Validating mathematical operations in Java

Question

I have a string containing a mathematical operation (programmatically generated), something like

(1000 + 700) * (50 + 25) = (10000 - 5000) // it's an example

I need a method that I have to pass this string to it, and it will return true if the operation is valid else it will return false. Any ideas on how can I achieve this?

if it was _programmatically_ generated, then it should be validated upon generate — Baby, Feb 07 '14 at 08:12
No @RafaEl it can't be validated because it is being generated as a String. — Shahe, Feb 07 '14 at 08:13
@Hanky웃Panky the seperators are not always a `=` it can differ, and how can I run the calculation on one side? — Shahe, Feb 07 '14 at 08:14
Refer this link http://stackoverflow.com/questions/7185589/how-to-calculate-expression-in-java — Rookie007, Feb 07 '14 at 08:18

score 2 · Answer 1 · answered Feb 07 '14 at 08:11

There's a lovely thing called an infix expression parser. You'll have to write your own, but if you look up how to do an infix expression parser that would be the best thing to do.

It basically looks for all things: correct syntax, and you can code it to look for mathematical validation on both sides of the equals sign.

score 0 · Accepted Answer · answered Feb 07 '14 at 10:19

I have found the solution to my problem, I am using the library written by @fas http://www.objecthunter.net/exp4j/

It is really a useful library, you can use it like this:

String left = (1000 + 700) * (50 + 25);
String right = (10000 - 5000);

Calculable calc = new ExpressionBuilder(leftCondition).build();
double result1 = calc.calculate();

calc = new ExpressionBuilder(rightCondition).build();
double result2 = calc.calculate();

System.out.println(result1 + " ------------- " + result2);

Validating mathematical operations in Java

2 Answers2