ot be interpreted as a character you need to escape them with a backslash, and since backslash has a special meaning in java strings you need to escape that with a backslash (for a total of two).

So your regex should be

String format = "^[a-zA-Z]* \\([a-zA-Z_0-9\\s]*\\)$";