Untitled

How to do mathematical calculation in java based on user input string? [closed]
String EXPRESION = null;
        EXPRESION = JOptionPane.showInputDialog("Please enter expresion for dy/dx");
        double x = 1.4;
        double y = 5;
        double output = HERE IS THE PROBLEM
        JOptionPane.showMessageDialog("The value is" +output);

import jscheme.JS;

String query = "(+ 10 20)";
System.out.println(query + " = " + JS.eval(query));

import bsh.*;

 class Operation
 {

    public static void main(String[] args)throws Exception
    {
        Interpreter i=new Interpreter();
        int r=(Integer)i.eval(args[0]);
        System.out.println(r);
    }
}