Not getting result when ran the Nashorn program - java-8

Question

I am new to Nashorn, I am trying to write one program and try to ran that program but i am getting the result after ran the program.Please find my code is below.
package com.nashron;
import java.io.FileNotFoundException;
import java.io.FileReader;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class InvokScriptObjectMethod {
public static void main(String[] args){
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("nashorn");
try {
engine.eval(new FileReader("src/script/Script.js"));
} catch (ScriptException | FileNotFoundException ex) {
}
}
}
JS:
var Script = Java.type("com.nashron.Script");
var var1 = new Script("who am i");
return var1.get("I am Amar");
Java :
package com.nashron;
public class Script {
public Script() {
}
public Script(String arg1) {
this.var1 = arg1;
System.out.println("this is contructor");
}
private String var1;
public String get(String arg1) {
System.out.println("this is return statement");
return this.var1 + arg1;
}
}
here I want to get the return value.
Thanks in Advance

Answer 1

A top level script cannot have "return" statements. This is as per ECMAScript specification. Your program will result in ScriptException being thrown - as there is a return statement in your JS code (at top level). If you just remove return, the last evaluated expression is returned from engine.eval call.
Example:
File: Main.java
import javax.script.*;
import java.io.*;
public class Main {
public static void main(String[] args) throws Exception {
ScriptEngineManager m = new ScriptEngineManager();
ScriptEngine e = m.getEngineByName("nashorn");
Object val = e.eval(new FileReader("x.js"));
System.out.println(val);
}
}
File: x.js
java.lang.System.getProperty("os.name");