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Optimize your app for autofill

Apps that use standard views work with the autofill framework without requiring special configuration. However, you can optimize how your app works with the framework. For a guided tutorial, see the Optimize your app for autofill codelab.

Set up the autofill environment

This section describes how to set up basic autofill functionality for your app.

Configure an autofill service

An autofill service must be configured on your device for your app to use the autofill framework. Although most phones and tablets running Android 8.0 (API level 26) and higher ship with an autofill service, we recommend that you use a test service when testing your app, such as the autofill service in the Android autofill framework sample. When using an emulator, you must explicitly set an autofill service because the emulator may not come with a default service.

After you have installed the test autofill service from the sample app, enable the autofill service by navigating to Settings > System > Languages & input > Advanced > Input assistance > Autofill service.

For more information about configuring an emulator for testing autofill, see Test your app with autofill.

Provide hints for autofill

The autofill service attempts to determine the type of each view using heuristics. However, if your app relies on these heuristics, autofill behavior may unexpectedly change as you update your app. To ensure that the autofill service correctly identifies your app's form factors, you should provide autofill hints.

You can set these hints using the android:autofillHints attribute:

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:autofillHints="password" />

You may also set them using the setAutofillHints() method:

TextView password = findViewById(R.id.password);
password.setAutofillHints(View.AUTOFILL_HINT_PASSWORD);

The autofill framework doesn't validate the hints; they are just passed along without change or validation to the autofill service. Although they can have any value, it's recommended that you use predefined hint constants, such as AUTOFILL_HINT_USERNAME for a username or AUTOFILL_HINT_CREDIT_CARD_NUMBER for a credit card number.

Mark fields as important for autofill

You can tell the system whether the individual fields in your app should be included in a view structure for autofill purposes. By default, the view uses the IMPORTANT_FOR_AUTOFILL_AUTO mode, which lets Android use its heuristics to determine if the view is important for autofill.

You can set the importance using the android:importantForAutofill attribute:

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:importantForAutofill="no" />

The value of importantForAutofill may be any of the values defined in android:importantForAutofill:

auto
Let the Android System use its heuristics to determine if the view is important for autofill.
no
This view isn't important for autofill.
noExcludeDescendants
This view and its children aren't important for autofill.
yes
This view is important for autofill.
yesExcludeDescendants
This view is important for autofill, but its children aren't important for autofill.

You can also use the setImportantForAutofill() method:

TextView captcha = findViewById(R.id.captcha);
captcha.setImportantForAutofill(View.IMPORTANT_FOR_AUTOFILL_NO);

There are cases when a view, a view structure, or the whole activity isn't important for autofill:

  • A CAPTCHA field in a login activity usually isn't important for autofill. In cases like this, you can mark the view as IMPORTANT_FOR_AUTOFILL_NO.
  • In a view where the user creates content, such as a text or spreadsheet editor, the whole view structure is usually not important for autofill. In cases like this, you can mark the view as IMPORTANT_FOR_AUTOFILL_NO_EXCLUDE_DESCENDANTS to make sure that all the children are also marked as not important for autofill.
  • In some activities within games, such as those that display gameplay, none of the views in the activities are important for autofill. You can mark the root view as IMPORTANT_FOR_AUTOFILL_NO_EXCLUDE_DESCENDANTS to ensure that all the views in the activity are marked as not important for autofill.

Associate website and mobile app data

Autofill services such as Autofill with Google can share user login data among browsers and Android devices after the app and a website are associated. When a user chooses the same autofill service on both platforms, signing in to your web app makes their login credentials available to autofill when they sign in to your corresponding Android app.

To associate your Android app with your website, you must host a Digital Asset Link with the delegate_permission/common.get_login_creds relation in your site. Then, declare the association in your app's AndroidManifest.xml file. For detailed instructions about how to associate your website with your Android app, see Enable automatic sign-in across apps and websites.

Complete an autofill workflow

This section describes specific scenarios in which you can take steps to improve autofill functionality for users of your app.

Determine whether autofill is enabled

You can implement additional autofill functionality in your app, or even in particular views of your app, if autofill is available to the user. For example, TextView shows an autofill entry in the overflow menu if autofill is enabled for the user. To check whether autofill is enabled for the user, call the isEnabled() method of the AutofillManager object.

Users can enable or disable autofill as well as change the autofill service by navigating to Settings > System > Languages & input > Advanced > Input assistance > Autofill service. Your app cannot override the user's autofill settings.

To ensure your sign up and login experience is optimized for users without autofill, consider implementing Smart Lock for Passwords.

Force an autofill request

Sometimes, you may need to force an autofill request to occur in response to a user action. For example, TextView offers an autofill menu item when the user long-presses the view. The following code example shows how to force an autofill request:

public void eventHandler(View view) {
    AutofillManager afm = context.getSystemService(AutofillManager.class);
    if (afm != null) {
        afm.requestAutofill();
    }
}

You can also use the cancel() method to cancel the current autofill context. This can be useful, for example, if you have a button that clears the fields on a login page.

Use the correct autofill type for data in picker controls

Pickers are useful in some autofill scenarios by providing a UI that lets users change the value of a field that stores date or time data. For example, in a credit card form, a date picker lets users enter or change the expiration date of their credit card. However, you must use another view, such as an EditText, to display the data when the picker isn't visible.

An EditText object natively expects autofill data of type AUTOFILL_TYPE_TEXT. If you are using a different type of data, you should create a custom view that inherits from EditText and implements the methods required to handle the corresponding type of data. For instance, if you have a date field, implement the methods with logic that correctly handles values of type AUTOFILL_TYPE_DATE.

When you specify the autofill data type, the autofill service is able to create an appropriate representation of the data displayed in the view. For more information, see Using pickers with autofill.

Finish the autofill context

The autofill framework saves user input for future use by showing a "Save for autofill?" dialog after the autofill context is finished. Typically, the autofill context is finished when an activity finishes. However, there are some situations where you need to explicitly notify the framework; for example, if you're using the same activity but different fragments for both your login and content screens. In these special situations, you can explicitly finish the context by calling AutofillManager.commit().

Support for custom views

Custom views can specify the metadata that is exposed to the autofill framework by using the autofill API. Some views act as a container of virtual children, such as views that contain OpenGL-rendered UI. These views must use the API to specify the structure of the information used in the app before they can work with the autofill framework.

If your app uses custom views, you must consider the following scenarios:

  • The custom view provides a standard view structure, or a default view structure.
  • The custom view has a virtual structure, or a view structure that isn't available to the autofill framework.

Custom views with standard view structure

Custom views can define the metadata that autofill requires to work. You should make sure that your custom view manages the metadata appropriately to work with the autofill framework. Your custom view should take the following actions:

  • Handle the autofill value that the framework sends to your app.
  • Provide the autofill type and value to the framework.

When autofill is triggered, the autofill framework calls autofill() on your view and sends the value that your view should use. You should implement autofill() to specify how your custom view handles the autofill value.

Your view should specify an autofill type and value by overriding the getAutofillType() and getAutofillValue() methods, respectively. By adding this code, you ensure that your view can provide appropriate autofill types and values to the framework.

Finally, autofill shouldn't fill the view if the user can't provide a value for the view in its current state (for example, if the view is disabled). In these cases, getAutofillType() should return AUTOFILL_TYPE_NONE, getAutofillValue() should return null, and autofill() should do nothing.

The following cases require additional steps to properly work within the framework:

  • The custom view is editable.
  • The custom view contains sensitive data.

The custom view is editable

If the view is editable, you should notify the autofill framework about changes by calling notifyValueChanged() on the AutofillManager object.

The custom view contains sensitive data

If the view contains personally identifiable information (PII)—such as email addresses, credit card numbers, and passwords—it should be marked as such. In general, views whose content come from static resources don't contain sensitive data, but views whose content is dynamically set can contain sensitive data. For example, a label that contains type your username doesn't contain sensitive data, while a label that contains Hello, John does. To mark whether the view contains sensitive data or not, implement onProvideAutofillStructure() and call setDataIsSensitive() on the ViewStructure object.

The following code example shows how to mark the data in the view structure as sensitive or not:

@Override
public void onProvideAutofillStructure(ViewStructure structure, int flags) {
    super.onProvideAutofillStructure(structure, flags);

    // Content that comes from static resources generally isn't sensitive.
    boolean sensitive = !contentIsSetFromResources();
    structure.setDataIsSensitive(sensitive);
}

If the view accepts only predefined values, you can use the setAutofillOptions() method to set the options that can be used to autofill this view. In particular, views whose autofill type is AUTOFILL_TYPE_LIST should use this method because the autofill service can do a better job if it knows the options that are available to fill the view.

Views that use an adapter, such as a Spinner, are a similar case. For example, a spinner that provides dynamically-created years (based on the current year) to use in credit card expiration fields can implement the getAutofillOptions() method of the Adapter interface to provide a list of years.

Views that use an ArrayAdapter also can provide lists of values. ArrayAdapter automatically sets autofill options for static resources. If you provide the values dynamically, however, you should override getAutofillOptions().

Custom views with virtual structure

The autofill framework requires a view structure before it can edit and save the information in your app's UI. There are some situations where the view structure isn't available to the framework:

  • The app uses a low-level rendering engine, such as OpenGL, to render the UI.
  • The app uses an instance of Canvas to draw the UI.

In these cases, you can specify a view structure by implementing onProvideAutofillVirtualStructure() and following these steps:

  1. Increase the child count of the view structure by calling addChildCount().
  2. Add a child by calling newChild().
  3. Set the autofill ID for the child by calling setAutofillId().
  4. Set relevant properties, such as the autofill value and type.
  5. If the data in the virtual child is sensitive, you should pass true to setDataIsSensitive() or false otherwise.

The following code snippet shows how to create a new child in the virtual structure:

@Override
public void onProvideAutofillVirtualStructure(ViewStructure structure,
                                              int flags) {
    super.onProvideAutofillVirtualStructure(structure, flags);

    // Create a new child in the virtual structure.
    structure.addChildCount(1);
    ViewStructure child =
        structure.newChild(childIndex);

    // Set the autofill ID for the child.
    child.setAutofillId(structure.getAutofillId(), childVirtualId);

    // Populate the child by providing properties such as value and type.
    child.setAutofillValue(childAutofillValue);
    child.setAutoFillType(childAutofillType);

    // Some children can provide a list of values. For example, if the child is
    // a spinner.
    CharSequence childAutofillOptions[] = { "option1", "option2" };
    child.setAutofillOptions(childAutofillOptions);

    // Just like other types of views, mark the data as sensitive, if
    // appropriate.
    boolean sensitive = !contentIsSetFromResources();
    child.setDataIsSensitive(sensitive);
}

When elements in a virtual structure change, you should notify the framework by performing the following tasks:

  • If the focus inside the children changes, call notifyViewEntered() and notifyViewExited() on the AutofillManager object.
  • If the value of a child changes, call notifyValueChanged() on the AutofillManager object.
  • If the view hierarchy is no longer available because the user has completed a step in the workflow (for example, the user signed in using a login form) call commit() on the AutofillManager object.
  • If the view hierarchy isn't valid anymore because the user has canceled a step in the workflow (for example, if the user clicks a button that clears a login form), call cancel() on the AutofillManager object.

Use callbacks on autofill events

If your app provides its own autocomplete views, you need a mechanism that tells the app to enable or disable the views in response to changes in the UI autofill affordance. The autofill framework provides this mechanism in the form of AutofillCallback.

This class provides the onAutofillEvent(View, int) method, which the app calls after a change in the autofill state associated with a view. There is also an overloaded version of this method, which includes a childId parameter that your app can use with virtual views. The available states are defined as constants in the callback.

You can register a callback using the registerCallback() method of the AutofillManager class. The following code example shows how to declare a callback for autofill events:

AutofillManager afm = this.getSystemService(AutofillManager.class);

afm.registerCallback(new AutofillManager.AutofillCallback() {
    // For virtual structures, override
    // onAutofillEvent(View view, int childId, int event) instead.
    @Override
    public void onAutofillEvent(View view, int event) {
        super.onAutofillEvent(view, event);
        switch (event) {
            case EVENT_INPUT_HIDDEN:
                // The autofill affordance associated with the view was hidden.
                break;
            case EVENT_INPUT_SHOWN:
                // The autofill affordance associated with the view was shown.
                break;
            case EVENT_INPUT_UNAVAILABLE:
                // Autofill isn't available.
                break;
        }
    }
});

When it's time to remove the callback, use the unregisterCallback() method.

Customize the autofill highlighted drawable

When a view is autofilled, the platform renders a Drawable over the view to indicate the view contents have been autofilled. By default, this drawable is a solid rectangle with a translucent color that is slightly darker than the theme's color used to draw backgrounds. The drawable doesn't need to be changed, but it can be customized by overriding the android:autofilledHighlight item of the theme used by the application or activity, as shown in this example:

res/values/styles.xml

<resources>
    <style name="MyAutofilledHighlight" parent="...">
        <item name="android:autofilledHighlight">@drawable/my_drawable</item>
    </style>
</resources>

res/drawable/my_drawable.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#4DFF0000" />
</shape>

AndroidManifest.xml

<application ...
    android:theme="@style/MyAutofilledHighlight">
<!-- or -->
<activity ...
    android:theme="@style/MyAutofilledHighlight">

Authenticate for autofill

An autofill service can require the user to authenticate before the service can complete fields in your app. You don't need to update your app because this authentication happens within the service.

Assign autofill IDs to recycled views

Containers that recycle views, such as the RecyclerView class, are very useful for apps that need to display scrolling lists of elements based on large data sets. As the container scrolls, the system reuses views in the layout, but the views then contain new content. If the initial contents of the view are filled out, the autofill service retains the logical meaning of the views using their autofill IDs. A problem arises when, as the system reuses the views in the layout, the views' logical IDs remain the same, causing the wrong autofill user data to be associated with an autofill ID.

To solve this problem on devices running Android 9 (API level 28) and higher, you can explicitly manage the autofill ID of views that are used by RecyclerView using these new methods:

  • The getNextAutofillId() method gets a new autofill ID that is unique to the activity.
  • The setAutofillId() method sets the unique, logical autofill ID of this view in the activity.

Address known issues

This section presents workarounds to known issues within the autofill framework.

Resized dialogs aren't considered for autofill

In Android 8.1 (API level 27) and lower, if a view in a dialog is resized after it's already displayed, the view isn't considered for autofill. Such views aren't included in the AssistStructure object that the Android system sends to the autofill service. As a result, the service can't fill out the views.

To work around this issue, replace the token property of the dialog window parameters with the token property of the activity that creates the dialog. After you validate that autofill is enabled, save the window parameters in the onWindowAttributesChanged() method of the class that inherits from Dialog. Then, replace the token property of the saved parameters with the token property of the parent activity in the onAttachedToWindow() method.

The following code snippet shows a class that implements the workaround:

public class MyDialog extends Dialog {
    // Used to store the dialog window parameters.
    private IBinder mToken;

    @Override
    public void onWindowAttributesChanged(WindowManager.LayoutParams params) {
        if (params.token == null && mToken != null) {
            params.token = mToken;
        }

        super.onWindowAttributesChanged(params);
    }

    @Override
    public void onAttachedToWindow() {
        if (isDialogResizedWorkaroundRequired()) {
            mToken = getOwnerActivity().getWindow().getAttributes().token;
        }

        super.onAttachedToWindow();
    }

    private boolean isDialogResizedWorkaroundRequired() {
        if (Build.VERSION.SDK_INT != Build.VERSION_CODES.O
                || Build.VERSION.SDK_INT != Build.VERSION_CODES.O_MR1) {
            return false;
        }
        AutofillManager autofillManager =
            getContext().getSystemService(AutofillManager.class);
        return autofillManager != null && autofillManager.isEnabled();
    }

}

To avoid unnecessary operations, the following code snippet shows how to check if autofill is supported in the device and enabled for the current user, and whether this workaround is required:

public class AutofillHelper {
    public static boolean isDialogResizedWorkaroundRequired(Context context) {
        // After the issue is resolved on Android, you should check if the
        // workaround is still required for the current device.
        return isAutofillAvailable(context);
    }

    public static boolean isAutofillAvailable(Context context) {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
            // The autofill framework is only available on Android 8.0
            // or higher.
            return false;
        }

        AutofillManager afm = context.getSystemService(AutofillManager.class);
        // Return true if autofill is supported by the device and enabled
        // for the current user.
        return afm != null && afm.isEnabled();
    }
}

Test your app with autofill

Most apps work with autofill services without any changes. However, you can optimize your app to ensure it works as best as it can with autofill services. After you optimize your app, you should test it to make sure it works as intended with autofill services.

You should use an emulator or a physical device running Android 8.0 (API level 26) or higher to test your app. For more information about how to create an emulator, see Create and manage virtual devices.

Install an autofill service

Before you can test your app with autofill, you need to install another app that provides autofill services. You could use a third-party app for this purpose, but it's easier to use a sample autofill service so that you don't need to sign up for any third-party services.

You can use the Android autofill framework sample to test your app with autofill services. The sample app provides an autofill service and client Activity classes that you can use to test the workflow before using it with your app. This page references the android-AutofillFramework sample app.

After you have installed the app, you should enable the autofill service in the system settings. You can enable the service by navigating to Settings > System > Languages & input > Advanced > Input assistance > Autofill service.

Analyze data requirements

To test your app with the autofill service, the service needs to have data that it can use to fill out your app. The service also needs to understand what type of data is expected in the views of your app. For example, if your app has a view that expects a username, the service should have a dataset that contains a username and some mechanism to know that the view expects such data.

You should let the service know what type of data is expected in your views by setting the android:autofillHints attribute. Some services use sophisticated heuristics to determine the type of data, but others, such as the sample app, rely on the developer to provide this information. Your app works better with autofill services if you set the android:autofillHints attribute in the views that are relevant for autofill.

Run your test

After you have analyzed the data requirements, you can run your test, which includes saving test data in the autofill service and triggering autofill in your app.

Save data in the service

The following steps show how to save data in the autofill service that is currently active:

  1. Open an app containing a view that expects the type of data you want to use during your test. The android-AutofillFramework sample app provides the UI with views that expect several types of data, such as credit card numbers and usernames.
  2. Tap the view that holds the type of data you need.
  3. Type a value into the view.
  4. Tap the confirmation button, such as Sign in or Submit.

    You usually have to submit the form before the service attempts to save the data.

  5. The system displays a dialog asking for your permission to save the data. The dialog shows the name of the service that is currently active.

    Verify that this is the service that you want to use in your test, and tap Save.

If Android doesn't display the permission dialog, or if the service isn't the one you want to use in your test, then check that the service is currently active in system settings.

Trigger autofill in your app

The following steps show how to trigger autofill in your app:

  1. Open your app and go to the activity that has the views you want to test.
  2. Tap the view that should be filled out.
  3. The system should display the autofill UI, which contains the datasets that can fill the view, as shown in Figure 1.
  4. Tap the dataset that contains the data that you want to use. The view should display the data previously stored in the service.
Autofill UI displaying "dataset-2" as an available dataset
Figure 1. Autofill UI displaying available datasets.

If Android doesn't display the autofill UI, you can try the following troubleshooting options:

  • Check that the views in your app use the correct value in the android:autofillHints attribute. For a list of possible values for the attribute, see the constants prefixed with AUTOFILL_HINT in the View class.
  • Check that the android:importantForAutofill attribute is set to a value other than no on the view that should be filled out, or set to a value other than noExcludeDescendants on the view or one of its parents.