Java: Evaluate mathematical expression given in string form

Using ‘ScriptEngineManager’ class, you can evaluate a mathematical expression given in string form.

public static Object evaluateExpression(String expression) throws ScriptException {

    ScriptEngineManager mgr = new ScriptEngineManager();

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

    return engine.eval(expression);

}

App.java

package com.sample.app;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class App {

    public static Object evaluateExpression(String expression) throws ScriptException {
        ScriptEngineManager mgr = new ScriptEngineManager();
        ScriptEngine engine = mgr.getEngineByName("JavaScript");
        return engine.eval(expression);
    }

    public static void main(String args[]) throws ScriptException {
        Object value = evaluateExpression("2+3*7");

        System.out.println("2+3*7 = " + value);
        System.out.println("Result class : " + value.getClass());

        value = evaluateExpression("2+3*7.123");

        System.out.println("\n2+3*7.123 = " + value);
        System.out.println("Result class : " + value.getClass());
    }
}

Output

2+3*7 = 23

Result class : class java.lang.Integer

2+3*7.123 = 23.369

Result class : class java.lang.Double

You may like

Miscellaneous

Interview Questions

Programming Questions

Convert String to char array

Convert String to Character array

Ordered vs sorted collection

Convert byte to binary string

Convert integer to binary string