How to convert a string into a mathematical equation?

Question

I need to convert a string, such as "12 / 4", into a double value. I may not be explaining it well but I am sure you can see what I am trying to do.

I haven't tried much since I don't have much of a clue what I need to do :(.

public static double evaluateString(String str){
    double value;

    // Some code

    return value
}

If str = "12 / 4", I want the value to return 3.

https://stackoverflow.com/questions/3422673/how-to-evaluate-a-math-expression-given-in-string-form if you are asking about equations in general or is this only for division? — Joakim Danielson, May 08 '19 at 10:11
You can parse the string using a stack. Visit https://stackoverflow.com/questions/24725374/java-postfix-calculator-push-pop-method-with-a-string-array — Yunus Kerem Türk, May 08 '19 at 10:13

score 1 · Answer 1 · answered May 08 '19 at 10:13

1

I think that you could use mXparser library for Java:

You can create an Expression and evaluate it for getting result.

answered May 08 '19 at 10:13

manuelcr

score -2 · Answer 2 · answered May 08 '19 at 10:11

-2

There are Double API's valueOf which you can use it for conversion. But you have to handle the exception if its not a number(integer/double)

static Double valueOf(String s) Returns a Double object holding the double value represented by the argument string s.

answered May 08 '19 at 10:11

Shriram

And what is the result of doing `Double.valueOf("12/4")`? – Joakim Danielson May 08 '19 at 10:14
you have to use the variable one by one. mentioned that there is an api to convert from string to double. This does not mean that you have to use it directly(12/4). Thats why i mentioned there is an API. – Shriram May 08 '19 at 10:16
1

Then your answer is quite incomplete. – Joakim Danielson May 08 '19 at 10:49

2 Answers2