import java.util.*;
import java.util.Arrays;

public class OAAusdruckParser {

    public static void main(String[] args) {
        String inputString = "2 * 3 + 4 * 7";
        String inputArray[] = inputString.split(" ");

        List<String> operators = Arrays.asList("+", "*", "-", "/", "(", ")");

        Stack<String> operatorsStack = new Stack();
        Stack<Double> numbersStack = new Stack();

        operatorsStack.push("(");
        numbersStack.push(0.0);

        double currentNumber;
        String currentOperator;

        double x;
        double y;
        String o;

        for (String value : inputArray) {
            //System.out.println(value);

            if (operators.contains(value)) {

                if (value.equals("+") || value.equals("-") && operatorsStack.size() >= 2 && numbersStack.size() >= 2) {
                    x = numbersStack.pop();
                    y = numbersStack.pop();
                    o = operatorsStack.pop();

                    switch (o) {
                        case "*":
                        case "/":
                            numbersStack.push()

                            break;
                    }
                }

                operatorsStack.push(value);
            } else {
                currentNumber = Double.parseDouble(value);

                numbersStack.push(currentNumber);
            }
        }

        System.out.println(Arrays.toString(numbersStack.toArray()));
        System.out.println(Arrays.toString(operatorsStack.toArray()));
    }

}