Do while Running more times

Question

I have to get 1 to 3 answer if user puts invalid option do while should re run but problem is its re running three times. like if I put answer in 1 to 3 its giving correct result on other number it reprint loop three times.

char choice;
public void mainMartfunc() throws java.io.IOException{

        do{
            System.out.println("Login as:");
            System.out.println("    1. Customer");
            System.out.println("    2. Employee");
            System.out.println("    3. Owner");
            choice = (char) System.in.read();
            } while(choice < '1' || choice>'3');
        switch(choice){

         case '1':
             System.out.println("\tCustomer Menu:");
             break;

         case '2':
             System.out.println("\tEmployee Menu:");
             break;

         case '3':
            System.out.println("\tOwner Menu:");
            break;
        }
}

What do you think `System.in.read` does and why do you think so? — Sotirios Delimanolis, Jan 19 '15 at 18:13
I read in complete reference Java, if you have to print menu this is best option thats why i implemented it — maniarali, Jan 19 '15 at 18:20

score 2 · Accepted Answer · answered Jan 19 '15 at 18:19

2

When you press the enter key, two characters are generated: a carriage return '\r' and a line feed '\n'. And System.in.read() takes each character from the input, so you get three characters including the digit.

Trying using a Scanner instead. It will tokenize your input so you don't receive those whitespace characters.

java.util.Scanner input = new java.util.Scanner(System.in);

then change your choice assignment to something like this:

choice = input.next().charAt(0);

answered Jan 19 '15 at 18:19

gknicker

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Very good explanation. Many do not realize the extra characters enter the input stream. – Zéychin Jan 19 '15 at 18:22
This have sort out my problem – maniarali Jan 19 '15 at 18:28

Do while Running more times

1 Answers1