http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-May/004572.html

import javax.script.*;
import jdk.nashorn.api.scripting.*;

public class Main {
    ScriptEngineFactory factory = new NashornScriptEngineFactory();
    ScriptEngine engine = factory.getScriptEngine();
    Bindings globalBindings = new SimpleBindings();
    Bindings engineBindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);
    ScriptContext context = new SimpleScriptContext();

    public static void main(String[] ar) throws Exception {
        Main main = new Main();
        main.context.setBindings(main.globalBindings, ScriptContext.GLOBAL_SCOPE);
        main.context.setBindings(main.engineBindings, ScriptContext.ENGINE_SCOPE);

        main.engineBindings.put("program", main);
        main.globalBindings.put("text", "initial text");

        main.engine.eval(
            " print(text); " +
            " program.someMethod(); " +
            " print(text);", main.context);

        /* Expected output:
           initial text
           another text
           initial text

           Output seen:
           initial text
           another text
           another text
        */
    }

    public void someMethod() throws Exception {
        // a context with a new global bindings, same engine bindings
        ScriptContext context = new SimpleScriptContext();
        Bindings globalBindings = new SimpleBindings();
        context.setBindings(globalBindings, ScriptContext.GLOBAL_SCOPE);
        context.setBindings(engineBindings, ScriptContext.ENGINE_SCOPE);

        globalBindings.put("text", "another text");
        engine.eval("print(text)", context);
    }
}