Documentation versions (currently viewingVaadin 8)

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Client-Side Module Entry-Point

A client-side application requires an entry-point where the execution starts, much like the init() method in server-side Vaadin UIs.

Consider the following application:

package com.example.myapp.client;

import com.vaadin.ui.VButton;

public class MyEntryPoint implements EntryPoint {
    public void onModuleLoad() {
        // Create a button widget
        Button button = new Button();
        button.setText("Click me!");
        button.addClickHandler(new ClickHandler() {
            public void onClick(ClickEvent event) {
                mywidget.setText("Hello, world!");

Before compiling, the entry-point needs to be defined in a module descriptor, as described in the next section.

Module Descriptor

The entry-point of a client-side application is defined, along with any other configuration, in a client-side module descriptor, described in "Client-Side Module Descriptor". The descriptor is an XML file with suffix .gwt.xml.

<?xml version="1.0" encoding="UTF-8"?>
"-//Google Inc.//DTD Google Web Toolkit 1.7.0//EN"
    <!-- Builtin Vaadin and GWT widgets -->
    <inherits name="com.vaadin.Vaadin" />

    <!-- The entry-point for the client-side application -->
    <entry-point class="com.example.myapp.client.MyEntryPoint"/>

You might rather want to inherit the to get just the basic GWT widgets, and not the Vaadin-specific widgets and classes, most of which are unusable in pure client-side applications.

You can put static resources, such as images or CSS stylesheets, in a public folder (not a Java package) under the folder of the descriptor file. When the module is compiled, the resources are copied to the output folder. Normally in pure client-side application development, it is easier to load them in the HTML host file or in a ClientBundle (see GWT documentation), but these methods are not compatible with server-side component integration, if you use the resources for that purpose as well.