vaadin-framework/documentation/components/components-button.asciidoc

---
title: Button
order: 14
layout: page
---

[[components.button]]
= [classname]#Button#

ifdef::web[]
[.sampler]
image:{live-demo-image}[alt="Live Demo", link="http://demo.vaadin.com/sampler/#ui/interaction/button"]
endif::web[]


The [classname]#Button# component is normally used for initiating some action,
such as finalizing input in forms. When the user clicks a button, a
[classname]#Button.ClickEvent# is fired, which can be handled by adding a __click listener__
using either the [methodname]#onClick()# or the [methodname]#addClickListener()# method.

[[figure.component.button.basic]]
.A [classname]#Button#
image::img/button-example1.png[width=35%, scaledwidth=60%]

You can handle button clicks most easily with an anonymous class or a lambda expression, as follows:

[source, java]
----
Button button = new Button("Do not press this button");

button.addClickListener(clickEvent ->
    Notification.show("Do not press this button again"));
----
See the http://demo.vaadin.com/book-examples-vaadin7/book#component.button.basic[on-line example, window="_blank"].

The listener can also be given in the constructor, which is often perhaps simpler.

////
If you handle several buttons in the same listener, you can differentiate
between them either by comparing the [classname]#Button# object reference
returned by the [methodname]#getButton()# method of
[classname]#Button.ClickEvent# to a kept reference. For a detailed description
of these patterns together with some examples, please see
<<dummy/../../../framework/architecture/architecture-events#architecture.events,"Events and Listeners">>.
////

== CSS Style Rules


[source, css]
----
.v-button { }
  .v-button-wrap { }
    .v-button-caption { }
----

A button has an overall [literal]#++v-button++# style. The caption has
[literal]#++v-button-caption++# style. There is also an intermediate wrap
element, which may help in styling in some cases.

The button component has many style variants in the Valo theme, as illustrated in <<figure.component.button.basic>>.
The styles are defined in the [classname]#ValoTheme# class.

[[figure.component.button.basic]]
.Button in different styles of the Valo theme
image::img/button-valo-styles.png[width=70%, scaledwidth=100%]