Java loop- keeps on asking for user input

Question

I looked at some other similar posts but was not able to figure out the solution, hence looking for your valuable input, thanks in advance.

What I want: You will be asked to enter a sign (+ , -, /) and the output will display "You entered minus" (if your input was -)

Class that takes the input

import java.util.Scanner;

public class TakeSign {
    Scanner userInput = new Scanner(System.in); /*Create an object of scanner class*/

    public char mySign() { 
        System.out.print("Enter a sign: ");
        char input2 = userInput.next().charAt(0);
        return input2;
    }
}

Main Class

public class Main {
    public static void main (String[]args) {
        TakeSign ts = new TakeSign();
        if (ts.mySign() == '+') {
            System.out.println("You entered plus");
        }
        else if (ts.mySign() == '-') {
            System.out.println("You entered minus");
        }
        else if (ts.mySign() == '/') {
            System.out.println("You entered division");
        }
    }
}

Problem

If my 1st input is / (division) I get asked 3 times. I was expecting to be asked just 1 time.

Enter a sign: /
Enter a sign: /
Enter a sign: /
You entered division

I think the problem is in the loop which I probably did not write correctly. Can you please point me to right direction?

austin wernli · Accepted Answer · 2015-01-15 19:36:56Z

4

You need to assign ts.mySign() to a variable and use that variable in your if statements

public static void main(String[] args) {
    TakeSign ts = new TakeSign();
    char sign = ts.mySign();
    if (sign == '+') {
        System.out.println("You entered plus");
    } else if (sign == '-') {
        System.out.println("You entered minus");
    } else if (sign == '/') {
        System.out.println("You entered division");
    }
}

answered Jan 15, 2015 at 19:36

austin wernli

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Comments

Dawood ibn Kareem · Accepted Answer · 2015-01-15 19:35:54Z

2

The mySign method asks the user for input. So if you call ts.mySign() three times, it will ask the user three times. But this is what you're doing in your chain of if and else statements.

You need to call ts.mySign() just once before the if statements, assign the result to a variable, then just check the value of that variable in each of the if statements.

answered Jan 15, 2015 at 19:35

Dawood ibn Kareem

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1 Comment

Sheikh Rahman Over a year ago

Thank You that explains the problem.

laune · Accepted Answer · 2015-01-15 19:39:29Z

1

You might use

 switch( ts.mySign() ){
 case '+':
     System.out.println ("You entered plus");
     break;
 case '-':
     System.out.println ("You entered mimus");
     break;
 case '*':
     System.out.println ("You entered asterisk");
     break;
 case '/':
     System.out.println ("You entered slash");
     break;
 default:
     System.out.println ("Input error");
     break;
}

answered Jan 15, 2015 at 19:39

laune

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Comments

Coding Enthusiast · Accepted Answer · 2015-01-15 20:14:27Z

0

You're calling ts.mySign() 3 times in your if-statement.

Call it once and store it in a variable and then compare against your signs.

i.e.

char sign = ts.mySign();
if (sign == '+')
...

edited Jan 15, 2015 at 20:14

Coding Enthusiast

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answered Jan 15, 2015 at 19:37

Amber

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