Why can't I break a while loop in the main method with break keywords inside of one of the methods? What should I do instead?

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1

I wanted to loop my calculator in a manner similar to Codecademy’s Area Calculator. I embraced most of my methods with a while loop’s curly brackets

public static void main(String[] args) {
        Num firstNum = new Num();
        Num secondNum = new Num();

        System.out.println(getGreeting() + " I'm Alec the Calculator! I can perform the following operations: " +
                "addition (+), subtraction (-), multiplication (*), and division (/). But I'm only a beginner! " +
                "That's why I can only operate with integers of up to ten. Keep in mind, if you input more than two " +
                "operands, I will execute only the first operation and ignore the rest. The good news is you can " +
                "use both Arab (1, 2, 3...) and Roman numbers (I, II, III...)! ");

        while (true) {
            System.out.println("You can type in your math problem below:");

            Scanner scanner = new Scanner(System.in);
            firstNum.stringValue = scanner.next();
            stringOperation = scanner.next();
            secondNum.stringValue = scanner.next();

            firstNum.checkType();
            secondNum.checkType();

            if (firstNum.type == 'd' || secondNum.type == 'd') {
                firstNum.decimalRejection(firstNum, secondNum);
            }

            if (firstNum.type == 'i' || secondNum.type == 'i') {
                integerHandling(firstNum, secondNum);
            }

            if (firstNum.type == 'r' || secondNum.type == 'r') {
                romanHandling(firstNum, secondNum);
            }

            calculatingResult(firstNum, secondNum);
            
            printingResult(firstNum, secondNum);
        }
    }

and added several break keywords inside the printingResult() method. It’s always called. There should not be any infinite loops (to the best of my knowledge)!

public static void printingResult(Num firstNum, Num secondNum) {
        if (!(stringOperation.equals("/") && secondNum.doubleValue == 0)) {
            if (!dontKnow) {
                if (firstNum.type == 'r' && secondNum.type == 'r') {
                    if(result == 0){
                        System.out.println("Oops! It seems we got a zero – or \"nulla\", as Romans said. " +
                                "The Roman numeral system didn't have a zero, you see!");
                        break;
                    } else if(result < 0) {
                        System.out.println("Uh-oh... It looks like you subtracted more than you had in the first place! " +
                            "It's generally okay, but the problem is the Roman numeral system didn't have negative numbers");
                        break;
                    } else {
                        System.out.println("It's " + arabToRoman() + "!");
                        break;
                    }
                } else {
                    if (result != (int) result) {
                        if (String.valueOf(result).equals(df.format(result))) {
                            System.out.println("It's " + result + "! If you don't like decimals, here's your integer " +
                                    "answer: " + (int) result + ". I like decimals, though");
                            break;
                        } else {
                            System.out.println("It's approximately " + df.format(result) + "! " +
                                    "Or, if we choose to leave out the decimal part, it's " + (int) result);
                            break;
                        }
                    } else {
                        System.out.println("It's " + (int) result + "!");
                        break;
                    }

                }
            } else {
                break;
            }
        } else {
            if (!dontKnow) {
                System.out.println("Gosh! I tried to divide it by zero, as you requested, but my virtual head nearly " +
                        "exploded! I need to recover...");
                quit();
            } else {
                System.out.println("Besides, you can't even divide by zero, I'm so told!");
                break;
            }
        }
        }

However, my IntelliJ IDEA refuses to run the program because it doesn’t see those breaks as part of any loop of switch. What should I do?

2

You might change the function/method so that it returns something,
and then, in the loop, you could break out of the loop or not depending on what the function returned.

You may do that by returning false to indicate exiting the loop (meaning putting return false instead of break in the printingResult method, and return true at the end of that method).

And you could put an if-block with a break, or just change the while-loop condition to exit out of using what that method returned.

possibly something like

      boolean shouldContinueLoop = true;
        while (shouldContinueLoop) {
            // lots more code here
            
            shouldContinueLoop = printingResult(firstNum, secondNum);
        }
2 Likes
3

I already guessed it myself, but thanks (I did it a bit differently but more or less the way you suggested)! Consider checking my question about the DecimalFormat.format() method and the one about my println() printing a line twice!