Java JSObject.eval() is not working, is there any import needed?

Question

I have tried a few different ways to JavaScript functions, control structures, etc, in java, among them, JSObject.eval():

public class Interpreter{
    public static void eval (String input) {
        JSObject.eval(input);
    }
    public static void main (String[ ] args) {
        Interpreter Program = new Interpreter();
        Program.eval("console.log('hello');");
    }
}

Outputs:

_Interpreter.java:92: error: cannot find symbol
        JSObject.eval(input);
        ^
  symbol:   variable JSObject
  location: class Interpreter
1 error_

Answer 1

You can use the ScriptEngine API to evaluate JS scripts:

//with the following imports:
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;


public static void main (String[ ] args) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("js");
        try {
            Object result = engine.eval("var a = 4, b = 5; a * b");
            System.out.println(result);
        }catch (ScriptException e){
            e.printStackTrace();
        }
    }