AndroidアプリでGoogleアカウント名を取得したい

前提・発生している問題・エラーメッセージ

ログイン済みのGoogleアカウントからアカウント名(~@gmail.com)を取得したいです。
ですがnullが返され、アカウント名が取得できません。

該当のソースコード

サンプルコードを元にしていますが、startActivityResult,ActivityResultが非推奨となる可能性があることを見込んで、ActivityResultLauncherで記述しています。

Java
1//サインイン済みのアカウント選択
2        Intent getgsc = credential.newChooseAccountIntent();
3
4//アカウントが選択されたらアカウント名を取得、キャンセルされたらアプリを終了
5	ActivityResultLauncher<Intent> chooseaccount = registerForActivityResult(
6          new ActivityResultContracts.StartActivityForResult(),
7          new ActivityResultCallback<ActivityResult>(){
8        @Override
9      	public void onActivityResult(ActivityResult result) {
10		    if (result.getResultCode() == Activity.RESULT_OK) {
11                	String accountName = getgsc.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
12                        Toast tst_accountName = Toast.makeText(getApplicationContext(), accountName, Toast.LENGTH_LONG);
13                        tst_accountName.show();
14                        if (accountName != null) {
15                            SharedPreferences settings =
16                                    getPreferences(Context.MODE_PRIVATE);
17                            SharedPreferences.Editor editor = settings.edit();
18                            editor.putString(PREF_ACCOUNT_NAME, accountName);
19                            editor.apply();
20                            credential.setSelectedAccountName(accountName);
21                        }
22		    } else if (result.getResultCode() == Activity.RESULT_CANCELED) {
23		        finishAndRemoveTask();
24		    } else {
25		    }
26    	        }
27        });
28
29    …
30
31    chooseaccount.launch(getgsc);
32

###詳細コード

MainActivity
1package com.example.test;
2
3import android.Manifest;
4import androidx.appcompat.app.AppCompatActivity;
5
6import android.app.Activity;
7import android.os.Bundle;
8import android.app.Dialog;
9import android.content.Context;
10import com.google.android.gms.auth.api.signin.GoogleSignInClient;
11import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
12import com.google.android.gms.auth.api.signin.GoogleSignIn;
13import com.google.android.gms.common.api.Scope;
14import android.content.Intent;
15import androidx.activity.result.ActivityResultCaller;
16import androidx.activity.result.ActivityResultLauncher;
17import androidx.activity.result.ActivityResultCallback;
18import androidx.activity.result.contract.ActivityResultContracts;
19import androidx.activity.result.ActivityResult;
20import androidx.biometric.BiometricManager.Authenticators;
21import android.provider.Settings;
22
23import com.google.api.client.util.ExponentialBackOff;
24import com.google.api.services.sheets.v4.Sheets;
25import com.google.api.services.sheets.v4.model.*;
26import com.google.api.services.sheets.v4.SheetsScopes;
27import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
28import android.accounts.AccountManager;
29import android.content.SharedPreferences;
30
31import com.google.android.gms.common.AccountPicker;
32import com.google.android.gms.common.AccountPicker.AccountChooserOptions;
33
34//Debug
35import android.widget.Button;
36import android.view.View;
37import android.widget.Toast;
38import android.util.Log;
39import java.util.List;
40import java.util.Arrays;
41import java.io.IOException;
42import java.util.ArrayList;
43import pub.devrel.easypermissions.AfterPermissionGranted;
44import pub.devrel.easypermissions.EasyPermissions;
45
46public class MainActivity extends AppCompatActivity
47    implements Authenticators{
48    public final int REQUEST_DRIVE = 1;
49    public final int REQUEST_SHEETS = 10;
50    public final int REQUEST_CODE= 100;
51    public final Scope SCOPE_DRIVE = new Scope("https://www.googleapis.com/auth/drive");
52    public final Scope SCOPE_SHEETS = new Scope("https://www.googleapis.com/auth/spreadsheets");
53    public final String[] SCOPES_ARRAYS = {SheetsScopes.DRIVE, SheetsScopes.SPREADSHEETS};
54    public final List<String> SCOPES = Arrays.asList(SCOPES_ARRAYS);
55    public static final String PREF_ACCOUNT_NAME = "accountName";
56    public static final String accountName = "null";
57    public GoogleAccountCredential credential;
58
59    protected void onCreate(Bundle savedInstanceState) {
60        super.onCreate(savedInstanceState);
61        setContentView(R.layout.activity_main);
62
63	credential = GoogleAccountCredential.usingOAuth2(getApplicationContext(), SCOPES)
64	    .setBackOff(new ExponentialBackOff());
65
66        Intent getgsc = credential.newChooseAccountIntent();
67
68	ActivityResultLauncher<Intent> chooseaccount = registerForActivityResult(
69          new ActivityResultContracts.StartActivityForResult(),
70          new ActivityResultCallback<ActivityResult>(){
71        @Override
72      	public void onActivityResult(ActivityResult result) {
73		    if (result.getResultCode() == Activity.RESULT_OK && getgsc.getExtras() != null) {
74                	String accountName = getgsc.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
75                        Toast tst_accountName = Toast.makeText(getApplicationContext(), accountName, Toast.LENGTH_LONG);
76                        tst_accountName.show();
77                        if (accountName != null) {
78                            SharedPreferences settings =
79                                    getPreferences(Context.MODE_PRIVATE);
80                            SharedPreferences.Editor editor = settings.edit();
81                            editor.putString(PREF_ACCOUNT_NAME, accountName);
82                            editor.apply();
83                            credential.setSelectedAccountName(accountName);
84                        }
85		    } else if (result.getResultCode() == Activity.RESULT_CANCELED) {
86		        finishAndRemoveTask();
87		    } else {
88		    }
89    	        }
90        });
91
92	Button btn = findViewById(R.id.switch1);
93	btn.setOnClickListener(new View.OnClickListener(){
94	    public void onClick(View view){
95                chooseaccount.launch(getgsc);
96	    }
97	});
98    }
99}

layout
1<?xml version="1.0" encoding="utf-8"?>
2<LinearLayout
3    xmlns:android="http://schemas.android.com/apk/res/android"
4    xmlns:tools="http://schemas.android.com/tools"
5    xmlns:app="http://schemas.android.com/apk/res-auto"
6    android:layout_width="match_parent"
7    android:layout_height="match_parent"
8    android:orientation="vertical"
9    tools:context=".MainActivity">
10
11    <LinearLayout
12        android:orientation="horizontal"
13        android:layout_width="match_parent"
14        android:layout_height="wrap_content">
15        <TextView
16            android:text="スイッチ"
17            android:layout_width="0dp"
18            android:layout_height="wrap_content"
19            android:layout_weight="3"
20            android:textStyle="bold"
21            android:textSize="20sp"/>
22        <Button
23            android:id="@+id/switch1"
24            android:layout_width="0dp"
25            android:layout_height="wrap_content"
26            android:layout_weight="1.5"
27            android:text="スイッチ"/>
28    </LinearLayout>
29
30</LinearLayout>