如何让程序显示吐司而不是崩溃？

Question

I am working on an app. Here's a small fragment which converts the entered string to a fraction:

public int[] fractionalize(String rawFraction1) {
        int[] result = {0,0,0};
        if (rawFraction1.contains("/") && !rawFraction1.contains(" ")){
            //normal fraction
            int a = Integer.parseInt(rawFraction1.split("/")[0]);
            int b = Integer.parseInt(rawFraction1.split("/")[1]);
            result = new int[]{a,b,0};
        } else if (rawFraction1.contains("/") && rawFraction1.contains(" ")){
            //mixed fraction
            int wholeNum = Integer.parseInt(rawFraction1.split(" ")[0]);
            int num = Integer.parseInt(rawFraction1.split(" ")[1].split("/")[0]);
            int den = Integer.parseInt(rawFraction1.split(" ")[1].split("/")[1]);
            result = new int[]{num, den, wholeNum};
        } else if (!rawFraction1.contains(" ") && !rawFraction1.contains("/")){
            int wholeNum = Integer.parseInt(rawFraction1);
        } else {
            Toast toast = Toast.makeText(getApplicationContext(), "The number you entered is in an invalid format. Please see the correct format to enter numbers.",Toast.LENGTH_LONG);
            toast.show();
        }
        return result;
    }

This works pretty well, provided you enter the number in the correct format. However, if we mess up the format, example, inserted 2 spaces or '/', the app crashes and closes. I want that if the program encounters a problem in this segment, it should show a toast instead and not close.

Is this possible? If yes, how?

Answer 1

You could check the string array length after splitting to show Toast. Another solution is use try/catch, and in catch block you show Toast (not recommend)

Answer 2

Just surround it with try/catch as easy as:

    public int[] fractionalize(String rawFraction1) {
        try {
            int[] result = {0, 0, 0};
            if (rawFraction1.contains("/") && !rawFraction1.contains(" ")) {
                //normal fraction
                int a = Integer.parseInt(rawFraction1.split("/")[0]);
                int b = Integer.parseInt(rawFraction1.split("/")[1]);
                result = new int[]{a, b, 0};
            } else if (rawFraction1.contains("/") && rawFraction1.contains(" ")) {
                //mixed fraction
                int wholeNum = Integer.parseInt(rawFraction1.split(" ")[0]);
                int num = Integer.parseInt(rawFraction1.split(" ")[1].split("/")[0]);
                int den = Integer.parseInt(rawFraction1.split(" ")[1].split("/")[1]);
                result = new int[]{num, den, wholeNum};
            } else if (!rawFraction1.contains(" ") && !rawFraction1.contains("/")) {
                int wholeNum = Integer.parseInt(rawFraction1);
            } else {
                Toast toast = Toast.makeText(getApplicationContext(), "The number you entered is in an invalid format. Please see the correct format to enter numbers.", Toast.LENGTH_LONG);
                toast.show();
            }
            return result;
        } catch (Exception e) {
            e.printStackTrace();
            Toast toast = Toast.makeText(getApplicationContext(), "Invalid Input.", Toast.LENGTH_LONG);
            toast.show();
        }
        return null;
    }