Java solving mathematical operations from strings
<p>I have strange task to do in Java.
Without using any loops and if statements i have to develop simple calculator which defines all operations and numbers in one String like: "126.7214        +  121"
I used regex to parse string and get 3 string variables ['125.7214', '+' ,'121'], normally i would do if statement, parseString to integer and do if statement based on math symbol to sum those numbers, but I cant. Is there any trick in Java to do it faster? Some ready-to go library?
I would appreciate any advice. :code:</p>

<pre><code>import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class Calc {

    public String doCalc(String cmd) {

        Matcher m = Pattern.compile("\\S+").matcher(cmd);
        m.find();
        String num1= m.group(0);
        m.find();
        String znak = m.group(0);
        m.find();
        String num2 = m.group(0);





        return result;
    }
}  
</code></pre>