Минимально необходимый код для получения числа Пи из JavaScript в Java:
package ru.mydesignstudio.mds01; import javax.script.Invocable; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class RhinoJavaX { public void run() { ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("javascript"); String f = "function jsFunction(){" + "return Math.PI;" + "}"; try { engine.eval(f); Invocable inv = (Invocable) engine; Double pi = (Double) inv.invokeFunction("jsFunction", "John Smith"); System.out.println(pi); } catch (ScriptException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } } public static void main(String args[]) { RhinoJavaX rhino = new RhinoJavaX(); rhino.run(); } }