Abstract base class for creating AccountAuthenticators. In order to be an authenticator one must extend this class, provider implementations for the abstract methods and write a service that returns the result of AbstractAccountAuthenticator.IBinder in the service's Android.App.Service.OnBind(Android.Content.Intent) when invoked with an intent with action AccountManager.ActionAuthenticatorIntent. This service must specify the following intent filter and metadata tags in its AndroidManifest.xml file

   <intent-filter>
     <action android:name="android.accounts.AccountAuthenticator" />
   </intent-filter>
   <meta-data android:name="android.accounts.AccountAuthenticator"
             android:resource="@xml/authenticator" />
 

 <account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
    android:accountType="typeOfAuthenticator"
    android:icon="@drawable/icon"
    android:smallIcon="@drawable/miniIcon"
    android:label="@string/label"
    android:accountPreferences="@xml/account_preferences"
 />
 

The preferences attribute points to a PreferenceScreen xml hierarchy that contains a list of PreferenceScreens that can be invoked to manage the authenticator. An example is:

 <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <PreferenceCategory android:title="@string/title_fmt" />
    <PreferenceScreen
         android:key="key1"
         android:title="@string/key1_action"
         android:summary="@string/key1_summary">
         <intent
             android:action="key1.ACTION"
             android:targetPackage="key1.package"
             android:targetClass="key1.class" />
     </PreferenceScreen>
 </PreferenceScreen>
 

The standard pattern for implementing any of the abstract methods is the following:

• If the supplied arguments are enough for the authenticator to fully satisfy the request then it will do so and return a Android.OS.Bundle that contains the results.
• If the authenticator needs information from the user to satisfy the request then it will create an Android.Content.Intent to an activity that will prompt the user for the information and then carry out the request. This intent must be returned in a Bundle as key AccountManager.KeyIntent. The activity needs to return the final result when it is complete so the Intent should contain the Android.Accounts.AccountAuthenticatorResponse as AccountManager.KeyAccountManagerResponse. The activity must then call AccountAuthenticatorResponse.OnResult(Android.OS.Bundle) or AccountAuthenticatorResponse.OnError(ErrorCode, System.String) when it is complete.
• If the authenticator cannot synchronously process the request and return a result then it may choose to return null and then use the AccountManagerResponse to send the result when it has completed the request.

The following descriptions of each of the abstract authenticator methods will not describe the possible asynchronous nature of the request handling and will instead just describe the input parameters and the expected result.

When writing an activity to satisfy these requests one must pass in the AccountManagerResponse and return the result via that response when the activity finishes (or whenever else the activity author deems it is the correct time to respond). The Android.Accounts.AccountAuthenticatorActivity handles this, so one may wish to extend that when writing activities to handle these requests.

[Android Documentation]