vaadin-framework/documentation/articles/FindingTheCurrentRootAndApplication.asciidoc

---
title: Finding The Current Root And Application
order: 9
layout: page
---

[[finding-the-current-root-and-application]]
= Finding the current root and application

There are many cases where you need a reference to the active
`Application` or `Root`, for instance for showing notifications in a click
listener. It is possible to get a reference to the component from the
event and then a reference from the component to the `Root` but Vaadin
also offers an easier way through two static methods:

[source,java]
....
Root.getCurrent()
Application.getCurrent()
....

For example when you want to show the name of the current Root class:

[source,java]
....
Button helloButton = new Button("Say Hello");
helloButton.addListener(new ClickListener() {
  public void buttonClick(ClickEvent event) {
    Notification.show("This Root is " + Root.getCurrent().getClass().getSimpleName());
  }
});
....

Similarly for `Application`, for instance to find out if the application
is running in production mode:

[source,java]
....
public void buttonClick(ClickEvent event) {
  String msg = "Running in ";
  msg += Application.getCurrent().isProductionMode() ?
    "production" : "debug";
  msg += " mode";
  Notification.show(msg);
}
....

*Note* that these are based on `ThreadLocal` so they won't work in a
background thread (or otherwise outside the standard request scope).