Missing Digit Solution

Main.java

import java.util.*;

public class Main {
    public static String MissingDigit(String str) {
        String[] newStr = new String[2];
        char op = 'c';
        String resultValue = "";

        str = str.replace(" ", "");
        if (str.contains("+")) {
            resultValue = str.split("=")[1];
            newStr = str.split("=")[0].split("\\+");
            op = '+';
        } else if (str.contains("-")) {
            resultValue = str.split("=")[1];
            newStr = str.split("=")[0].split("-");
            op = '-';
        } else if (str.contains("*")) {
            resultValue = str.split("=")[1];
            newStr = str.split("=")[0].split("\\*");
            op = '*';
        } else if (str.contains("/")) {
            resultValue = str.split("=")[1];
            newStr = str.split("=")[0].split("/");
            op = '/';
        }

        String result = "";
        int index = 0;
        if (newStr[0].contains("x")) {
            result = findResult(Integer.parseInt(resultValue), Integer.parseInt(newStr[1]), op, true);
            index = newStr[0].indexOf('x');
        } else if (newStr[1].contains("x")) {
            result = findResult(Integer.parseInt(resultValue), Integer.parseInt(newStr[0]), op, true);
            index = newStr[1].indexOf('x');
        } else {
            result = findResult((Integer.parseInt(newStr[0])), (Integer.parseInt(newStr[1])), op, false);
            index = resultValue.indexOf('x');
        }

        return String.valueOf(result.charAt(index));
    }

    public static String findResult(int num1, int num2, char op, boolean isInverse) {
        String result = null;
        switch (op) {
            case '+' -> {
                if (isInverse) result = Integer.toString(num1 - num2);
                else result = Integer.toString(num1 + num2);
            }
            case '-' -> {
                if (isInverse) result = Integer.toString(num1 + num2);
                else result = Integer.toString(num1 - num2);
            }
            case '*' -> {
                if (isInverse) result = Integer.toString(num1 / num2);
                else result = Integer.toString(num1 * num2);
            }
            case '/' -> {
                if (isInverse) result = Integer.toString(num1 * num2);
                else result = Integer.toString(num1 / num2);
            }
        }

        return result;
    }

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.print(MissingDigit("1x0 * 12 = 1200"));
    }
}