Pass value and get return value from script : ScriptEngines « Development « Java Tutorial

1. Java Tutorial
2. Development
3. ScriptEngines

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

public class MonthlyPayment {
  public static void main(String[] args) throws Exception {
    ScriptEngineManager manager = new ScriptEngineManager();
    ScriptEngine engine = manager.getEngineByExtension("js");
    String calcMonthlyPaymentScript = "intrate = intrate/1200.0;"
        + "payment = principal*intrate*(Math.pow (1+intrate, months)/"
        + "                            (Math.pow (1+intrate,months)-1));";

    engine.put("principal", 20000.0);
    System.out.println("Principal = " + engine.get("principal"));
    engine.put("intrate", 6.0);
    System.out.println("Interest Rate = " + engine.get("intrate") + "%");
    engine.put("months", 360);
    System.out.println("Months = " + engine.get("months"));
    engine.eval(calcMonthlyPaymentScript);
    System.out.printf("Monthly Payment = %.2f\n", engine.get("payment"));
  }
}