How to catch an error inside the expression and avoid software to crash

[Megabyte94]

I am using EvalEx in my Android calculator app that I am currently developing. But if user writes any expression that is incorrect (like, for example, "3+*5"), the app crashes and gets closed because obviously, EvalEx cannot solve incorrect expressions. But I would like my app not to crash every time user makes a mistake, I want my app to show an error (like any other calculator app does) instead, but first of all, I have to know how to detect errors. How could I do that? Thanks.

[uklimaschewski]

Do as you do with any other code in Java: Check for exceptions:

    Expression e = new Expression("3+*5)");
    try {
      BigDecimal result = e.eval();
    } catch (ExpressionException ex) {
      System.out.print("Error: " + ex.getMessage());
    }

or if you want to catch everything: catch (Exception ex)

This will print out Error: Unknown unary operator * at character position 3

[Megabyte94]

Thank you very much!