Algebra equation parser for java

Question

I need a library to be able to parse an equation an give me the result giving the inputs.

For example something like this:

String equation = \"x + y          


        

Answer 1

You could make use of Java 1.6's scripting capabilities:

import javax.script.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
        Map vars = new HashMap();
        vars.put("x", 2);
        vars.put("y", 1);
        vars.put("z", 3);
        System.out.println("result = "+engine.eval("x + y + z", new SimpleBindings(vars)));
    }
}

which produces:

result = 6.0

For more complex expressions, JEP is a good choice.