Question

This is my code…

class info{
    public static void main (String[]args) throws IOException{
        char gen;

        while(true) {   //problem occurs with this while
            System.out.print("\nENTER YOUR GENDER (M/F) : ");
            gen=(char)System.in.read();

            if(gen=='M' || gen=='F' || gen=='m' || gen=='f'){
                break;
            }
        }

        System.out.println("\nGENDER = "+gen);
    }
}

This is my output…

ENTER YOUR GENDER (M/F) : h

ENTER YOUR GENDER (M/F) :
ENTER YOUR GENDER (M/F) :
ENTER YOUR GENDER (M/F) : m

GENDER = m

Could someone please help me understand why it is asking for the gender so many times.

Answer 1

You are probably workin’ on Windows. When you give an answer and hit enter it adds two extra characters '\r' and '\n'. From stdin you receive only one character but those extra two remain in the buffer. When you give an incorrect answer you loop and automatically read from the buffer those two characters. They don’t match the gender so the loop continues. The best solution would be to analyze strings instead of characters:

InputStreamReader converter = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(converter);
String s = in.readLine();

Remember to use equals method instead of == in string comparison.