multiple variable for if else statement

Question

I have written some code to check if the user has entered a number between 1 and 5, and now I would also like my code to allow the user to enter the letters A, S, D or M.

Is there a way to combine the code where I can have it identify whether the user has entered 1-5 or A, S, D, M?

How do I edit the code below so the user can enter either an Integer or a character? Do I have to write a snippet of code underneath the loop for it to identify that a user did not enter 1-5 but did enter A, S, D, or M, as in break out of the loop? Or is it a separate loop all together. I am so confused!

import java.util.InputMismatchException;
import java.util.Scanner;

public class Selection {
    Scanner readInput = new Scanner(System.in);

    int selectionOne() {
        int inputInt;
        do { //do loop will continue to run until user enters correct response
            System.out.print("Please enter a number between 1 and 5, A for Addition, S for subtraction, M for multiplication, or D for division: ");
            try { 
                inputInt = readInput.nextInt(); //user will enter a response
                if (inputInt >= 1 && inputInt <=5) {
                    System.out.print("Thank you");
                    break; //user entered a number between 1 and 5
                } else {
                    System.out.println("Sorry, you have not entered the correct number, please try again.");
                }
                continue;
            }
            catch (final InputMismatchException e) {
                System.out.println("You have entered an invalid choice. Try again.");
                readInput.nextLine(); // discard non-int input
                continue; // loop will continue until correct answer is found
            }
        } while (true);
        return inputInt;
    } 
}

Answer 1

I suggest instead of using an int input, just use a String input and convert it to an integer when you need to. You can use Integer.parseInt(String) to convert a String to an int .

So when you check if the input is valid, you need to check if the input is equal to "A" , "S" , "M" or "D" , or any values from 1-5 when it is converted to an int .

So to check if it's one of the characters, you could do this:

if (input.equals("A") || input.equals("S") || input.equals("M") || input.equals("D"))

And then to test if it's an int of value 1 through 5, you could do this:

if (Integer.parseInt(input) >= 1 && Integer.parseInt(input) <= 5)

Just parse the input to an int and then check the range as you already have done.

The return type of this method will be String now, instead of int . If you need it to be an int for whatever reason, you can just parse the value to an int and then return that instead. But I just returned it as a String .

The last thing I changed was the catch block. Now, instead of an InputMismatchException (because they can enter String s now, I changed it to NumberFormatException , which would happen if a String that could not be converted to an int was attempted to be. For example, Integer.parseInt("hello") will throw a NumberFomatException because "hello" can not be represented as an integer. But, Integer.parseInt("1") would be fine and would return 1 .

Note that you should test the String equivalence first so that you don't go into your block before you have a chance to test all conditions you need to.

The method would look like this:

String selectionOne() {
    String input;
    do { //do loop will continue to run until user enters correct response
        System.out.print("Please enter a number between 1 and 5, A for Addition, S for subtraction, M for multiplication, or D for division: ");
        try { 
            input = readInput.nextLine(); //user will enter a response
            if (input.equals("A") || input.equals("S") || input.equals("M") || input.equals("D")) {
                System.out.println("Thank you");
                break; //user entered a character of A, S, M, or D
            } else if (Integer.parseInt(input) >= 1 && Integer.parseInt(input) <= 5) { 
                System.out.println("Thank you");
                break; //user entered a number between 1 and 5
            } else {
                System.out.println("Sorry, you have not entered the correct number, please try again.");
            }
            continue;
        }
        catch (final NumberFormatException e) {
            System.out.println("You have entered an invalid choice. Try again.");
            continue; // loop will continue until correct answer is found
        }
    } while (true);
    return input;
}

Answer 2

As @MarsAtomic mentioned, first thing you should change your input to String instead of an int so you can easily handle both characters and digits.

Change:

int inputInt;

To:

String input;

Then change:

inputInt = readInput.nextInt();

To:

input = readInput.next();

To accommodate reading String instead of int .

Now you reach at 2 main cases (and 2 subcases):

1) input is a single character
   a) input is a single digit from 1-5
   b) input is a single character from the set ('A', 'S', 'D', 'M')
2) input is an error value

Also, since you are not calling Scanner.nextInt , you don't need to use the try/catch statement and can print your errors in else blocks.

Furthermore, you should have your method return a char or a String instead of an int so you can return both 1-5 or A,S,D,M . I will assume you want to return a char . If you want to return a String instead, you can return input instead of return val in the code bellow.

NOTE: The code bellow can be simplified and shortened, I just added variables and comments in an attempt to make each step clear to what is being read or converted. You can look at @mikeyaworski's answer for a more concise way of doing this.

Here is how your code could look like:

   char selectionOne() {
        String input;
        do {
            input = readInput.next();
            // check if input is a single character
            if(input.length() == 1) {
                char val = input.charAt(0);
                // check if input is a single digit from 1-5
                if(Character.isDigit(val)) {
                    int digit = Integer.parseInt(input);
                    if (digit >= 1 && digit <=5) {
                        System.out.print("Thank you");
                        return val; // no need to break, can return the correct digit right here
                    } else {
                        System.out.println("Sorry, you have not entered the correct number, please try again.");
                    }
                } else {
                    // check if input is in our valid set of characters
                    if(val == 'A' || val == 'S' || val == 'M' || val == 'D') { 
                        System.out.print("Thank you");
                        return val;  // return the correct character
                    } else {
                        System.out.println("Sorry, you have not entered the correct character, please try again.");
                    }
                }
            } else {
                System.out.println("Sorry, you have not entered the correct input format, please try again.");
            }
        } while(true);
    } 

Answer 3

If your input can be both characters and letters, why not change to looking for a char or String? Then, you can look for "1" or "A" without any trouble.