public class CalculatorParser {
    public static int evaluate(String text) {
        int result;

        String [] tab = text.split( " " );
        int firstNumber = Integer.parseInt( tab[0] );
        int secondNumber = Integer.parseInt( tab[2] );

        if(tab[1].equals( "+" ))
        {
            result = firstNumber + secondNumber;
        }

        else if(tab[1].equals( "-" ))
        {
            result = firstNumber - secondNumber;
        }

        else if(tab[1].equals( "*" ))
        {
            result = firstNumber * secondNumber;
        }

        else
        {
            result = firstNumber / secondNumber;
        }

        return result;
    }

    public static void main(String[] args) {
        System.out.println("Wynik operacji 2 + 2: " + evaluate("2 + 2"));
        System.out.println("Wynik operacji 5 - 3: " + evaluate("5 - 3"));
        System.out.println("Wynik operacji 8 * 2: " + evaluate("8 * 2"));
        System.out.println("Wynik operacji 20 / 4: " + evaluate("20 / 4"));
    }
}