Simple Expression

import java.math.BigDecimal;
import java.util.Scanner;

public class _03_SimpleExpression {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);

        String initial = input.nextLine().replace(" ", "");

        String[] numbers = initial.split("(-)|(\\+)");
        String[] operations = initial.split("[.\\d]+");

        int startIndex = 0;
        if (operations[0] == "") {
            startIndex++;
        }

        BigDecimal sum = new BigDecimal(0);
        char currentOperation = '+';


        for (int j = 0; j < numbers.length; j++) {
            BigDecimal num = new BigDecimal(numbers[j]);

            if (currentOperation == '+') {
                sum = sum.add(num);

            } else {
                sum = sum.subtract(num);
            }

            startIndex++;

            if (startIndex <= operations.length - 1) {
                currentOperation = operations[startIndex].charAt(0);
            }

        }


        System.out.println(sum);
    }
}