Account Transfer API Example

Learn how to copy google accounts and data from an existing Android device to a new one using Account Transfer API.

You can use the Account Transfer API to let users also copy credentials for custom accounts implemented using AbstractAccountAuthenticator and integrated with AccountManager. The system invokes the Account Transfer API from the Tap & Go setup wizard running on the new device. The system also invokes the Account Transfer API to transfer data from an Android phone to a Pixel using a cable.

You can read more about Account Transfer here.

Let us look at some exmaples.

Example 1: Kotlin AccountTransferApi Example

A sample app demonstrating how to use AccountTransferApi to transfer accounts during the setup of a new device.

• Install the app on the source device.
• Add an account by going to Android Settings. Account username and password can be anything.
• Start Account Transfer flow. Read API Guide for more information on how to trigger the flow.
• After completion, install and open the app to confirm the account has been copied over.

Step 1: Create Project

Start by creating an empty Android Studio project.

Step 2: Dependencies

Go to your app/build.gradle and add the Play Services Auth Base as a dependency:

    // For Account Transfer api, use SDK version 11.2.0 or higher
    implementation 'com.google.android.gms:play-services-auth-base:17.1.2'

Step 3: Add Permissions

Add the following permissions in your app/src/AndroidManifest.xml:

    <uses-permission
        android:name="android.permission.GET_ACCOUNTS"
        android:maxSdkVersion="22" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS"/>

Step 4: Create Authenticator

Go to your res folder and create a folder known as xml and add the following code:

res/xml/authenticator.xml

<?xml version="1.0" encoding="utf-8"?>
<account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
    android:accountType="@string/account_type"
    android:icon="@mipmap/ic_launcher"
    android:smallIcon="@mipmap/ic_launcher"
    android:label="@string/account_label" />

Step 5: Design Layouts

Design two layouts:

(a). login_activity.xml

Add two EditTexts and a Button:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingLeft="17dp"
    android:paddingRight="17dp"
    >

    <EditText android:id="@+id/accountName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:hint="Username"
        android:inputType="textEmailAddress"
        android:padding="10dp"
        />

    <EditText android:id="@+id/accountPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:inputType="textPassword"
        android:hint="Password"
        android:padding="10dp"
        />

    <Button android:id="@+id/submit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Sign in"
        android:padding="10dp"/>

</LinearLayout>

(b). activity_main.xml

Add a refresh button and a TextView to display account text:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

  <TextView
      android:id="@+id/account_text"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>

  <Button
      android:id="@+id/refresh"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="@string/refresh"/>

</LinearLayout>

Step 6: Write Authenticator Code

Create Authenticator.java file and add the following imports:

import android.accounts.AbstractAccountAuthenticator;
import android.accounts.Account;
import android.accounts.AccountAuthenticatorResponse;
import android.accounts.AccountManager;
import android.accounts.NetworkErrorException;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

Extend the AbstractAccountAuthenticator:

public class Authenticator extends AbstractAccountAuthenticator {

Declare a Context object and a TAG:

    private static final String TAG = "Authenticator";
    private final Context mContext;

Let the constructor receive a Context object:

    public Authenticator(Context context) {
        super(context);
        this.mContext = context;
    }

Override the method to add account:

    @Override
    public Bundle addAccount(
            AccountAuthenticatorResponse response,
            String accountType,
            String authTokenType,
            String[] requiredFeatures,
            Bundle options)
            throws NetworkErrorException {
        Log.d(TAG, "addAccount");

        final Intent intent = new Intent(mContext, AuthenticatorActivity.class);
        intent.putExtra(AccountManager.KEY_ACCOUNT_TYPE, accountType);
        intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response);

        final Bundle bundle = new Bundle();
        bundle.putParcelable(AccountManager.KEY_INTENT, intent);
        return bundle;
    }

Override the method to get authentication token, authentication token label, etc. In this case we will return null:

    @Override
    public Bundle getAuthToken(
            AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public String getAuthTokenLabel(String authTokenType) {
        return null;
    }

    @Override
    public Bundle hasFeatures(
            AccountAuthenticatorResponse response, Account account, String[] features)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public Bundle editProperties(AccountAuthenticatorResponse response, String accountType) {
        return null;
    }

    @Override
    public Bundle confirmCredentials(
            AccountAuthenticatorResponse response, Account account, Bundle options)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public Bundle updateCredentials(
            AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)
            throws NetworkErrorException {
        return null;
    }
}

Here is the full code:

Authenticator.java

import android.accounts.AbstractAccountAuthenticator;
import android.accounts.Account;
import android.accounts.AccountAuthenticatorResponse;
import android.accounts.AccountManager;
import android.accounts.NetworkErrorException;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

public class Authenticator extends AbstractAccountAuthenticator {

    private static final String TAG = "Authenticator";
    private final Context mContext;

    public Authenticator(Context context) {
        super(context);
        this.mContext = context;
    }

    @Override
    public Bundle addAccount(
            AccountAuthenticatorResponse response,
            String accountType,
            String authTokenType,
            String[] requiredFeatures,
            Bundle options)
            throws NetworkErrorException {
        Log.d(TAG, "addAccount");

        final Intent intent = new Intent(mContext, AuthenticatorActivity.class);
        intent.putExtra(AccountManager.KEY_ACCOUNT_TYPE, accountType);
        intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response);

        final Bundle bundle = new Bundle();
        bundle.putParcelable(AccountManager.KEY_INTENT, intent);
        return bundle;
    }

    @Override
    public Bundle getAuthToken(
            AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public String getAuthTokenLabel(String authTokenType) {
        return null;
    }

    @Override
    public Bundle hasFeatures(
            AccountAuthenticatorResponse response, Account account, String[] features)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public Bundle editProperties(AccountAuthenticatorResponse response, String accountType) {
        return null;
    }

    @Override
    public Bundle confirmCredentials(
            AccountAuthenticatorResponse response, Account account, Bundle options)
            throws NetworkErrorException {
        return null;
    }

    @Override
    public Bundle updateCredentials(
            AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)
            throws NetworkErrorException {
        return null;
    }
}

Step 7: Create Authenticator Activity

Create AuthenticatorActivity.kt and extend the AccountAuthenticatorActivity class

public class AuthenticatorActivity extends AccountAuthenticatorActivity {

Prepare an AccountManager:

    private AccountManager mAccountManager;

Override the onCreate():

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_activity);

Obtain the accountManager based on the context:

        mAccountManager = AccountManager.get(getBaseContext());

When the submit button is clicked, add an account:

        findViewById(R.id.submit)
                .setOnClickListener(
                        new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                addAccount();
                            }
                        });
    }

Here is the code for adding an account:

    private void addAccount() {
        final String accountName = ((TextView) findViewById(R.id.accountName)).getText().toString();
        final String accountPassword =
                ((TextView) findViewById(R.id.accountPassword)).getText().toString();
        final Intent intent = getIntent();
        final Account account =
                new Account(accountName, intent.getStringExtra(AccountManager.KEY_ACCOUNT_TYPE));

        // There is no check for username/password as this is sample app. Real apps should verify
        // the account credentials before adding it to device.
        mAccountManager.addAccountExplicitly(account, accountPassword, null);
        setResult(RESULT_OK);
        finish();
    }
}

AuthenticatorActivity.java

import android.accounts.Account;
import android.accounts.AccountAuthenticatorActivity;
import android.accounts.AccountManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import com.google.accounttransfer.sample.R;

public class AuthenticatorActivity extends AccountAuthenticatorActivity {

    private AccountManager mAccountManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_activity);
        mAccountManager = AccountManager.get(getBaseContext());

        findViewById(R.id.submit)
                .setOnClickListener(
                        new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                addAccount();
                            }
                        });
    }

    private void addAccount() {
        final String accountName = ((TextView) findViewById(R.id.accountName)).getText().toString();
        final String accountPassword =
                ((TextView) findViewById(R.id.accountPassword)).getText().toString();
        final Intent intent = getIntent();
        final Account account =
                new Account(accountName, intent.getStringExtra(AccountManager.KEY_ACCOUNT_TYPE));

        // There is no check for username/password as this is sample app. Real apps should verify
        // the account credentials before adding it to device.
        mAccountManager.addAccountExplicitly(account, accountPassword, null);
        setResult(RESULT_OK);
        finish();
    }
}

Step 8: Create Authenticator service

Create AuthenticatorService.java add these imports:

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

Extend the android.app.Service:

public class AuthenticatorService extends Service {

Override the onBind() method:

    @Override
    public IBinder onBind(Intent intent) {
        Authenticator authenticator = new Authenticator(this);
        return authenticator.getIBinder();
    }
}

Here is the full code:

AuthenticatorService.java

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

public class AuthenticatorService extends Service {
    @Override
    public IBinder onBind(Intent intent) {
        Authenticator authenticator = new Authenticator(this);
        return authenticator.getIBinder();
    }
}

Step 9: Create an AccountTransfer BroadcastReceiver

Create a AccountTransferBroadcastReceiver.java and extend the android.content.BroadcastReceiver:

public class AccountTransferBroadcastReceiver extends BroadcastReceiver {
    private static final String TAG = "ATBroadcastReceiver";

Override the onReceive():

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d(TAG, "Received intent:" + intent);

Because Long running tasks, like calling Account Transfer API, shouldn't happen here, you start a foreground service to perform long running tasks:

        Intent serviceIntent = AccountTransferService.getIntent(context, intent.getAction());
        if (Build.VERSION.SDK_INT >= 26) {
            context.startForegroundService(serviceIntent);
        } else {
            context.startService(serviceIntent);
        }

Here is the full code:

AccountTransferBroadcastReceiver.java

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.util.Log;

/**
 * Broadcast receiver entry point for listening to Account Transfer Broadcasts.
 */

public class AccountTransferBroadcastReceiver extends BroadcastReceiver {
    private static final String TAG = "ATBroadcastReceiver";

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d(TAG, "Received intent:" + intent);
        // Long running tasks, like calling Account Transfer API, shouldn't happen here. Start a
        // foreground service to perform long running tasks.
        Intent serviceIntent = AccountTransferService.getIntent(context, intent.getAction());
        if (Build.VERSION.SDK_INT >= 26) {
            context.startForegroundService(serviceIntent);
        } else {
            context.startService(serviceIntent);
        }
    }
}

Step 10: Create An Account Tansfer Service

Create the AccountTransferService.java and extend the IntentService:

public class AccountTransferService extends IntentService {

Define the following constants:

    private static final String TAG = "AccountTransferService";
    private static final String ACTION_START_ACCOUNT_EXPORT =
            AccountTransfer.ACTION_START_ACCOUNT_EXPORT;
    private static final String ACCOUNT_TYPE = AccountTransferUtil.ACCOUNT_TYPE;

    private static final String ACCOUNT_TRANSFER_CHANNEL = "TRANSFER ACCOUNTS";
    private static final int NOTIFICATION_ID = 1;

    private static final long TIMEOUT_API = 10;
    private static final TimeUnit TIME_UNIT = TimeUnit.SECONDS;

Create a constructor:

    public AccountTransferService() {
        super("AccountTransferService");
    }

Define a helper method to return an Intent when provided with an action as well as a context:

    public static Intent getIntent(Context context, String action) {
        Intent intent = new Intent();
        intent.setAction(action);
        intent.setClass(context, AccountTransferService.class);
        return intent;
    }

Override our onCreate() and create a Notification as well as starting a foreground service:

    @Override
    public void onCreate() {
        super.onCreate();

        Notification.Builder builder;
        if (Build.VERSION.SDK_INT >= 26) {
            createNotificationChannel();
            builder = new Notification.Builder(this, ACCOUNT_TRANSFER_CHANNEL);
        } else {
            builder = new Notification.Builder(this);
        }
        Notification notification = builder
                .setSmallIcon(R.mipmap.ic_launcher)
                .setTicker(getString(R.string.copying_text))
                .setWhen(System.currentTimeMillis())
                .setContentTitle(getText(R.string.copying_text))
                .setContentText(getString(R.string.copying_text))
                .build();
        startForeground(NOTIFICATION_ID, notification);
    }

Stop the foreground service when the service is being destroyed:

    @Override
    public void onDestroy() {
        stopForeground(true);
        super.onDestroy();
    }

Handle Intent:

    protected void onHandleIntent(Intent intent) {
        String action = intent.getAction();
        if (action == null) {
            Log.e(TAG, "Receiver with action == null");
            return;
        }
        Log.d(TAG, "Receiver with action:" + action);

        switch (action) {

            case AccountTransfer.ACTION_ACCOUNT_IMPORT_DATA_AVAILABLE:
                importAccount();
                return;

            case ACTION_START_ACCOUNT_EXPORT:
            case AccountTransfer.ACTION_ACCOUNT_EXPORT_DATA_AVAILABLE:
                exportAccount();
                return;

            default:
        }
    }

Return null in the onBind():

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

Here is how you import an account:

    private void importAccount() {
        // Handle to client object
        AccountTransferClient client = AccountTransfer.getAccountTransferClient(this);

        // Make RetrieveData api call to get the transferred over data.
        Task<byte[]> transferTask = client.retrieveData(ACCOUNT_TYPE);
        try {
            byte[] transferBytes = Tasks.await(transferTask, TIMEOUT_API, TIME_UNIT);
            AccountTransferUtil.importAccounts(transferBytes, this);
        } catch (ExecutionException | InterruptedException | TimeoutException | JSONException e) {
            Log.e(TAG, "Exception while calling importAccounts()", e);
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_FAILURE);
            return;
        }
        client.notifyCompletion(
                ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_SUCCESS);

    }

Here is how you export an account:

    private void exportAccount() {
        Log.d(TAG, "exportAccount()");
        byte[] transferBytes = AccountTransferUtil.getTransferBytes(this);
        AccountTransferClient client = AccountTransfer.getAccountTransferClient(this);
        if (transferBytes == null) {
            Log.d(TAG, "Nothing to export");
            // Notifying is important.
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_SUCCESS);
            return;
        }

        // Send the data over to the other device.
        Task<Void> exportTask = client.sendData(ACCOUNT_TYPE, transferBytes);
        try {
            Tasks.await(exportTask, TIMEOUT_API, TIME_UNIT);
        } catch (ExecutionException | InterruptedException | TimeoutException e) {
            Log.e(TAG, "Exception while calling exportAccounts()", e);
            // Notifying is important.
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_FAILURE);
            return;
        }
    }

Here is a method to create notification channel:

    private void createNotificationChannel() {
        NotificationManager mNotificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        String id = ACCOUNT_TRANSFER_CHANNEL;
        CharSequence name = "AccountTransfer";
        String description = "Account Transfer";
        int importance = NotificationManager.IMPORTANCE_MIN;
        NotificationChannel mChannel = new NotificationChannel(id, name, importance);
        mChannel.setDescription(description);
        mChannel.enableLights(false);
        mChannel.enableVibration(false);
        mNotificationManager.createNotificationChannel(mChannel);
    }
}

Here is the full code:

AccountTransferService.java

import android.app.IntentService;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.IBinder;
import androidx.annotation.Nullable;
import android.util.Log;
import com.google.android.gms.auth.api.accounttransfer.AccountTransfer;
import com.google.android.gms.auth.api.accounttransfer.AccountTransferClient;
import com.google.android.gms.auth.api.accounttransfer.AuthenticatorTransferCompletionStatus;
import com.google.android.gms.tasks.Task;
import com.google.android.gms.tasks.Tasks;

import org.json.JSONException;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class AccountTransferService extends IntentService {

    private static final String TAG = "AccountTransferService";
    private static final String ACTION_START_ACCOUNT_EXPORT =
            AccountTransfer.ACTION_START_ACCOUNT_EXPORT;
    private static final String ACCOUNT_TYPE = AccountTransferUtil.ACCOUNT_TYPE;

    private static final String ACCOUNT_TRANSFER_CHANNEL = "TRANSFER ACCOUNTS";
    private static final int NOTIFICATION_ID = 1;

    private static final long TIMEOUT_API = 10;
    private static final TimeUnit TIME_UNIT = TimeUnit.SECONDS;

    public AccountTransferService() {
        super("AccountTransferService");
    }

    public static Intent getIntent(Context context, String action) {
        Intent intent = new Intent();
        intent.setAction(action);
        intent.setClass(context, AccountTransferService.class);
        return intent;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        Notification.Builder builder;
        if (Build.VERSION.SDK_INT >= 26) {
            createNotificationChannel();
            builder = new Notification.Builder(this, ACCOUNT_TRANSFER_CHANNEL);
        } else {
            builder = new Notification.Builder(this);
        }
        Notification notification = builder
                .setSmallIcon(R.mipmap.ic_launcher)
                .setTicker(getString(R.string.copying_text))
                .setWhen(System.currentTimeMillis())
                .setContentTitle(getText(R.string.copying_text))
                .setContentText(getString(R.string.copying_text))
                .build();
        startForeground(NOTIFICATION_ID, notification);
    }

    @Override
    public void onDestroy() {
        stopForeground(true);
        super.onDestroy();
    }

    protected void onHandleIntent(Intent intent) {
        String action = intent.getAction();
        if (action == null) {
            Log.e(TAG, "Receiver with action == null");
            return;
        }
        Log.d(TAG, "Receiver with action:" + action);

        switch (action) {

            case AccountTransfer.ACTION_ACCOUNT_IMPORT_DATA_AVAILABLE:
                importAccount();
                return;

            case ACTION_START_ACCOUNT_EXPORT:
            case AccountTransfer.ACTION_ACCOUNT_EXPORT_DATA_AVAILABLE:
                exportAccount();
                return;

            default:
        }
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private void importAccount() {
        // Handle to client object
        AccountTransferClient client = AccountTransfer.getAccountTransferClient(this);

        // Make RetrieveData api call to get the transferred over data.
        Task<byte[]> transferTask = client.retrieveData(ACCOUNT_TYPE);
        try {
            byte[] transferBytes = Tasks.await(transferTask, TIMEOUT_API, TIME_UNIT);
            AccountTransferUtil.importAccounts(transferBytes, this);
        } catch (ExecutionException | InterruptedException | TimeoutException | JSONException e) {
            Log.e(TAG, "Exception while calling importAccounts()", e);
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_FAILURE);
            return;
        }
        client.notifyCompletion(
                ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_SUCCESS);

    }

    private void exportAccount() {
        Log.d(TAG, "exportAccount()");
        byte[] transferBytes = AccountTransferUtil.getTransferBytes(this);
        AccountTransferClient client = AccountTransfer.getAccountTransferClient(this);
        if (transferBytes == null) {
            Log.d(TAG, "Nothing to export");
            // Notifying is important.
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_SUCCESS);
            return;
        }

        // Send the data over to the other device.
        Task<Void> exportTask = client.sendData(ACCOUNT_TYPE, transferBytes);
        try {
            Tasks.await(exportTask, TIMEOUT_API, TIME_UNIT);
        } catch (ExecutionException | InterruptedException | TimeoutException e) {
            Log.e(TAG, "Exception while calling exportAccounts()", e);
            // Notifying is important.
            client.notifyCompletion(
                    ACCOUNT_TYPE, AuthenticatorTransferCompletionStatus.COMPLETED_FAILURE);
            return;
        }
    }

    private void createNotificationChannel() {
        NotificationManager mNotificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        String id = ACCOUNT_TRANSFER_CHANNEL;
        CharSequence name = "AccountTransfer";
        String description = "Account Transfer";
        int importance = NotificationManager.IMPORTANCE_MIN;
        NotificationChannel mChannel = new NotificationChannel(id, name, importance);
        mChannel.setDescription(description);
        mChannel.enableLights(false);
        mChannel.enableVibration(false);
        mNotificationManager.createNotificationChannel(mChannel);
    }
}

Step 11: Create Account Tansfer Utilities

A simple utilities class for Account Transfer functionality:

public class AccountTransferUtil {

    public static final String ACCOUNT_TYPE = "com.accountransfer.account.type";
    public static final String KEY_ACCOUNT_NAME = "account_name";
    public static final String KEY_ACCOUNT_PASSWORD = "account_password";
    public static final String KEY_ACCOUNT_ARRAY = "account_array";

    private static final String TAG = "AccountTransferUtil";

    private AccountTransferUtil() {}

    static void importAccounts(byte[] transferBytes, Context context) throws JSONException {
        if (transferBytes != null) {
            String jsonString = new String(transferBytes, Charset.forName("UTF-8"));
            JSONObject object = new JSONObject(jsonString);
            JSONArray jsonArray = object.getJSONArray(KEY_ACCOUNT_ARRAY);
            for (int i = 0, size = jsonArray.length(); i < size; i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String password = jsonObject.getString(KEY_ACCOUNT_PASSWORD);
                String name = jsonObject.getString(KEY_ACCOUNT_NAME);
                Account newAccount = new Account(
                        name + " COPY time:" + System.currentTimeMillis(), ACCOUNT_TYPE);
                boolean result = AccountManager.get(context)
                        .addAccountExplicitly(newAccount, password, null);
                // Don't log PII in actual app.
                Log.d(TAG, "Added account:" + newAccount + " with password:" + password
                        + " with result:" + result);
                Log.d(TAG, "Don't log PII in actual app");

            }
        }
    }

    static byte[] getTransferBytes(Context context) {
        AccountManager am = AccountManager.get(context);
        Account[] accounts = am.getAccountsByType(ACCOUNT_TYPE);
        String msg = "Length of accounts of type com.mfm are " + accounts.length;
        Log.v(TAG, msg);
        if (accounts.length != 0) {
            JSONArray jsonArray = new JSONArray();
            for (Account account : accounts) {
                JSONObject jsonObject = new JSONObject();
                try {
                    jsonObject.put(KEY_ACCOUNT_NAME, account.name);
                    String password  = am.getPassword(account);
                    jsonObject.put(KEY_ACCOUNT_PASSWORD, password);
                } catch (JSONException e) {
                    Log.e(TAG, "Error while creating bytes for transfer", e);
                    return null;
                }
                jsonArray.put(jsonObject);
            }
            JSONObject object = new JSONObject();
            try {
                object.put(KEY_ACCOUNT_ARRAY, jsonArray);
            } catch (JSONException e) {
                Log.e(TAG, "Error", e);
                return null;
            }
            return object.toString().getBytes(Charset.forName("UTF-8"));
        }
        return null;
    }
}

Step 12: MainActivity

Here is the code for the MainActivity.java

import android.accounts.Account;
import android.accounts.AccountManager;
import android.content.SharedPreferences;
import android.graphics.Color;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import com.google.android.gms.auth.api.accounttransfer.AccountTransfer;
import com.google.android.gms.auth.api.accounttransfer.AccountTransferClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;

import org.json.JSONException;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    private static final String SHARED_PREF = "accountTransfer";
    private static final String KEY_FIRST_TIME = "first_time";
    private static final String ACCOUNT_TYPE = AccountTransferUtil.ACCOUNT_TYPE;

    private static Boolean firstTime = null;
    SharedPreferences sharedPreferences;
    private TextView mAccountTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAccountTextView = (TextView) findViewById(R.id.account_text);
        findViewById(R.id.refresh).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                populateAccountTextView();
            }
        });
        // In production app, call this in a background thread, showing progress screen meanwhile.
        fetchData();
    }

    @Override
    protected void onResume() {
        super.onResume();
        populateAccountTextView();
    }

    private void populateAccountTextView() {
        AccountManager am = AccountManager.get(this);
        Account[] accounts = am.getAccountsByType(ACCOUNT_TYPE);
        String accountString = "Accounts of type " + ACCOUNT_TYPE + " are : \n";
        if (accounts.length != 0) {
            for (Account account : accounts) {
                accountString += "Account:" +  account.name + "\n";
            }
        } else {
            accountString = "No Accounts of type " + ACCOUNT_TYPE +
                    " found. Please add accounts before exporting.";
            mAccountTextView.setTextColor(Color.RED);
        }
        mAccountTextView.setText(accountString);
    }

    private void fetchData() {
        // The logic can be modified according to your need.
        sharedPreferences = getSharedPreferences(SHARED_PREF, MODE_PRIVATE);
        firstTime = sharedPreferences.getBoolean(KEY_FIRST_TIME, true);
        if (firstTime) {
            Log.v(TAG, "Fetching account info from API");
            AccountTransferClient client = AccountTransfer.getAccountTransferClient(this);
            final Task<byte[]> transferBytes = client.retrieveData(ACCOUNT_TYPE);
            transferBytes.addOnCompleteListener(this, new OnCompleteListener<byte[]>() {
                @Override
                public void onComplete(@NonNull Task<byte[]> task) {
                    if (task.isSuccessful()) {
                        Log.d(TAG, "Success retrieving data. Importing it.");
                        try {
                            AccountTransferUtil.importAccounts(task.getResult(), MainActivity.this);
                        } catch (JSONException e) {
                            Log.e(TAG, "Encountered failure while retrieving data", e);
                            return;
                        }
                        populateAccountTextView();
                    } else {
                        // No need to notify API about failure, as it's running outside setup of
                        // device.
                        Log.e(TAG, "Encountered failure while retrieving data", task.getException());
                    }
                    // Don't try the next time
                    sharedPreferences.edit().putBoolean(KEY_FIRST_TIME, false).apply();
                }
            });
        }
    }
}

Run

Copy the code or download it in the link below, build and run.

Reference

Here are the reference links:

Number	Link
1.	Download Example
2.	Follow code author
3.	Code: Apache 2.0 License