Breaking It Down

// Breaking it down problem, too much was in main, broke it down
// Renee Waggoner
// June 24, 2019
// Special Requirements: None

package breaking_it_down;
import java.util.Scanner;

public class TooMuchInMain {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int operand1, operand2, answer;
        char operator='q';
        // highest priority for single calculation
        boolean keepCalculating = true;
        while (keepCalculating) {

            // calling operator for calculation with do calculation method with parameters
            operator = doCalculation(scan, operator);

            //  if true do this
            if (operator == 'q') {
                break;
            }
            int whichNumber;
            // assigning a value
            whichNumber = 1;
            System.out.println("Enter an operator: + - * / q for quit: " + whichNumber);
            String userInput;
            userInput = getOperandAndValidateThatItIsAValidNumber(scan);
            // storing user input
            operand1 = Integer.parseInt(userInput);

            whichNumber = 2;
            System.out.println("Enter operand " + whichNumber);
            userInput = getOperandAndValidateThatItIsAValidNumber(scan);

            operand2 = Integer.parseInt(userInput);

            answer = doArithmetic(operand1, operand2, operator);

            System.out.println(operand1 + " " + operator + " " + operand2 + " = " + answer);
            System.out.println("=======================");
        }
        // this is inside while loop here
        System.out.println("Finished Calculations");
        scan.close();
    }

    private static char doCalculation(Scanner scan, char operator) {
        boolean operator_is_good = false;

        do {
            System.out.print("Enter an Operator: + - * / q for quit: ");
            String strOperator = scan.nextLine();
            strOperator = strOperator.trim();
            if (strOperator.length() == 0)
                continue; // Need to try this again with no input
            operator = strOperator.charAt(0);
            operator_is_good = false;
            switch (operator) {
            case 'q':
            case '+':
            case '-':
            case '*':
            case '/':
                operator_is_good = true;
                break;
            default:
                System.out.println("Your operator is bad ... try again:");
                break;
            }
        } while (!operator_is_good);
        return operator;
    }

    private static int doArithmetic(int operand1, int operand2, char operator) {
        int answer;

        switch (operator) {
        // identifying each valid operator response from user
        case '+':
            answer = operand1 + operand2;
            break;
        case '-':
            answer = operand1 - operand2;
            break;
        case '*':
            answer = operand1 * operand2;
            break;
        case '/':
            answer = operand1 / operand2;
            break;
        default:
            System.out.println("We shouldn't get here in doArithmentic!!!!");
            answer = -1;
            break;
        }
        return answer;
    }

    private static String getOperandAndValidateThatItIsAValidNumber(Scanner scan) {
        boolean operand_is_bad;
        String input;
        do {
            // if user provides bad input
            operand_is_bad = false;
            input = scan.nextLine();
            // trims trailing and leading spaces from user input
            input = input.trim();
            if (input.length() == 0)
                operand_is_bad = true;
            for (int i = 0; i < input.length(); i++) {
                char c = input.charAt(i);
                // when left side is true, evaluate right side
                if (c < '0' || c > '9') {
                    operand_is_bad = true;
                    // prints when user gives a bad input
                    System.out.println("Your last input was bad, try again");
                }
            }
        } while (operand_is_bad);
        return input;
    }
}