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Java Program to parse a mathematical expression and operators
At first, we have set the mathematical expressions:
String one = "10+15*20-5/5"; String two = "3+5-6"; String three = "9+2*(6-3+7)";
To parse mathematical expression, use Nashorn JavaScript in Java i.e. scripting. Nashorn invoke dynamics feature, introduced in Java 7 to improve performance.
For scripting, use the ScriptEngineManager class for the engine:
ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("Nashorn");Now for JavaScript code from string, use eval i.e. execute the script. Here, we are parsing mathematical expressions set above:
Object expResult1 = scriptEngine.eval(one); Object expResult2 = scriptEngine.eval(two); Object expResult3 = scriptEngine.eval(three);
Example
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class Demo {
public static void main(String[] args) throws Exception {
String one = "10+15*20-5/5";
String two = "3+5-6";
String three = "9+2*(6-3+7)";
String four = "(10 % 3)*2+6";
String five = "3*3+3";
ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("Nashorn");
Object expResult1 = scriptEngine.eval(one);
Object expResult2 = scriptEngine.eval(two);
Object expResult3 = scriptEngine.eval(three);
Object expResult4 = scriptEngine.eval(four);
Object expResult5 = scriptEngine.eval(five);
System.out.println("Result of expression1 = " + expResult1);
System.out.println("Result of expression2 = " + expResult2);
System.out.println("Result of expression3 = " + expResult3);
System.out.println("Result of expression4 = " + expResult4);
System.out.println("Result of expression5 = " + expResult5);
}
}Output
Result of expression1 = 309 Result of expression2 = 2 Result of expression3 = 29 Result of expression4 = 8 Result of expression5 = 12
Updated on: 30-Jul-2019
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