xref: /frameworks/base/docs/html/guide/topics/ui/accessibility/apps.jd

page.title=Making Applications Accessible
parent.title=Accessibility
parent.link=index.html
@jd:body

<div id="qv-wrapper">
<div id="qv">

  <h2>In this document</h2>
  <ol>
    <li><a href="#label-ui">Labeling User Interface Elements</a></li>
    <li><a href="#focus-nav">Enabling Focus Navigation</a>
      <ol>
        <li><a href="#focus-enable">Enabling view focus</a></li>
        <li><a href="#focus-order">Controlling focus order</a></li>
      </ol>
    </li>
    <li><a href="#custom-views">Building Accessible Custom Views</a>
      <ol>
        <li><a href="#directional-control">Handling directional controller clicks</a></li>
        <li><a href="#accessibility-methods">Implementing accessibility API methods</a></li>
        <li><a href="#send-events">Sending accessibility events</a></li>
        <li><a href="#populate-events">Populating accessibility events</a></li>
      </ol>
    </li>
    <li><a href="#test">Testing Accessibility</a>
      <ol>
        <li><a href="#test-audibles">Testing audible feedback</a></li>
        <li><a href="#test-navigation">Testing focus navigation</a></li>
      </ol>
    </li>
  </ol>

  <h2>Key classes</h2>
  <ol>
    <li>{@link android.view.accessibility.AccessibilityEvent}</li>
    <li>{@link android.view.accessibility.AccessibilityNodeInfo}</li>
    <li>{@link android.support.v4.view.accessibility.AccessibilityNodeInfoCompat}</li>
    <li>{@link android.view.View.AccessibilityDelegate}</li>
    <li>{@link android.support.v4.view.AccessibilityDelegateCompat}</li>
  </ol>

  <h2>See also</h2>
  <ol>
    <li><a href="{@docRoot}training/accessibility/index.html">Implementing Accessibility</a></li>
    <li><a href="{@docRoot}training/design-navigation/index.html">Designing Effective Navigation</a>
      </li>
    <li><a href="{@docRoot}design/index.html">Android Design</a></li>
  </ol>

</div>
</div>

<p>Applications built for Android are accessible to users with visual, physical or age-related
disabilities when they activate accessibility features and services on a device. By default,
these services make your application more accessible. However, there are further steps you should
take to optimize the accessibility of your application and ensure a pleasant experience for all your
users.</p>

<p>Making sure your application is accessible to all users is relatively easy, particularly when you
use framework-provided user interface components. If you only use these standard components for your
application, there are just a few steps required to ensure your application is accessible:</p>

<ol>
  <li>Label your {@link android.widget.ImageButton}, {@link android.widget.ImageView}, {@link
android.widget.EditText}, {@link android.widget.CheckBox} and other user interface controls using
the <a href="{@docRoot}reference/android/view/View.html#attr_android:contentDescription">
    {@code android:contentDescription}</a> attribute.</li>
  <li>Make all of your user interface elements accessible with a directional controller,
    such as a trackball or D-pad.</li>
  <li>Test your application by turning on accessibility services like TalkBack and Explore by
    Touch, and try using your application using only directional controls.</li>
</ol>

<p>Developers who create custom controls that extend from the {@link android.view.View} class have
some additional responsibilities for making sure their components are accessible for users. This
document also discusses how to make custom view controls compatible with accessibility services.</p>


<h2 id="label-ui">Labeling User Interface Elements</h2>

<p>Many user interface controls rely on visual cues to inform users of their meaning. For
example, a note-taking application might use an {@link android.widget.ImageButton} with a
picture of a plus sign to indicate that the user can add a new note. Or, an {@link
android.widget.EditText} component may have a label near it that indicates its purpose. When a user
with impaired vision accesses your application, these visual cues are often useless.</p>

<p>To provide textual information about interface controls (as an alternative to the visual cues),
use the <a href="{@docRoot}reference/android/view/View.html#attr_android:contentDescription">
{@code android:contentDescription}</a> attribute. The text you provide in this attribute is not
visible on the screen, but if a user has enabled accessibility services that provide audible
prompts, then the description in this attribute is read aloud to the user.</p>

<p>Set the <a href="{@docRoot}reference/android/view/View.html#attr_android:contentDescription">
{@code android:contentDescription}</a> attribute for every {@link android.widget.ImageButton},
{@link android.widget.ImageView}, {@link android.widget.EditText}, {@link android.widget.CheckBox}
in your application's user interface, and on any other input controls that might require additional
information for users who are not able to see it.</p>

<p>For example, the following {@link android.widget.ImageButton} sets the content description for
the plus button to the {@code add_note} string resource, which could be defined as “Add note" for an
English language interface:</p>

<pre>
&lt;ImageButton
    android:id=”@+id/add_note_button”
    android:src=”@drawable/add_note”
    android:contentDescription=”@string/add_note”/&gt;
</pre>

<p>By including the description, speech-based accessibility services can announce "Add note" when a
user moves focus to this button or hovers over it.</p>

<p class="note"><strong>Note:</strong> For {@link android.widget.EditText} fields, provide an
<a href="{@docRoot}reference/android/widget/TextView.html#attr_android:hint">android:hint</a>
attribute to help users understand what content is expected.</p>

<h2 id="focus-nav">Enabling Focus Navigation</h2>

<p>Focus navigation allows users with disabilities to step through user interface controls using a
directional controller. Directional controllers can be physical, such as a clickable trackball,
directional pad (D-pad) or arrow keys, tab key navigation with an attached keyboard or a software
application, such as the
<a href="https://play.google.com/store/apps/details?id=com.googlecode.eyesfree.inputmethod.latin">
Eyes-Free Keyboard</a>, that provides an on-screen directional control.</p>

<p>A directional controller is a primary means of navigation for many users.
Verify that all user interface (UI) controls in your application are accessible
without using the touchscreen and that clicking with the center button (or OK button) of a
directional controller has the same effect as touching the controls on the touchscreen. For
information on testing directional controls, see <a href="#test-navigation">Testing focus
navigation</a>.</p>

<h3 id="focus-enable">Enabling view focus</h3>

<p>A user interface element is accessible using directional controls when its
<a href="{@docRoot}reference/android/view/View.html#attr_android:focusable">
{@code android:focusable}</a> attribute is set to {@code true}. This setting allows users to focus
on the element using the directional controls and then interact with it. The user interface controls
provided by the Android framework are focusable by default and visually indicate focus by changing
the control’s appearance.</p>

<p>Android provides several APIs that let you control whether a user interface control is focusable
and even request that a control be given focus:</p>

<ul>
  <li>{@link android.view.View#setFocusable setFocusable()}</li>
  <li>{@link android.view.View#isFocusable isFocusable()}</li>
  <li>{@link android.view.View#requestFocus requestFocus()}</li>
</ul>

<p>When working with a view that is not focusable by default, you can make it focusable from the XML
layout file by setting the
<a href="{@docRoot}reference/android/view/View.html#attr_android:focusable">
{@code android:focusable}</a> attribute to {@code true} or by using the {@link
android.view.View#setFocusable setFocusable()} method.</p>

<h3 id="focus-order">Controlling focus order</h3>

<p>When users navigate in any direction using directional controls, focus is passed from one
user interface element (View) to another, as determined by the focus ordering. The ordering of the
focus movement is based on an algorithm that finds the nearest neighbor in a given direction. In
rare cases, the default algorithm may not match the order that you intended for your UI. In these
situations, you can provide explicit overrides to the ordering using the following XML attributes in
the layout file:</p>

<dl>
 <dt><a href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusDown"
>{@code android:nextFocusDown}</a></dt>
  <dd>Defines the next view to receive focus when the user navigates down.</dd>
 <a><a href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusLeft"
>{@code android:nextFocusLeft}</a></dt>
  <dd>Defines the next view to receive focus when the user navigates left.</dd>
 <dt><a href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusRight"
>{@code android:nextFocusRight}</a></dt>
  <dd>Defines the next view to receive focus when the user navigates right.</dd>
 <dt><a href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusUp"
>{@code android:nextFocusUp}</a></dt>
  <dd>Defines the next view to receive focus when the user navigates up.</dd>
</dl>

<p>The following example XML layout shows two focusable user interface elements where the <a
href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusDown"
>{@code android:nextFocusDown}</a> and <a
href="{@docRoot}reference/android/view/View.html#attr_android:nextFocusUp"
>{@code android:nextFocusUp}</a> attributes have been explicitly set. The {@link android.widget.TextView} is
located to the right of the {@link android.widget.EditText}. However, since these properties have
been set, the {@link android.widget.TextView} element can now be reached by pressing the down arrow
when focus is on the {@link android.widget.EditText} element: </p>

<pre>
&lt;LinearLayout android:orientation="horizontal"
        ... &gt;
    &lt;EditText android:id="@+id/edit"
        android:nextFocusDown=”@+id/text”
        ... /&gt;
    &lt;TextView android:id="@+id/text"
        android:focusable=”true”
        android:text="Hello, I am a focusable TextView"
        android:nextFocusUp=”@id/edit”
        ... /&gt;
&lt;/LinearLayout&gt;
</pre>

<p>When modifying focus order, be sure that the navigation works as expected in all directions from
each user interface control and when navigating in reverse (to get back to where you came from).</p>

<p class="note"><strong>Note:</strong> You can modify the focus order of user interface components
at runtime, using methods such as {@link android.view.View#setNextFocusDownId setNextFocusDownId()}
and {@link android.view.View#setNextFocusRightId setNextFocusRightId()}.</p>


<h2 id="custom-views">Building Accessible Custom Views</h2>

<p>If your application requires a <a href="{@docRoot}guide/topics/ui/custom-components.html">custom
view component</a>, you must do some additional work to ensure that your custom view is accessible.
These are the main tasks for ensuring the accessibility of your view:</p>

<ul>
  <li>Handle directional controller clicks</li>
  <li>Implement Accessibility API methods</li>
  <li>Send {@link android.view.accessibility.AccessibilityEvent} objects specific to your custom view</li>
  <li>Populate {@link android.view.accessibility.AccessibilityEvent} and {@link
    android.view.accessibility.AccessibilityNodeInfo} for your view</li>
</ul>


<h3 id="directional-control">Handling directional controller clicks</h3>

<p>On most devices, clicking a view using a directional controller sends a {@link
android.view.KeyEvent} with {@link android.view.KeyEvent#KEYCODE_DPAD_CENTER} to the view currently
in focus. All standard Android views already handle {@link
android.view.KeyEvent#KEYCODE_DPAD_CENTER} appropriately. When building a custom {@link
android.view.View} control, make sure this event has the same effect as touching the view on the
touchscreen. </p>

<p>Your custom control should also treat the {@link android.view.KeyEvent#KEYCODE_ENTER} event the
same as {@link android.view.KeyEvent#KEYCODE_DPAD_CENTER}. This approach makes interaction from a
full keyboard much easier for users.</p>


<h3 id="accessibility-methods">Implementing accessibility API methods</h3>

<p>Accessibility events are messages about users interaction with visual interface components in
your application. These messages are handled by <a href="services.html">Accessibility Services</a>,
which use the information in these events to produce supplemental feedback and prompts when users
have enabled accessibility services. As of Android 4.0 (API Level 14) and higher, the methods for
generating accessibility events have been expanded to provide more detailed information beyond the
{@link android.view.accessibility.AccessibilityEventSource} interface introduced in Android 1.6 (API
Level 4). The expanded accessibility methods are part of the {@link android.view.View} class as well
as the {@link android.view.View.AccessibilityDelegate} class. The methods are as follows:</p>

<dl>
 <dt>{@link android.view.View#sendAccessibilityEvent sendAccessibilityEvent()}</dt>
  <dd>(API Level 4) This method is called when a user takes action on a view. The event is
classified with a user action type such as {@link
android.view.accessibility.AccessibilityEvent#TYPE_VIEW_CLICKED TYPE_VIEW_CLICKED}. You typically do
not need to implement this method unless you are creating a custom view.</dd>

  <dt>{@link android.view.View#sendAccessibilityEventUnchecked
sendAccessibilityEventUnchecked()}</dt>
  <dd>(API Level 4) This method is used when the calling code needs to directly control the check
for accessibility being enabled on the device ({@link
android.view.accessibility.AccessibilityManager#isEnabled AccessibilityManager.isEnabled()}). If
you do implement this method, you must assume that the calling method has already checked that
accessibility is enabled and the result is {@code true}. You typically do not need to implement this
method for a custom view.</dd>

  <dt>{@link android.view.View#dispatchPopulateAccessibilityEvent
dispatchPopulateAccessibilityEvent()} </dt>
  <dd>(API Level 4) The system calls this method when your custom view generates an
accessibility event. As of API Level 14, the default implementation of this method calls {@link
android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()} for this view and
then the {@link android.view.View#dispatchPopulateAccessibilityEvent
dispatchPopulateAccessibilityEvent()} method for each child of this view. In order to support
accessibility services on revisions of Android <em>prior</em> to 4.0 (API Level 14) you
<em>must</em> override this method and populate {@link
android.view.accessibility.AccessibilityEvent#getText} with descriptive text for your custom
view.</dd>

  <dt>{@link android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()}</dt>
  <dd>(API Level 14) This method sets the text output of an {@link
android.view.accessibility.AccessibilityEvent} for your view. This method is also called if the
view is a child of a view which generates an accessibility event.

  <p class="note"><strong>Note:</strong> Modifying additional attributes beyond the text within
this method potentially overwrites properties set by other methods. So, while you are able modify
attributes of the accessibility event with this method, you should limit these changes
to text content only and use the {@link android.view.View#onInitializeAccessibilityEvent
onInitializeAccessibilityEvent()} method to modify other properties of the event.</p>

  <p class="note"><strong>Note:</strong> If your implementation of this event calls for completely
overiding the output text without allowing other parts of your layout to modify its content, then
do not call the super implementation of this method in your code.</p>
  </dd>

  <dt>{@link android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()}</dt>
  <dd>(API Level 14) The system calls this method to obtain additional information about the
state of the view, beyond text content. If your custom view provides interactive control beyond a
simple {@link android.widget.TextView} or {@link android.widget.Button}, you should override this
method and set the additional information about your view into the event using this method, such as
password field type, checkbox type or states that provide user interaction or feedback. If you
do override this method, you must call its super implementation and then only modify properties
that have not been set by the super class.</dd>

  <dt>{@link android.view.View#onInitializeAccessibilityNodeInfo
onInitializeAccessibilityNodeInfo()}</dt>
  <dd>(API Level 14) This method provides accessibility services with information about the state of
the view. The default {@link android.view.View} implementation sets a standard set of view
properties, but if your custom view provides interactive control beyond a simple {@link
android.widget.TextView} or {@link android.widget.Button}, you should override this method and set
the additional information about your view into the {@link
android.view.accessibility.AccessibilityNodeInfo} object handled by this method.</dd>

  <dt>{@link android.view.ViewGroup#onRequestSendAccessibilityEvent
onRequestSendAccessibilityEvent()}</dt>
  <dd>(API Level 14) The system calls this method when a child of your view has generated an
{@link android.view.accessibility.AccessibilityEvent}. This step allows the the parent view to amend
the accessibility event with additional information. You should implement this method only if your
custom view can have child views and if the parent view can provide context information to the
accessibility event that would be useful to accessibility services.</dd>
</dl>

<p>In order to support these accessibility methods for a custom view, you should take one of the
following approaches:</p>

<ul>
  <li>If your application targets Android 4.0 (API level 14) and higher, override and implement the
accessibility methods listed above directly in your custom view class.</li>
  <li>If your custom view is intended to be compatible with Android 1.6 (API Level 4) and above, add
the Android <a href="{@docRoot}sdk/compatibility-library.html">Support Library</a>, revision 5 or
higher, to your project. Then, within your custom view class, call the
{@link android.support.v4.view.ViewCompat#setAccessibilityDelegate
ViewCompat.setAccessibilityDelegate()} method to implement the accessibility methods
above. For an example of this approach, see the Android Support Library (revision 5 or higher)
sample {@code AccessibilityDelegateSupportActivity} in 
({@code &lt;sdk&gt;/extras/android/support/v4/samples/Support4Demos/})
  </li>
</ul>

<p>In either case, you should implement the following accessibility methods for your custom view
class:</p>

<ul>
  <li>{@link android.view.View#dispatchPopulateAccessibilityEvent
    dispatchPopulateAccessibilityEvent()}</li>
  <li>{@link android.view.View#onPopulateAccessibilityEvent
    onPopulateAccessibilityEvent()}</li>
  <li>{@link android.view.View#onInitializeAccessibilityEvent
    onInitializeAccessibilityEvent()}</li>
  <li>{@link android.view.View#onInitializeAccessibilityNodeInfo
    onInitializeAccessibilityNodeInfo()}</li>
</ul>

<p>For more information about implementing these methods, see <a href="#populate-events">Populating
Accessibility Events</a>.</p>


<h3 id="send-events">Sending accessibility events</h3>

<p>Depending on the specifics of your custom view, it may need to send {@link
android.view.accessibility.AccessibilityEvent} objects at a different times or for events not
handled by the default implementation. The {@link android.view.View} class provides a default
implementation for these event types:</p>

<ul>
  <li>Starting with API Level 4:
    <ul>
      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_CLICKED}</li>

      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_LONG_CLICKED}</li>

      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_FOCUSED}</li>
    </ul>
  </li>
  <li>Starting with API Level 14:
    <ul>
      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_SCROLLED}</li>

      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_HOVER_ENTER}</li>

      <li>{@link android.view.accessibility.AccessibilityEvent#TYPE_VIEW_HOVER_EXIT}</li>
    </ul>
  </li>
</ul>

<p class="note"><strong>Note:</strong> Hover events are associated with the Explore by
Touch feature, which uses these events as triggers for providing audible prompts for user interface
elements.</p>

<p>In general, you should send an {@link android.view.accessibility.AccessibilityEvent} whenever the
content of your custom view changes. For example, if you are implementing a custom slider bar that
allows a user to select a numeric value by pressing the left or right arrows, your custom view
should emit an event of type {@link
android.view.accessibility.AccessibilityEvent#TYPE_VIEW_TEXT_CHANGED} whenever the slider
value changes. The following sample code demonstrates the use of the {@link
android.view.accessibility.AccessibilityEventSource#sendAccessibilityEvent
sendAccessibilityEvent()} method to report this event.</p>

<pre>
&#64;Override
public boolean onKeyUp (int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
        mCurrentValue--;
        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED);
        return true;
    }
    ...
}
</pre>


<h3 id="populate-events">Populating accessibility events</h3>

<p>Each {@link android.view.accessibility.AccessibilityEvent} has a set of required properties that
describe the current state of the view. These properties include things such as the view’s class
name, content description and checked state. The specific properties required for each event type
are described in the {@link android.view.accessibility.AccessibilityEvent} reference documentation.
The {@link android.view.View} implementation provides default values for these properties. Many of
these values, including the class name and event timestamp, are provided automatically. If you are
creating a custom view component, you must provide some information about the content and
characteristics of the view. This information may be as simple as a button label, but may also
include additional state information that you want to add to the event.</p>

<p>The minimum requirement for providing information to accessibility services with a custom
view is to implement {@link android.view.View#dispatchPopulateAccessibilityEvent
dispatchPopulateAccessibilityEvent()}. This method is called by the system to request
information for an {@link android.view.accessibility.AccessibilityEvent} and makes your custom
view compatible with accessibility services on Android 1.6 (API Level 4) and higher. The
following example code demonstrates a basic implementation of this method.</p>

<pre>
&#64;Override
public void dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
    super.dispatchPopulateAccessibilityEvent(event);
    // Call the super implementation to populate its text to the event, which
    // calls onPopulateAccessibilityEvent() on API Level 14 and up.

    // In case this is running on a API revision earlier that 14, check
    // the text content of the event and add an appropriate text
    // description for this custom view:
    CharSequence text = getText();
    if (!TextUtils.isEmpty(text)) {
        event.getText().add(text);
    }
}
</pre>

<p>On Android 4.0 (API Level 14) and higher, the {@link
android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()} and
{@link android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()}
methods are the recommended way to populate or modify the information in an {@link
android.view.accessibility.AccessibilityEvent}. Use the 
{@link android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()} method
specifically for adding or modifying the text content of the event, which is turned into audible
prompts by accessibility services such as TalkBack. Use the
{@link android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()} method for
populating additional information about the event, such as the selection state of the view.</p>

<p>In addition, you should also implement the
{@link android.view.View#onInitializeAccessibilityNodeInfo onInitializeAccessibilityNodeInfo()}
method. {@link android.view.accessibility.AccessibilityNodeInfo} objects populated by this method
are used by accessibility services to investigate the view hierarchy that generated an accessibility
event after receiving that event, to obtain a more detailed context information and provide
appropriate feedback to users.</p>

<p>The example code below shows how override these three methods by using
{@link android.support.v4.view.ViewCompat#setAccessibilityDelegate
ViewCompat.setAccessibilityDelegate()}. Note that this sample code requires that the Android
<a href="{@docRoot}sdk/compatibility-library.html">Support Library</a> for API Level 4 (revision 5
or higher) is added to your project.</p>

<pre>
ViewCompat.setAccessibilityDelegate(new AccessibilityDelegateCompat() {
    &#64;Override
    public void onPopulateAccessibilityEvent(View host, AccessibilityEvent event) {
        super.onPopulateAccessibilityEvent(host, event);
        // We call the super implementation to populate its text for the
        // event. Then we add our text not present in a super class.
        // Very often you only need to add the text for the custom view.
        CharSequence text = getText();
        if (!TextUtils.isEmpty(text)) {
            event.getText().add(text);
        }
    }
    &#64;Override
    public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(host, event);
        // We call the super implementation to let super classes
        // set appropriate event properties. Then we add the new property
        // (checked) which is not supported by a super class.
        event.setChecked(isChecked());
    }
    &#64;Override
    public void onInitializeAccessibilityNodeInfo(View host,
            AccessibilityNodeInfoCompat info) {
        super.onInitializeAccessibilityNodeInfo(host, info);
        // We call the super implementation to let super classes set
        // appropriate info properties. Then we add our properties
        // (checkable and checked) which are not supported by a super class.
        info.setCheckable(true);
        info.setChecked(isChecked());
        // Quite often you only need to add the text for the custom view.
        CharSequence text = getText();
        if (!TextUtils.isEmpty(text)) {
            info.setText(text);
        }
    }
}
</pre>

<p>On applications targeting Android 4.0 (API Level 14) and higher, these methods can be implemented
directly in your custom view class. For another example of this approach, see the Android
<a href="{@docRoot}sdk/compatibility-library.html">Support Library</a> (revision 5 or higher) sample
{@code AccessibilityDelegateSupportActivity} in 
({@code &lt;sdk&gt;/extras/android/support/v4/samples/Support4Demos/}).</p>

<p class="note"><strong>Note:</strong> You may find information on implementing accessibility for
custom views written prior to Android 4.0 that describes the use of the
{@link android.view.View#dispatchPopulateAccessibilityEvent dispatchPopulateAccessibilityEvent()}
method for populating AccessibilityEvents. As of the Android 4.0 release, however, the recommended
approach is to use the
{@link android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()} and
{@link android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()}
methods.</p>


<h2 id="test">Testing Accessibility</h2>

<p>Testing the accessibility of your application is an important part of ensuring your users have a
great experience. You can test the most important parts of accessibility by testing your application
with audible feedback enabled and testing navigation within your application using directional
controls.</p>

<h3 id="test-audibles">Testing audible feedback</h3>
<p>You can simulate the experience for many users by enabling an accessibility service that speaks
as you move around the screen. The Explore by Touch accessibility service, which is available on
devices with Android 4.0 and later. The <a
href="https://play.google.com/store/apps/details?id=com.google.android.marvin.talkback">TalkBack</a>
accessibility service, by the <a href="http://code.google.com/p/eyes-free/">Eyes-Free
Project</a> comes preinstalled on many Android devices.</p>

<p>To enable TalkBack on revisions of Android prior to Android 4.0:</p>
<ol>
  <li>Launch the Settings application.</li>
  <li>Navigate to the <strong>Accessibility</strong> category and select it.</li>
  <li>Select <strong>Accessibility</strong> to enable it.</li>
  <li>Select <strong>TalkBack</strong> to enable it.</li>
</ol>

<p class="note"><strong>Note:</strong> If the TalkBack accessibility service is not available, you
can install it for free from <a href="http://play.google.com">Google Play</a>.</p>

<p>To enable Explore by Touch on Android 4.0 and later:</p>
<ol>
  <li>Launch the Settings application.</li>
  <li>Navigate to the <strong>Accessibility</strong> category and select it.</li>
  <li>Select the <strong>TalkBack</strong> to enable it.</li>
  <li>Return to the <strong>Accessibility</strong> category and select <strong>Explore by
Touch</strong> to enable it.
    <p class="note"><strong>Note:</strong> You must turn on TalkBack <em>first</em>, otherwise this
option is not available.</p>
  </li>
</ol>

<h3 id="test-navigation">Testing focus navigation</h3>

<p>As part of your accessibility testing, you can test navigation of your application using focus,
even if your test devices does not have a directional controller. The <a
href="{@docRoot}guide/developing/tools/emulator.html">Android Emulator</a> provides a
simulated directional controller that you can easily use to test navigation. You can also use a
software-based directional controller, such as the one provided by the
<a href="https://play.google.com/store/apps/details?id=com.googlecode.eyesfree.inputmethod.latin">
Eyes-Free Keyboard</a> to simulate use of a D-pad.</p>