how to call function in Java?

How can I allow the end user to make a function in Java?

• I am making a GUI in Java that needs to allow the end user to create (many) functions of a strictly mathematical variety. For now we can restrict ourselves to functions of one variable. So let's say that there's a pad of buttons with built-in functions and symbols such as + - * / ( ) ln() exp() et cetera, you get the idea. And the user creates a function, say f(x) = (x+1)/(x-1) Now ignoring difficulties like division by zero and things such as that, how would I store this function and then call it when the time comes? Should I create a Function class of my own? How would it work? Any ideas are valued. You don't need to post actual code; I can figure it out if you can give me an idea of where to go with this.

• Answer:

  I would create a Function object class, which stores the function in postfix (reverse polish) notation, in a queue. If you are not familiar with postfix notation, here's the Wikipedia article on it: http://en.wikipedia.org/wiki/Reverse_Polish_notation Postfix notation is nice because, once it's in postfix notation, it's easy to handle. You can just dequeue it and operate as you progress. For information on convert to postfix: http://scriptasylum.com/tutorials/infix_postfix/algorithms/infix-postfix/index.htm