title: Try/catch not working with android expression parser exp4j
body: <p>I am using the following bit of code to parse a string equation into a resulting double (based on some input values of doubles x, y and z and an equation input.). The program works fine when I run it as a java program in eclipse, however it hangs when I run it with in an android app (the app becomes unresponsive). In my app, I'm getting the string equation from a textbox and displaying the result number. Can anybody tell me why the following code doesn't work in android? My guess is that it has to do with the try-catch, but I can't figure out why. I'm using the exp4j jar.</p>
  
  <p>Thanks very much!</p>
  
  <pre><code>public class ParseEquation {
  
      public double totalValue = 0;
  
      public ParseEquation(String inputEquation, double x, double y,double z) 
      {   
          //String inputEquation = "-4.14*x*x - 5/2 - y^2";
          Calculable calc = null;
          try {
              calc = new ExpressionBuilder(inputEquation)
                  .withVariable("x", x)
                  .withVariable("y", y)
                  .withVariable("z", z)
                  .build();
          } catch (UnknownFunctionException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          } catch (UnparsableExpressionException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
  
          totalValue=calc.calculate();
      }   
  }
  </code></pre>