Regex in Java with method matches

Question

I don't understand why the output is false in this case:

public class Enhanced {
    static String[] input = {"A","B","C"};
    public static void main(String[] args){
        System.out.println(input[0].matches("^[RK]"));
    }
}

I thought it would be true because 'A' is neither 'R' nor 'K'.

Answer 1

^[RK]

^ assert position at start of the string

[RK] matches letter R and K

You probably want to try this :

[^RK]

[^RK] matches a single character other than R or K