How to calculate a value from a user input? (Java)

Question

I'm trying to write a program that will take an input from a user and calculate the total from their input. For example, if the user input "5+30*2" the output would be "65". I've spent hours on this so far and can't seem to get a correct solution. Does anyone have any idea how i would do this?

i found this question for you http://stackoverflow.com/questions/3422673/evaluating-a-math-expression-given-in-string-form — Marco Acierno, Apr 21 '14 at 16:08
Where exactly are you stuck? You are having problems with getting the inputs, parsing the equation or displaying the output? — Kashif Nazar, Apr 21 '14 at 16:17
[Edsger Dijkstra's Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm) — David Conrad, Apr 21 '14 at 16:27
possible duplicate of [Equation (expression) parser with precedence?](http://stackoverflow.com/questions/28256/equation-expression-parser-with-precedence) — Zoyd, Apr 21 '14 at 16:33

score 0 · Accepted Answer · answered Apr 21 '14 at 16:52

With JDK1.6, you can use the built-in Javascript engine.

this is tested and working .

import java.io.*;
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import java.util.Scanner;
import javax.script.ScriptException;

public class MathExpress {


    public static void main(String[] args) throws ScriptException {
        Scanner console = new Scanner(System.in);

        System.out.println("Enter your arithematic oparation ");
        String Mathex= console.nextLine();

        ScriptEngineManager mgr = new ScriptEngineManager();
        ScriptEngine engine = mgr.getEngineByName("JavaScript");

        System.out.println(engine.eval(Mathex));




    }
}

How to calculate a value from a user input? (Java)

1 Answers1